Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 02/15/07

AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1140 AM EST TUE FEB 13 2007 .AVIATION DISCUSSION (18Z TAFS)... AN AREA OF LOW PRESSURE WILL MOVE FROM ARKANSAS INTO TENNESSEE AND THEN THROUGH SOUTHEASTERN KENTUCKY LATER TONIGHT. AS THE LOW NEARS THE REGION THE PRESSURE GRADIENT WILL TIGHTEN PRODUCING GUSTY WINDS LATE THIS AFTERNOON INTO THE OVERNIGHT PERIOD AT ALL TAF SITES. PEAK WINDS WILL ARRIVE AROUND MIDNIGHT..WITH NORTHERLY WIND GUSTS UP TO 25 MPH. WIDESPREAD PRECIP AND LIFR CONDITIONS WILL CONTINUE THROUGH 00Z FOR LEX AND SDF...AND 22Z FOR BWG. SOME MIX OF FROZEN PRECIP WILL BE POSSIBLE THIS EVENING WITH SOME SNOW LATE TONIGHT. MODERATE RAIN MAY LOWER VSBY TO AROUND OR LESS THAN 2 SM AT TIMES THROUGH THE EVENING HOURS. JSD && .LATE MORNING UPDATE... MADE VERY FEW CHANGES TO ONGOING GRIDS. HAVE LOWERED AFTERNOON HIGHS ACROSS OUR SOUTHERN COUNTIES A FEW DEGREES. HAVE ALSO SLIGHTLY DELAYED THE CHANGEOVER OF RAIN TO FROZEN PRECIP ALONG AND SOUTH OF THE OHIO RIVER TO EARLY EVENING. SOME QUESTION REMAINS AS TO WHETHER OUR SOUTHERN INDIANA WILL MEET WINTER WEATHER ADVISORY CONDITIONS THIS EVENING BEFORE PRECIP ENDS AFTER MIDNIGHT. ALONG AND SOUTH OF THE OHIO RIVER...ANY SLEET OR SNOW ACCUMULATIONS STILL EXPECTED TO BE ONE HALF INCH OR LESS. JSD && .PREV DISCUSSION... /ISSUED 323 AM EST TUE FEB 13 2007/ SHORT TERM (TODAY AND TONIGHT)... SOUTH CENTRAL INDIANA AND CENTRAL KENTUCKY WILL MISS OUT ON THE BIGGEST WINTER STORM SINCE DEC 2004 HERE IN THE OHIO VALLEY. VERY LITTLE ADJUSTMENT NEEDED TO THE CURRENT FORECAST PACKAGE...SHORT RANGE MODELS HAVE NOT ALTERED THE TRACK OF THE LOW MUCH SINCE THE 12Z RUNS FROM YESTERDAY. SREF LOOKS LIKE A VERY REASONABLE SOLUTION AND HAS INITIALIZED THE UPPER LEVEL LOW BETTER THAN THE 00Z NAM OR GFS. ONLY MINOR TWEAKS MADE TO EXISTING GRIDS...MAINLY TO TIMING OF COLDER AIR WORKING INTO THE REGION...AND THE P-TYPE CHANGEOVER ASSOCIATED. CURRENT SITUATION LOOKS AS FOLLOWS...STATIONARY BOUNDARY SITS FROM THE RED RIVER VALLEY TO NEAR NASHVILLE AND ON EASTWARDS INTO THE CAROLINAS. SURFACE LOW JUST NORTHEAST OF DALLAS...TRACKING EAST ALONG THE BOUNDARY AS WELL AS THE UPPER LEVEL LOW WHICH IS CENTERED OVER EASTERN OKLAHOMA. WAA ALOFT HAS WARMED H850 TEMPS TO NEAR 38 DEGREES WITH THE FREEZING LINE ABOVE 8000 FEET PER THE LATEST ACARS SOUNDINGS. SURFACE TEMPS ARE HOLDING STEADY IN THE 32 TO 36 RANGE ACROSS THE NORTHERN HALF OF THE FORECAST AREA...WARMER NEAR 40 ACROSS THE SOUTH THIS MORNING. REGIONAL RADAR SHOWS LARGE LINEAR AREA OF RAIN STRETCHING FROM THE LOWER MS VALLEY INTO THE MID OH VALLEY...SLOWLY DRIFTING EASTWARD. BY EARLY THIS AFTERNOON THE UPPER LEVEL LOW WILL HAVE MADE ITS WAY INTO THE MS VALLEY...WITH THE SURFACE LOW NEARING THE NASHVILLE AREA. AS THE LOW APPROACHES THE PRESSURE GRADIENT WILL TIGHTEN AND WINDS WILL INCREASE THROUGH THE AFTERNOON INTO THE EVENING. THE LARGE AREA OF RAIN WILL ENGULF THE FORECAST AREA OVER THE COURSE OF THE MORNING...REACHING THE BLUEGRASS REGION AND THE LAKE CUMBERLAND AND DALE HOLLOW LAKES AREAS BY 15 OR 16Z. RAIN SHOULD CONTINUE THROUGH THE AFTERNOON AS THE SURFACE LOW MOVES TOWARDS SOUTHEAST KY. RAINFALL AMOUNTS MAY REACH 1 INCH PLUS THROUGH THE END OF THE AFTERNOON WITH PWATS MORE THAN 2 STD DEVIATIONS ABOVE NORMAL AND THE STRONG DEFORMATION ACROSS THE REGION AND DECENT SPEED CONVERGENCE SEEN AT BOTH 850 AND 700MB...ALL ENHANCING LIFT. COLDER AIR WILL START TO BE PULLED INTO THE REGION FROM THE NORTHWEST TO SOUTHEAST AS THE SURFACE LOW EXITS THE AREA...THE FAR NORTHERN TIER OF THE FORECAST AREA FROM JASPER TO MADISON MAY SEE A TRANSITION TO FREEZING RAIN OR SLEET LATE THIS AFTERNOON AROUND 5PM...WITH THE REST OF THE REGION IN THE EVENING. PRECIP WILL SLOWLY END FROM SOUTHWEST TO NORTHEAST DURING THE LATE NIGHT HOURS...WRAPPING UP BY EARLY WEDNESDAY MORNING. A SMALL ACCUMULATION OF ICE (ONE TENTH) OR SNOW (.5 TO 1 IN) WILL BE POSSIBLE...MORE LIKELY NORTH OF A LINE FROM TELL CITY INDIANA TO RICHMOND KENTUCKY. WILL ISSUE SPS FOR THESE AREAS HIGHLIGHTING THE POSSIBILITY OF SOME SLICK SPOTS DUE TO THE ICE OR SNOW. SCHOTT LONG TERM (WEDNESDAY THROUGH MONDAY).... A MOSTLY DRY AND COLD PERIOD SHAPING UP THROUGH THE WEEKEND. OVERALL FCST TRENDS FOR THE LONG TERM STILL LOOK GOOD. THE WESTERN U.S. RIDGE REBUILDS. OUR REGION ONCE AGAIN COMES UNDER THE INFLUENCE OF A NWLY FLOW PATTERN WHICH WILL KEEP A STEADY SUPPLY OF COLD THAN NORMAL ARCTIC AIR ACROSS THE REGION THOUGH THE EXTENDED PERIOD. HIGH TEMPERATURES FOR THIS TIME OF THE YEAR RANGE FROM THE MIDDLE TO UPPER 40S VERSUS OUR FCST HIGHS IN 20S TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY. EVEN THOUGH WE WARM UP SOME LATE IN THE WEEK AND DURING THE WEEKEND...THE FCST HIGHS WILL STILL BE SOME 10 TO 15 DEGS BELOW NORMAL. THE OVERALL DRY TREND IS BRIEFLY INTERRUPTED ON FRIDAY NIGHT INTO SATURDAY. LATEST LONG RANGE MODEL FCSTS CONTINUE TO INDICATE A CLIPPER LIKE SYSTEM DROPPING SOUTHEAST INTO THE REGION LATE FRIDAY NIGHT INTO SATURDAY THAT COULD CAUSE SOME LIGHT SNOW OR A WINTRY MIX DURING THAT TIME. THE PRECIPITATION TOTALS SHOULD BE LIGHT. OUR CURRENT FCST TRENDS INDICATE THIS WELL...SO NO ADJUSTMENTS NEEDED FOR THIS FCST. --21 .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
611 AM EST TUE FEB 13 2007 .AVIATION DISCUSSION (12Z TAFS)... AREA OF LOW PRESSURE WILL MOVE FROM ARKANSAS INTO TENNESSEE AND THEN THROUGH SOUTHEASTERN KENTUCKY TODAY. AS THE LOW NEAR THE REGION THE PRESSURE GRADIENT WILL TIGHTEN PRODUCING GUSTY WINDS THIS AFTERNOON INTO THE OVERNIGHT PERIOD AT ALL TAF SITES. PRECIP WILL OVERSPREAD THE REGION DURING THE MORNING HOURS...AND CONTINUE INTO THE EVENING...SOME MIX OF FROZEN PRECIP WILL BE POSSIBLE THIS EVENING WITH SOME SNOW LATE TONIGHT. LIFR CONDITIONS WILL CONTINUE AT LEX AND SDF THROUGH MUCH IF NOT ALL OF THE PERIOD...AND SHOULD DEVELOP AT BWG BY LATE MORNING...AS CEILING WILL DROP BELOW 1K FEET. ALSO MODERATE RAIN MAY LOWER VSBY TO AROUND OR LESS THAN 2 SM AT TIMES. SCHOTT && .PREV DISCUSSION... /ISSUED 323 AM EST TUE FEB 13 2007/ SHORT TERM (TODAY AND TONIGHT)... SOUTH CENTRAL INDIANA AND CENTRAL KENTUCKY WILL MISS OUT ON THE BIGGEST WINTER STORM SINCE DEC 2004 HERE IN THE OHIO VALLEY. VERY LITTLE ADJUSTMENT NEEDED TO THE CURRENT FORECAST PACKAGE...SHORT RANGE MODELS HAVE NOT ALTERED THE TRACK OF THE LOW MUCH SINCE THE 12Z RUNS FROM YESTERDAY. SREF LOOKS LIKE A VERY REASONABLE SOLUTION AND HAS INITIALIZED THE UPPER LEVEL LOW BETTER THAN THE 00Z NAM OR GFS. ONLY MINOR TWEAKS MADE TO EXISTING GRIDS...MAINLY TO TIMING OF COLDER AIR WORKING INTO THE REGION...AND THE P-TYPE CHANGEOVER ASSOCIATED. CURRENT SITUATION LOOKS AS FOLLOWS...STATIONARY BOUNDARY SITS FROM THE RED RIVER VALLEY TO NEAR NASHVILLE AND ON EASTWARDS INTO THE CAROLINAS. SURFACE LOW JUST NORTHEAST OF DALLAS...TRACKING EAST ALONG THE BOUNDARY AS WELL AS THE UPPER LEVEL LOW WHICH IS CENTERED OVER EASTERN OKLAHOMA. WAA ALOFT HAS WARMED H850 TEMPS TO NEAR 38 DEGREES WITH THE FREEZING LINE ABOVE 8000 FEET PER THE LATEST ACARS SOUNDINGS. SURFACE TEMPS ARE HOLDING STEADY IN THE 32 TO 36 RANGE ACROSS THE NORTHERN HALF OF THE FORECAST AREA...WARMER NEAR 40 ACROSS THE SOUTH THIS MORNING. REGIONAL RADAR SHOWS LARGE LINEAR AREA OF RAIN STRETCHING FROM THE LOWER MS VALLEY INTO THE MID OH VALLEY...SLOWLY DRIFTING EASTWARD. BY EARLY THIS AFTERNOON THE UPPER LEVEL LOW WILL HAVE MADE ITS WAY INTO THE MS VALLEY...WITH THE SURFACE LOW NEARING THE NASHVILLE AREA. AS THE LOW APPROACHES THE PRESSURE GRADIENT WILL TIGHTEN AND WINDS WILL INCREASE THROUGH THE AFTERNOON INTO THE EVENING. THE LARGE AREA OF RAIN WILL ENGULF THE FORECAST AREA OVER THE COURSE OF THE MORNING...REACHING THE BLUEGRASS REGION AND THE LAKE CUMBERLAND AND DALE HOLLOW LAKES AREAS BY 15 OR 16Z. RAIN SHOULD CONTINUE THROUGH THE AFTERNOON AS THE SURFACE LOW MOVES TOWARDS SOUTHEAST KY. RAINFALL AMOUNTS MAY REACH 1 INCH PLUS THROUGH THE END OF THE AFTERNOON WITH PWATS MORE THAN 2 STD DEVIATIONS ABOVE NORMAL AND THE STRONG DEFORMATION ACROSS THE REGION AND DECENT SPEED CONVERGENCE SEEN AT BOTH 850 AND 700MB...ALL ENHANCING LIFT. COLDER AIR WILL START TO BE PULLED INTO THE REGION FROM THE NORTHWEST TO SOUTHEAST AS THE SURFACE LOW EXITS THE AREA...THE FAR NORTHERN TIER OF THE FORECAST AREA FROM JASPER TO MADISON MAY SEE A TRANSITION TO FREEZING RAIN OR SLEET LATE THIS AFTERNOON AROUND 5PM...WITH THE REST OF THE REGION IN THE EVENING. PRECIP WILL SLOWLY END FROM SOUTHWEST TO NORTHEAST DURING THE LATE NIGHT HOURS...WRAPPING UP BY EARLY WEDNESDAY MORNING. A SMALL ACCUMULATION OF ICE (ONE TENTH) OR SNOW (.5 TO 1 IN) WILL BE POSSIBLE...MORE LIKELY NORTH OF A LINE FROM TELL CITY INDIANA TO RICHMOND KENTUCKY. WILL ISSUE SPS FOR THESE AREAS HIGHLIGHTING THE POSSIBILITY OF SOME SLICK SPOTS DUE TO THE ICE OR SNOW. SCHOTT LONG TERM (WEDNESDAY THROUGH MONDAY).... A MOSTLY DRY AND COLD PERIOD SHAPING UP THROUGH THE WEEKEND. OVERALL FCST TRENDS FOR THE LONG TERM STILL LOOK GOOD. THE WESTERN U.S. RIDGE REBUILDS. OUR REGION ONCE AGAIN COMES UNDER THE INFLUENCE OF A NWLY FLOW PATTERN WHICH WILL KEEP A STEADY SUPPLY OF COLD THAN NORMAL ARCTIC AIR ACROSS THE REGION THOUGH THE EXTENDED PERIOD. HIGH TEMPERATURES FOR THIS TIME OF THE YEAR RANGE FROM THE MIDDLE TO UPPER 40S VERSUS OUR FCST HIGHS IN 20S TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY. EVEN THOUGH WE WARM UP SOME LATE IN THE WEEK AND DURING THE WEEKEND...THE FCST HIGHS WILL STILL BE SOME 10 TO 15 DEGS BELOW NORMAL. THE OVERALL DRY TREND IS BRIEFLY INTERRUPTED ON FRIDAY NIGHT INTO SATURDAY. LATEST LONG RANGE MODEL FCSTS CONTINUE TO INDICATE A CLIPPER LIKE SYSTEM DROPPING SOUTHEAST INTO THE REGION LATE FRIDAY NIGHT INTO SATURDAY THAT COULD CAUSE SOME LIGHT SNOW OR A WINTRY MIX DURING THAT TIME. THE PRECIPITATION TOTALS SHOULD BE LIGHT. OUR CURRENT FCST TRENDS INDICATE THIS WELL...SO NO ADJUSTMENTS NEEDED FOR THIS FCST. --21 .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
323 AM EST TUE FEB 13 2007 .SHORT TERM (TODAY AND TONIGHT)... SOUTH CENTRAL INDIANA AND CENTRAL KENTUCKY WILL MISS OUT ON THE BIGGEST WINTER STORM SINCE DEC 2004 HERE IN THE OHIO VALLEY. VERY LITTLE ADJUSTMENT NEEDED TO THE CURRENT FORECAST PACKAGE...SHORT RANGE MODELS HAVE NOT ALTERED THE TRACK OF THE LOW MUCH SINCE THE 12Z RUNS FROM YESTERDAY. SREF LOOKS LIKE A VERY REASONABLE SOLUTION AND HAS INITIALIZED THE UPPER LEVEL LOW BETTER THAN THE 00Z NAM OR GFS. ONLY MINOR TWEAKS MADE TO EXISTING GRIDS...MAINLY TO TIMING OF COLDER AIR WORKING INTO THE REGION...AND THE P-TYPE CHANGEOVER ASSOCIATED. CURRENT SITUATION LOOKS AS FOLLOWS...STATIONARY BOUNDARY SITS FROM THE RED RIVER VALLEY TO NEAR NASHVILLE AND ON EASTWARDS INTO THE CAROLINAS. SURFACE LOW JUST NORTHEAST OF DALLAS...TRACKING EAST ALONG THE BOUNDARY AS WELL AS THE UPPER LEVEL LOW WHICH IS CENTERED OVER EASTERN OKLAHOMA. WAA ALOFT HAS WARMED H850 TEMPS TO NEAR 38 DEGREES WITH THE FREEZING LINE ABOVE 8000 FEET PER THE LATEST ACARS SOUNDINGS. SURFACE TEMPS ARE HOLDING STEADY IN THE 32 TO 36 RANGE ACROSS THE NORTHERN HALF OF THE FORECAST AREA...WARMER NEAR 40 ACROSS THE SOUTH THIS MORNING. REGIONAL RADAR SHOWS LARGE LINEAR AREA OF RAIN STRETCHING FROM THE LOWER MS VALLEY INTO THE MID OH VALLEY...SLOWLY DRIFTING EASTWARD. BY EARLY THIS AFTERNOON THE UPPER LEVEL LOW WILL HAVE MADE ITS WAY INTO THE MS VALLEY...WITH THE SURFACE LOW NEARING THE NASHVILLE AREA. AS THE LOW APPROACHES THE PRESSURE GRADIENT WILL TIGHTEN AND WINDS WILL INCREASE THROUGH THE AFTERNOON INTO THE EVENING. THE LARGE AREA OF RAIN WILL ENGULF THE FORECAST AREA OVER THE COURSE OF THE MORNING...REACHING THE BLUEGRASS REGION AND THE LAKE CUMBERLAND AND DALE HOLLOW LAKES AREAS BY 15 OR 16Z. RAIN SHOULD CONTINUE THROUGH THE AFTERNOON AS THE SURFACE LOW MOVES TOWARDS SOUTHEAST KY. RAINFALL AMOUNTS MAY REACH 1 INCH PLUS THROUGH THE END OF THE AFTERNOON WITH PWATS MORE THAN 2 STD DEVIATIONS ABOVE NORMAL AND THE STRONG DEFORMATION ACROSS THE REGION AND DECENT SPEED CONVERGENCE SEEN AT BOTH 850 AND 700MB...ALL ENHANCING LIFT. COLDER AIR WILL START TO BE PULLED INTO THE REGION FROM THE NORTHWEST TO SOUTHEAST AS THE SURFACE LOW EXITS THE AREA...THE FAR NORTHERN TIER OF THE FORECAST AREA FROM JASPER TO MADISON MAY SEE A TRANSITION TO FREEZING RAIN OR SLEET LATE THIS AFTERNOON AROUND 5PM...WITH THE REST OF THE REGION IN THE EVENING. PRECIP WILL SLOWLY END FROM SOUTHWEST TO NORTHEAST DURING THE LATE NIGHT HOURS...WRAPPING UP BY EARLY WEDNESDAY MORNING. A SMALL ACCUMULATION OF ICE (ONE TENTH) OR SNOW (.5 TO 1 IN) WILL BE POSSIBLE...MORE LIKELY NORTH OF A LINE FROM TELL CITY INDIANA TO RICHMOND KENTUCKY. WILL ISSUE SPS FOR THESE AREAS HIGHLIGHTING THE POSSIBILITY OF SOME SLICK SPOTS DUE TO THE ICE OR SNOW. SCHOTT .LONG TERM (WEDNESDAY THROUGH MONDAY).... A MOSTLY DRY AND COLD PERIOD SHAPING UP THROUGH THE WEEKEND. OVERALL FCST TRENDS FOR THE LONG TERM STILL LOOK GOOD. THE WESTERN U.S. RIDGE REBUILDS. OUR REGION ONCE AGAIN COMES UNDER THE INFLUENCE OF A NWLY FLOW PATTERN WHICH WILL KEEP A STEADY SUPPLY OF COLD THAN NORMAL ARCTIC AIR ACROSS THE REGION THOUGH THE EXTENDED PERIOD. HIGH TEMPERATURES FOR THIS TIME OF THE YEAR RANGE FROM THE MIDDLE TO UPPER 40S VERSUS OUR FCST HIGHS IN 20S TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY. EVEN THOUGH WE WARM UP SOME LATE IN THE WEEK AND DURING THE WEEKEND...THE FCST HIGHS WILL STILL BE SOME 10 TO 15 DEGS BELOW NORMAL. THE OVERALL DRY TREND IS BRIEFLY INTERRUPTED ON FRIDAY NIGHT INTO SATURDAY. LATEST LONG RANGE MODEL FCSTS CONTINUE TO INDICATE A CLIPPER LIKE SYSTEM DROPPING SOUTHEAST INTO THE REGION LATE FRIDAY NIGHT INTO SATURDAY THAT COULD CAUSE SOME LIGHT SNOW OR A WINTRY MIX DURING THAT TIME. THE PRECIPITATION TOTALS SHOULD BE LIGHT. OUR CURRENT FCST TRENDS INDICATE THIS WELL...SO NO ADJUSTMENTS NEEDED FOR THIS FCST. --21 && .PREV DISCUSSION... /ISSUED 1215 AM EST TUE FEB 13 2007/ AVIATION DISCUSSION (06Z TAFS)... AN AREA OF LOW PRESSURE WILL CONTINUE TO SLIDE EAST ALONG A STATIONARY BOUNDARY FROM OKLAHOMA CITY TO KNOXVILLE. SCATTERED RAIN NORTH OF THE BOUNDARY WILL CONTINUE TO AFFECT BOTH LEX AND SDF THROUGH THE EARLY OVERNIGHT HOURS (06-09Z)...WITH LESSER CHANCES AT BWG. CEILINGS MAY REMAIN AROUND MVFR OR VFR AT BWG WITH VSBY AROUND 3 TO 5SM...LOWER IFR CEILINGS MORE LIKELY AT BOTH SDF AND LEX WITH VSBY AS LOW AS 2SM IN RAIN. AFTER 09Z...THE SURFACE LOW WILL START TO MOVE MORE QUICKLY TOWARDS THE REGION WITH STEADY MODERATE RAINFALL OVERSPREADING ALL THREE TAF SITES BETWEEN 11Z AND 15Z (BWG AT 11Z....SDF AT 13Z AND LEX AT 15Z.) WINDS WILL INCREASE IN THE EVENING BECOMING MORE NORTHERLY AND GUSTY TOWARDS MIDNIGHT...WITH COLDER AIR POURING INTO THE REGION A BRIEF PERIOD OF FREEZING RAIN...SLEET OR SNOW WILL BE POSSIBLE TUESDAY EVENING AT EACH OF THE TAFS SITES. SCHOTT .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
259 AM EST TUE FEB 13 2007 .SHORT TERM /TODAY THROUGH WEDNESDAY/... A SIGNIFICANT WINTER STORM WILL AFFECT THE MID ATLANTIC REGION TODAY THROUGH EARLY WEDNESDAY. WHILE SOME SNOW WILL FALL AT THE BEGINNING OF THE STORM...SLEET AND FREEZING RAIN WILL BE THE PREDOMINANT PRECIPITATION TYPES AND WILL LIKELY LEAD TO SIGNIFICANT ICE ACCUMULATIONS. 06Z MSAS ANALYSIS INDICATED LOW PRESSURE NEAR 1005 MB MOVING INTO THE LOWER MISSISSIPPI VALLEY. A STATIONARY BOUNDARY EXTENDED EAST FROM THIS LOW INTO THE WESTERN ATLANTIC. ISENTROPIC LIFT CONTINUES TO STRENGTHEN OVER THE MID ATLANTIC WELL THE NORTH OF THIS BOUNDARY...AND IS SUPPORTING THE DEVELOPMENT OF PRECIPITATION OVER THE SOUTHERN PART OF OUR CWA. UPSTREAM OBSERVATIONS HAVE INDICATED A WINTRY MIX OF PRECIPITATION FALLING OVER WEST VIRGINIA. MODEL GUIDANCE MOVES LOW PRESSURE THROUGH THE TENNESSEE VALLEY AND INTO THE SOUTHERN APPALACHIANS THIS AFTERNOON. MEANWHILE...NEW LOW PRESSURE FORMS OFF THE SOUTHEAST COAST...AND BECOMES THE DOMINANT LOW ON WEDNESDAY AS IT MOVES UP THE MID ATLANTIC COAST. AS HAS BEEN THE CASE THE PAST FEW DAYS...THERE WILL BE PRECIPITATION THAT WILL PRODUCE HEALTHY AMOUNTS OF QPF...ON THE ORDER OF 1 TO 2 INCHES ACCORDING TO THE GFS AND NAM. HOWEVER...PRECIPITATION TYPE HAS BEEN VERY TRICKY...DUE TO OSCILLATING SOLUTIONS REGARDING HOW MUCH WARMER AIR ABOVE THE GROUND CAN MOVE NORTHWEST. LATEST GUIDANCE FROM THE GFS AND NAM BEGIN MOST OF THE PRECIPITATION THIS MORNING AS SNOW. THEN...WITH WARM AIR A FEW THOUSAND FEET ABOVE THE GROUND TILTING NORTH...SNOW WILL BEGIN TO MIX WITH AND CHANGE TO SLEET AND THEN FREEZING RAIN OVER THE HIGHLANDS...CENTRAL VIRGINIA AND LOWER SOUTHERN MARYLAND AREA. THE MIX AND CHANGEOVER WILL CONTINUE THIS AFTERNOON FURTHER NORTH...OVER THE DC/BALT METRO AREAS. CHANGEOVER WILL OCCUR THE LATEST OVER PARTS OF WESTERN MD. THERE MAY BE AN INCH OR TWO OF SNOW OVER DC/BALT AND AT LEAST 2 TO 4 INCHES OVER PARTS OF WESTERN MD IF NOT MORE...DUE TO THE SLOWER MIX AND CHANGEOVER TREND...AND WITH H7-H5 FN VECTOR DIVERGENCE INDICATING SOME BANDING POTENTIAL. TONIGHT...SLEET AND FREEZING RAIN WILL BE THE MAIN P-TYPES...YET LOCATIONS JUST SOUTH AND EAST OF DC MAY TURN TO ALL RAIN AS SURFACE TEMPERATURES RISE JUST ABOVE FREEZING. GFS AND NAM BUFKIT AND SREF P-TYPE ALGORITHMS SHOW SOME VARIABILITY...MAINLY WHETHER SLEET OR FREEZING RAIN WILL DOMINATE. CONTINUE SIDE WITH THE FREEZING RAIN SOLUTION...WITH SURFACE TEMPERATURES AOB 32 DEG F. SIGNIFICANT ICE ACCUMULATIONS WILL RESULT...AROUND 0.25 IN DC/BWI...WITH 0.50 OVER THE SHENANDOAH VALLEY. LESS THAN 0.25 WILL RESULT IN LOWER SOUTHERN MARYLAND DUE TO A SWITCH TO PLAIN RAIN. ON WEDNESDAY...AS LOW PRESSURE MOVES AWAY FROM THE COAST...PRECIPITATION WILL END. MIXED PRECIPITATION IN THE MORNING WILL TRANSITION BACK TO SNOW AS 850 MB TEMPERATURES DROP BELOW 0 DEG C. WITH THE SNOW TO SLEET TO FREEZING RAIN TO SNOW COMBINATION NOW THROUGH WEDNESDAY...WITH SOME SNOW ACCUMULATION IN ADDITION TO ICE ACCUMULATION GREATER THAN OR EQUAL TO 1/4 INCH...WINTER STORM WARNINGS WILL CONTINUE EXCEPT FOR LOWER SOUTHERN MARYLAND WHERE AN ADVISORY WILL CONTINUE WITH LESS THAN 1/4 INCH OF ICE EXPECTED DUE TO THE CHANGEOVER TO RAIN. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... THE EXTENDED WILL BE QUIET FOR THE MOST PART...UNTIL NEXT WEEKEND. THE MID LEVELS REMAIN FAIRLY ACTIVE DURING THE PERIOD...WITH SEVERAL SHORTWAVES DROPPING DOWN FROM CANADA AND A MAJOR LONGWAVE TROUGH MOVING THROUGH ON FRIDAY...FOLLOWED BY A SECOND ON SUNDAY. BY WEDNESDAY NIGHT...COASTAL LOW SHOULD BE NEAR CAPE COD AND THE FRONTAL BOUNDARY WELL OFFSHORE THE EASTERN SEABOARD. UPSLOPE SNOW SHOWERS ARE EXPECTED ALONG THE WESTERN RIDGES. THE UPSLOPE PRECIP LOOKS TO SHUT OFF SOMETIME LATE FRIDAY AS A HIGH PRESSURE RIDGE BUILDS IN FROM THE SOUTH. THE RIDGE AXIS IS EXPECTED TO MOVE OFFSHORE SATURDAY AS A LOW AND ASSOCIATED FRONTAL BOUNDARY APPROACHES FROM THE WEST. THE SURFACE LOW LOOKS TO PASS TO THE NORTH AND WEST AND THE FRONTAL BOUNDARY COME THROUGH LATE SATURDAY/EARLY SUNDAY. FOR NOW...THE GFS KEEPS THE HEAVIEST PRECIP TO THE WEST...BUT THE CHANCE POPS EVERYWHERE IN THE GRIDS STILL LOOKS GOOD. HAVE MADE JUST A FEW MINOR CHANGES OVERALL TO THE EXTENDED GRIDS. && .AVIATION /08Z-06Z/... EAST-WEST BAND OF RAIN/SNOW BUILDING NORTH INTO METRO HUBS IS COINCIDENT WITH ISENTROPIC LIFT ON THE 290-295K SURFACE. 06Z KIAD RAOB AND 0440Z KIAD ACARS SOUNDING INDICATE THAT THE THERMAL STRUCTURE WILL SUPPORT MORE SNOW THAN RAIN WITH THE NORTHWARD PROGRESS. CEILINGS MAY NEAR MVFR CATEGORY WITHIN THIS BAND. EXPECT DROP IN CEILINGS TO OCCUR BEHIND A COLD FRONT WHICH IS MOVING SOUTH FROM PENNSYLVANIA. WITH WARM ADVECTION ALOFT INCREASING THROUGH THE DAY...OVERRUNNING PRECIPITATION WILL BE DEVELOPING OVERHEAD. THERMAL WARM NOSE EXPECTED TO CHANGE PRECIPITATION OVER FROM SOLID TO FREEZING RAIN DURING THE MID AFTERNOON AND EVENING FROM SOUTHEAST TO NORTHWEST. PLEASE REFER TO TAFS FOR SPECIFIC TIMING. && .MARINE... SMALL CRAFT CONDITIONS ARE EXPECTED ON THE WATERS TODAY AS LOW PRESSURE APPROACHES THE MID ATLANTIC. THE SURFACE GRADIENT WILL FURTHER TIGHTEN ON WEDNESDAY AND WEDNESDAY NIGHT AS A COASTAL LOW MOVES UP THE EASTERN SEABOARD. BUFKIT SOUNDINGS ARE STILL SHOWING GALE GUST CRITERIA BEING MET...SO HAVE GONE AHEAD AND ISSUED THE HEADLINE. && .TIDES... CURRENT TIDAL DEPARTURES ARE A HALF FOOT BELOW ASTRONOMICAL PREDICTIONS. THE LUNAR CYCLE IS WANING (23 PERCENT FULL). BOTH THE CHESAPEAKE BAY OPERATIONAL FORECAST SYSTEM AND NOAA EXTRATROPICAL STORM SURGE MODELS DEPICT TIDES RETURNING TO THE ASTRONOMICAL PREDICTIONS THIS AFTERNOON. PRESSURE GRADIENT WILL TIGHTEN AHEAD OF THE STORM SYSTEM TODAY AND TONIGHT...ENCOURAGING TIDAL DEPARTURES TO INCREASE...MAXIMIZING SUNRISE WEDNESDAY WITH THE ARRIVAL OF THE DEEPENING STORM SYSTEM ACROSS THE MOUTH OF THE CHESAPEAKE BAY. WHILE ASTRONOMICAL TIDES ARE NEAR THE LOWEST FOR THE MONTH...TIDAL DEPARTURES WILL HAVE TO BE MONITORED THROUGH WEDNESDAY MORNING. A BLOWOUT IS FORECAST TO OCCUR WEDNESDAY AFTERNOON AND EVENING...WHEN TIDES MAY RUN A FOOT OR TWO BELOW ASTRONOMICAL PREDICTIONS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...WINTER STORM WARNING UNTIL 2 PM EST WEDNESDAY FOR DCZ001. MD...WINTER STORM WARNING UNTIL 2 PM EST WEDNESDAY FOR MDZ003>007- 009>011-013-014-501-502. WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 AM EST WEDNESDAY FOR MDZ016>018. VA...WINTER STORM WARNING UNTIL 2 PM EST WEDNESDAY FOR VAZ021- 025>031-036>042-050>056. WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 AM EST WEDNESDAY FOR VAZ057. WV...WINTER STORM WARNING UNTIL 2 PM EST WEDNESDAY FOR WVZ050>055- 501>504. MARINE...SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 4 AM EST WEDNESDAY FOR ANZ530>537. GALE WARNING FROM 4 AM WEDNESDAY TO 4 AM EST THURSDAY FOR ANZ530>537. && $$ SHORT TERM...PELOQUIN LONG TERM...LISTEMAA AVIATION/TIDES...ROGOWSKI MARINE...LISTEMAA/ROGOWSKI
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1040 PM EST WED FEB 14 2007 .UPDATE... MAIN FCST CONCERNS OVERNIGHT ARE LES TRENDS. WV IMAGERY AND RUC ANALYSIS INDICATED THAT THE SHRTWV LOBE FROM THE NRN ONTARIO MID/UPPER LEVEL LOW HAD SHIFTED INTO SE INTO E UPPER MI AND NRN LAKE MI. IR LOOP AND 01Z KSAW TAMDAR SNDGS SHOWED DEEP MOISTURE OVER THE AREA WITH DEWPOINT DEPRESSION AOB 4C TO 10K FT ALONG WITH 850 MB TEMP OF -23C AND 4K FT INVERSION HEIGHT. RADAR INDICATED THAT AS THE WINDS HAVE INCREASED THE SINGLE STRONG CONVERGENT BAND INTO THE MUNISING VCNTY HAD EVOLVED INTO WEAKER MULTIPLE WIND PARALLEL BANDS...MAINLY FROM MUNISING EASTWARD. THE RUC13 WHICH HINTS AT REDEVELOPMENT OF A MESO-LOW AND STRONGER BAND CONTINUING INTO KP53 SEEMS OVERDONE CONSIDERING 15-25 KT CBL FLOW OVER MOST OF THE LAKE OVERNIGHT. THE NAM HAD A REASONABLE GRASP OF WIND FIELD TRENDS ON E LAKE SUPERIOR AND SUGGESTS BEST 950 CONV WILL REMAIN FROM MUNISING TO GRAND MARAIS. FAVORABLE MOISTURE PROFILE WILL HELP OFFSET LESS THAN IDEAL SNOW GROWTH TEMPS. SO...GOING LES WARNING IS ON TRACK WITH ADDITIONAL 2-6 INCH AMOUNTS POSSIBLE OVERNIGHT. TO THE WEST...SHORTER FETCH WITH GROWING ICE COVER WILL LIMIT LES POTENTIAL WITH ONLY AN INCH OR TWO EXPECTED...MAINLY FOR AREAS WITH BEST LOW LVL CONV WITH 340 FLOW INCLUDING ERN ONTONAGON AND SRN HOUGHTON COUNTIES. .PREV DISCUSSION...ISSUED 345 PM EST WED FEB 14 2007 SHORT TERM...TONIGHT AND THURSDAY THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR LAKE EFFECT SNOW SHOWERS TONIGHT AND THURSDAY. WATER VAPOR IMAGERY AND RUC SHOWING AN ELONGATED CLOSED LOW OVER NORTHEAST ONTARIO EXTENDING SOUTHWEST INTO EASTERN LAKE SUPERIOR AND EMBEDDED IN A LONGWAVE TROUGH THAT COVERS MUCH OF EASTERN CANADA. A SHORTWAVE WRAPPING AROUND THIS LOW EXTENDS WEST ACROSS CENTRAL MINNESOTA INTO NORTH DAKOTA. A RIDGE ENCOMPASSES MUCH OF THE PACIFIC NORTHWEST AND THE CANADIAN ROCKIES. AT THE SURFACE A DOME OF HIGH PRESSURE IS LOCATED OVER NORTH DAKOTA WITH A RIDGE DROPS SOUTH FROM THE HIGH THROUGH THE CENTRAL PLAINS INTO TEXAS. AN 850MB THERMAL TROUGH OVER EAST CENTRAL ONTARIO AND WESTERN LAKE SUPERIOR IS PRODUCING LAKE-850MB DELTA-T`S OF AROUND 24C. RUC13 IS DOING ABOUT THE BEST OF ALL MODELS IN TRACKING A MESO LOW OVER SOUTH CENTRAL LAKE SUPERIOR SO WILL BE USING IF FOR TIMING. THE LOWEST INVERSION IS AROUND 3K FT OVER THE WEST AND 5.5KT OVER THE EAST PARTS OF LAKE SUPERIOR. CONVERGENCE AROUND THIS MESO LOW IS HELPING TO GENERATE LAKE EFFECT SNOWS OVER NORTH CENTRAL U.P. A NORTH WIND TO THE WEST OF THIS LOW CONTINUES TO DIRECT LAKE EFFECT SNOWS ACROSS ONTONAGON...HOUGHTON... AND KEWEENAW COUNTIES. THE SURFACE DEW POINTS NORTH OF LAKE SUPERIOR ARE VERY DRY AROUND -18F. THIS DRY AIR SHOULD LIMITS SOME OF LAKE EFFECT SNOW ACCUMULATIONS EXCEPT AROUND MUNISING WHERE THE HIRESWRF IS SHOWING A BAND PERSISTING THERE TONIGHT WHICH IS PLAUSIBLE. FOR THIS REASON...UPGRADED THE LES TO A LAKE EFFECT SNOW WARNING. THE MID LEVEL LOW WILL SHIFT INTO EAST CENTRAL ONTARIO TONIGHT AND INTO SOUTHERN QUEBEC ON THURSDAY...DRAGGING THE ACCOMPANYING SHORTWAVE INTO THE EASTERN U.P. BY SUNRISE AND INTO SOUTHEAST ONTARIO ON THURSDAY. THE SURFACE HIGH WILL CONTINUE TO SETTLE SOUTH INTO THE CENTRAL PLAINS ON THURSDAY. AS THE HIGH SETTLE SOUTH...THE THERMAL TROUGH WILL SLIDE INTO EAST CENTRAL ONTARIO OVERNIGHT AND INTO SOUTHERN QUEBEC ON THURSDAY. WITH THAT WARMER AIR IN THE FLOW AROUND THE BACK SIDE OF THE RIDGE WILL WORK ITS WAY INTO THE UPPER GREAT LAKES REGION BY LATE THURSDAY. THE DELTA-T`S WILL DECREASE TO TO AROUND 20C OVER LAKE SUPERIOR. RUC13 INDICATES THAT THE MESO LOW WILL SHIFT OVER GRAND MARAIS, MI TONIGHT AND GRADUALLY DISSIPATE ON THURSDAY AS IT MOVES TOWARDS YANJ. LOW LEVEL CONVERGENCE WILL BE FOCUSED MAINLY OVER IRON BAY TONIGHT AND HEAVY BANDS OF LES WILL REMAIN OVER ALGER COUNTY AND NORTHERN SCHOOLCRAFT COUNTIES. THUS WILL KEEP LAKE EFFECT SNOW ADVISORY GOING THROUGH THE PERIOD. LONG TERM...THU NIGHT ONWARD. NAM SHOWING A 500 MB TROUGH EAST OF THE AREA WITH A CLOSED LOW OVER NEW ENGLAND 00Z FRI WITH SHORTWAVE RIDGING ACROSS THE WESTERN HALF OF THE U.S. AND ACROSS THE NORTHERN PLAINS. THIS RIDGING MOVES IN FOR FRI BEFORE A SHORTWAVE AFFECTS THE AREA FOR FRI NIGHT AND SAT. NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE FOR FRI NIGHT AND SAT WITH DEEPER MOISTURE AVAILABLE TO WORK WITH. GFS IS FASTER AND FURTHER SOUTH WITH THIS SYSTEM THAN THE NAM IS AND WILL GO CLOSER TO THE GFS SOLUTION THAN THE NAM SINCE NAM HAS A BIAS OF SLOWER AND DIGS SYSTEMS FASTER THAN WHAT ACTUALLY OCCURS. NEXT CHANCE FOR SNOW WILL BE FRI NIGHT AND SAT WITH THE CLIPPER SYSTEM. FOR THU NIGHT...WILL PROBABLY NEED SOME TYPE OF HEADLINE FOR LUCE COUNTY AS WINDS TURN NW AND NAM BUFKIT SOUNDING SHOWS INVERSION HEIGHTS UP TO 6000 FEET AT THE BEGINNING OF THE EVENING...THEN WINDS TURN MORE WESTERLY LATE. COULD SEE AT LEAST 5 INCHES OF SNOW FOR THU NIGHT WITH THIS EVENT WITH LONG FETCH. WILL MENTION IN THE HWO. DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST. WENT CLOSE TO ADJMAV AND ADJMEN FOR TEMPERATURES. IN THE EXTENDED...GFS...ECMWF AND CANADIAN ALL SHOW THE 500 MB PATTERN CONSISTS OF A TROUGH ACROSS THE ERN U.S. 00Z SUN WITH RIDGING IN THE WEST. SHORTWAVE AFFECTS THE CWA 00Z SUN WITH THE TROUGH PUSHING EAST 00Z MON WITH RIDGING PUSHING INTO THE AREA THEN. UPPER FLOW THEN BECOMES ZONAL 00Z TUE WITH A WEAK SHORTWAVE PASSING NORTH OF THE AREA AND THEN ANOTHER SHORTWAVE AFFECTS THE AREA 00Z WED AND ANOTHER FOR 00Z THU. DID NOT MAKE TOO MANY CHANGES TO THE EXTENDED FORECAST...EXCEPT TO COOL THINGS DOWN SLIGHTLY ESPECIALLY SUNDAY AS ECMWF AND GFS BOTH SHOW ANOTHER COLD SNAP TO COME INTO THE AREA AND THEN SLOW MODIFICATION. UNDERCUT HPC GUIDANCE TEMPERATURES FOR HIGHS AND WENT CLOSE TO ADJMEX AND ADJMEN TEMPERATURES FOR HIGHS IN THE EXTENDED WITH TEMPERATURES NEAR NORMAL TOWARDS MID WEEK. WENT WITH CHANCE POPS FOR MON NIGHT AND TUE WITH A SYSTEM MOVING THROUGH AND KEPT LAKE EFFECT IN FOR SUN. WENT DRY AT OTHER TIMES. && .MQT WATCHES/WARNINGS/ADVISORIES... HEAVY FREEZING SPRAY WARNING FOR LAKE SUPERIOR. LAKE EFFECT SNOW WARNING THROUGH 7 PM MIZ001. LAKE EFFECT SNOW WARNING TNGT-THU EVENING MIZ006-085. && $$ JLB...UPDATE DLG...SHORT TERM GJM...LONG TERM
FORECAST DISCUSSION CONCERNING THE IMPACT TO THE FORECAST BY A
CHANGE IN TRACK IS CERTAINLY RIGHT ON. DEPTH OF MOISTURE IS IMPACTED
ENOUGH FROM THIS SLIGHT SOUTHWARD ADJUSTMENT TO WHERE THERE IS A SLOWER MOISTENING TO THE 850-700MB LAYER THROUGH THE DAY...AND NOW SYNOPTIC SNOWFALL IS NOT EVEN EXPECTED TO BE REALIZED DUE TO TOO MUCH DRY AIR BETWEEN 850-700MB. THIS LEAVES OVER LAKE INSTABILITY AND HEAT/MOISTURE FLUX OFF THE WATER AS THE PRIMARY PRECIPITATION PRODUCING MECHANISM. FORECAST SOUNDINGS SHOW INVERSION HEIGHTS MAYBE GETTING INTO THE 3500 FOOT RANGE WITH TEMPS AT THE TOP OF THIS MIXED LAYER AROUND -18C...WHILE WINDS CONTINUE TO VEER AROUND TO ENE ACROSS LAKE HURON. SO...MAYBE SOME DECENTLY-SIZED FLAKES CAN DEVELOP...BUT AMOUNT OF THEM IS IN SOME QUESTION...WITHOUT GREATER MOISTURE REACHING INTO TEMPS COLDER THAN -18C. WITH LITTLE TO NO HELP ALOFT FOR THE MAJORITY OF THE DAY (UNTIL LATE AFTERNOON)... ACCUMULATIONS OF A FEW TENTHS STILL LOOKS GOOD...AND SEE NO REASON TO SWAY FROM THIS FORECAST RIGHT NOW. FROM A CHANCE OF PRECIPITATION STANDPOINT...SINCE IT IS ALREADY LIGHT SNOWING AT OSCODA AND ROGERS CITY...WITH BEST INSTABILITY/MOISTURE DEVELOPING INTO DAYBREAK...AND LARGE OVER-LAKE TRAJECTORIES CONNECTING LAKE HURON INTO GEORGIAN BAY VIA THE MAIN CHANNEL...WILL EXPAND 30-40% FOR SCATTERED SNOW SHOWERS INTO FROM ROGERS CITY TO STURGEON POINT AND STANDISH. LITTLE FETCH ACROSS WHITEFISH BAY FOR NO MENTION OF SNOW...EVEN FLURRIES. TEMPERATURES GET OFF TO QUITE THE CHILLY START IN MANY AREAS WITH READINGS IN THE 0 TO -10F RANGE...-10 TO -20 IN PARTS OF EASTERN UPPER AND FAR NRN LOWER (LOWER ELEVATIONS). HIGHS WILL TOP OUT IN THE TEENS MOST PLACES...WITH TEMPS STRUGGLING TO REACH 10F IN PORTIONS OF EASTERN UPPER. TONIGHT...1000-850MB FLOW BACKS TO DUE NE MOST AREAS...AND THEN SLIGHTLY EAST OF NORTH BY 12Z...AS SFC LOW DEEPENS/RE-DEVELOPS NEAR THE MARYLAND COAST. ALTHOUGH H8-H5 MOISTURE DEEPENS TO 80-90% ACROSS THE FAR SE CWA NEAR THE SAG BAY...MOST OF IT`S RESIDENCE TIME OVER THE AREA WILL BE SPENT TRYING TO MOISTEN THE AFOREMENTIONED 850-700MB LAYER. INVERSION HEIGHTS DO NOT SWAY TOO FAR FROM 3500 FEET OR SO...AND H8 TEMPS REMAIN IN THE UPPER TEENS BELOW ZERO. LONGEST FETCHES ACROSS LAKE HURON BRING BEST LES CLOSER TO THE COAST FROM STURGEON POINT TO STANDISH...ALTHOUGH THE NORTH CHANNEL COULD BRING A NARROW BAND OF LIGHTER SNOWS TO PRESQUE ISLE AND POSSIBLY MONTMORENCY COUNTIES. SYNOPTICALLY...AGAIN...SNOW WILL LIKELY AID THE SHALLOW LES EXPECTED ACROSS THE SE CWA...BUT THERE IS NOT EXPECTED TO BE MUCH IN THE WAY OF ACCUMULATIONS FROM A SYSTEM PERSPECTIVE. ALL-IN-ALL...MAYBE 1-2 INCHES ACROSS THIS AREA. AS WINDS SHIFT MORE NORTH OVERNIGHT...COLD UPPER LOW SITTING IN ONTARIO WILL ROTATE SOUTHWARD INTO NRN LAKE SUPERIOR AND 900-700MB MOISTURE WILL BE ON THE RISE...BUT REMAINING BELOW 50%. FAR WESTERN CHIP/MACK COUNTIES OF EASTERN UPPER...AND GTV BAY SOUTHWARD COULD SEE SCATTERED LIGHT SNOW SHOWERS THAT WILL BE OCCURRING ALONG THE LEELANAU COAST...WILL MOVE INLAND. AMOUNTS WILL BE MINIMAL AT BEST. WEDNESDAY...UPPER LOW DROPS INTO FAR EASTERN LAKE SUPERIOR WITH TROUGH AXIS SWINGING DOWN INTO NRN LAKE MICHIGAN. BRIEF SWATH OF MODEST H7-H5 -DIVQ ARRIVES...1000-850MB WINDS TURN FROM NORTH TO NNW WHILE 900-700MB MOISTURE INCREASES TO 80-90% AND H8 TEMPS LOWER TO -20C TO -22C. INVERSION HEIGHTS WILL BE ON THE RISE...RANGING FROM 4KFT IN EASTERN UPPER TO AS HIGH AS 6KFT AROUND GTV BAY. NICE LAKE SUPERIOR TAP ARRIVING IN GTV BAY...WITH SMALLER FETCH FOR EASTERN UPPER. MAYBE UP TO AN INCH FOR THE GTV BAY REGION...WITH A FEW TENTHS IN WESTERN CHIP/MACK...AND ACROSS NE LK HURON COAST AROUND ROGERS CITY. BETTER ACCUMULATIONS HOLDING OFF UNTIL WEDNESDAY NIGHT AND THURSDAY. MARINE...WILL ISSUE SMALL CRAFT ADVISORIES THROUGH WEDNESDAY NIGHT FOR MANISTEE TO SLEEPING BEAR POINT...AND FOR PRESQUE ISLE LIGHT SOUTHWARD FOR 10-20KT WINDS WITH GUSTS REACHING 25 KNOTS DUE TO LOCAL EFFECTS SUCH AS FUNNELING AND COASTAL CONVERGENCE. OTHER AREAS ARE LIKELY TO BE ADDED TO THIS ADVISORY IN LATER PERIODS AS WINDS TURN MORE NW. WEDNESDAY NIGHT...CLOSED UPPER LOW MOVES ACROSS THE NORTHERN GREAT LAKES. AS IT DOES SO...1000-850MB WINDS STAY LOCKED IN AT THE NNW DIRECTION WITH 900-700MB RH EXCEEDING 80 PCT. INVERSION HEIGHTS ALSO REMAIN RELATIVELY STEADY AROUND 6.0KFT. THIS POINTS TO A COUPLE OF INCHES OF SNOW IN THE NNW FLOW BELT AROUND TVC/KALKASKA/ MANTON...WITH LIGHTER AMOUNTS OUTSIDE THIS AREA...INCLUDING AROUND WHITEFISH POINT WHERE THE SHORTER FETCH WILL LIMIT ACCUMULATIONS. TO THE EAST OF THE NNW SNOW BELT...MODEL SOUNDINGS DO NOT SHOW MUCH SYNOPTIC MOISTURE TO PRODUCE SIGNIFICANT ACCUMULATIONS...WITH 700-500MB RH BETWEEN 40-60 PCT FOR MUCH OF THE NIGHT. LOW TEMPERATURES WILL NOT BE NEARLY AS COLD AS THE PREVIOUS NIGHTS WITH THE CLOUD COVER...BUT WILL COULD REACH JUST BELOW ZERO AT THE TYPICAL COLD SPOTS. THURSDAY AND THURSDAY NIGHT...THE UPPER LEVEL LOW STARTS OUT NEAR TORONTO TO START THE DAY AS IT CONTINUES ITS JAUNT EAST. PLENTY OF 900-700MB RH IN EXCESS OF 90 PCT WITHIN CYCLONIC FLOW THROUGH THE COLUMN WILL BE PRESENT ALL DAY BEFORE RIDGING MOVES IN OVERNIGHT WHICH HELPS TO SCOUR OUT THE MOISTURE. WITH NNW WINDS QUICKLY BACKING TO NW AND REMAINING SO OVER THE PERIOD...INVERSION HEIGHTS OF ABOUT 5.5KFT-6.0KFT LINGER FOR MOST OF THE DAY BEFORE THE RIDGING QUICKLY SQUASHES IT TO UNDER 3KFT BY 12Z FRI. 850MB TEMPS ALSO QUICKLY REBOUND BETWEEN -12C TO -14C BY 12Z FRI. AREAS WITHIN THE NW FLOW SNOWBELT THEREFORE STANDS TO GET THE MOST SNOW AND A FEW INCHES IS CERTAINLY WITHIN REASON OVER THIS PERIOD...WITH THE BULK OF THE ACTIVITY OCCURRING DURING THE DAY. FRIDAY AND FRIDAY NIGHT...LOW LEVEL RIDGING TEMPORARILY ESTABLISHES ITSELF ON FRIDAY...DROPPING 900-700MB RH FROM 50 PCT TO 20 PCT BY EARLY AFTERNOON. WINDS ALSO BACK FROM THE WNW TO SOUTHWEST IN RESPONSE TO THE NEXT CLIPPER MOVING QUICKLY ACROSS THE GREAT PLAINS. WILL LEAVE LOW CHANCY POPS ACROSS NW LOWER FOR FRIDAY... EVEN THOUGH MUCH OF THE LES ACTIVITY SHOULD DIE BY AFTERNOON IF NOT BEFORE. 850MB TEMPS WARM TO THE -10C TO -13C RANGE...BUT WITH LOW MIXING HEIGHTS...HIGHS WILL ONLY REACH INTO THE 20S. THAT AFOREMENTIONED CLIPPER DIVES ACROSS THE MISSOURI RIVER VALLEY OVERNIGHT PER ECMWF/CANADIAN AND THINK THE GFS IS TOO FAR NORTH. NONETHELESS...WEAK UPPER LEVEL TROUGH AND ASSOCIATED SURFACE COLD FRONT APPROACH THE AREA BY LATE FRIDAY NIGHT WHICH IS CLOSE ENOUGH FOR ME TO KEEP A LOW CHANCE FOR LIGHT SNOW OVER THE ENTIRE AREA FRIDAY NIGHT. SATURDAY AND SATURDAY NIGHT...COLD FRONT PASSES ACROSS THE AREA ON SATURDAY WITH NOT AS MUCH COLD AIR BEHIND IT AS THE PREVIOUS SYSTEM...BUT STILL PLENTY COLD FOR LAKE EFFECT SNOW SHOWERS OVER THE TYPICAL BELTS. SHARP LOW LEVEL CYCLONIC FLOW WILL MAKE IT DIFFICULT TO PINPOINT AN AREA FOR THE HIGHEST CHANCE OF PRECIP AT THIS TIME...SO WILL BROAD BRUSH AREAS ACROSS NW LOWER AND EASTERN UPPER. LAKE EFFECT SNOW SHOWERS WILL CONTINUE INTO SATURDAY NIGHT. HIGH TEMPERATURES MAY ACTUALLY APPROACH NORMAL ON SATURDAY...BEFORE THE COLDER AIR ARRIVES. MPC && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
701 AM CST TUE FEB 13 2007 .DISCUSSION... THE 00Z SHORT-TERM MODELS (TIL THURSDAY NIGHT)...MODELS...DESPITE BEING THE MIDST OF A MAJOR WINTER STORM NOW AFFECTING THE BI- STATE...CONTINUE TO HAVE DIFFERENCES IN MASS FIELDS REGARDING THE STORM AS WELL AS TIMING ISSUES. THE GFS CONTINUES TO MOVE THE SYSTEM RATHER FAST WHILE THE NAM IS SLOWER. PREFER THE NAM...AS THIS MODEL HAS BEEN SUPERIOR THROUGHOUT THIS STORM WITH THE GFS CONTINUALLY PLAYING CATCH UP...AS IT WAS THE NAM THAT ACCURATELY PREDICTED PCPN HOLDING OFF TIL MONDAY MORNING WITH PCPN LINGERING THRU TUESDAY ABOUT 24HRS BEFORE THE GFS DID. ONCE AGAIN...THE NAM SHOWS A SLOWING DOWN OF THIS SYSTEM...WITH PCPN EXPECTED TO NOW LINGER INTO THE EVENING FOR THE ERN PORTIONS OF THE FA. THE GFS ALSO SHOWS THIS...BUT TO A LESSER EXTENT. SOME ITEMS THAT THE MODELS DO AGREE ON IS THAT THE OLD DEFORMATION ZONE OVER FAR NRN MO/SRN IL AND INTO ERN KS IS FADING WITH A NEW DEFORMATION ZONE TAKING SHAPE OVER THE I-70 CORRIDOR. THE STORM ITSELF IS SPLIT IN TWO ATTM DUE TO AN EVOLVING SPLIT FLOW PATTERN...WITH THE SRN STREAM SYSTEM SLIDING THRU FAR WRN AR AND THE NRN STREAM AFFECTING THE ERN SECTIONS OF NEB. THE SRN STREAM MID LEVEL SYSTEM WILL MOVE THRU BETWEEN LATE MORNING AND EARLY AFTERNOON FROM WEST TO EAST...WITH CSI POTENTIAL INDICATED ALONG THE SRN PERIPHERY OF ITS CONVERGENCE AXIS (DEFORMATION ZONE) JUST S OF THE I-70 CORRIDOR WHERE SOME THUNDERSNOW NOT OUT OF THE QUESTION AS SRN STREAM VORT MAX PASSES JUST S OF KSTL AT THIS TIME. AS SYSTEM DEFORMATION AXIS FULLY DEVELOPS...THE NRN STREAM SYSTEM THEN EXPECTED TO MAKE AN IMPACT...ALTHOUGH TO A LESSER EXTENT THAN THE SRN STREAM WITH LESS MOISTURE TO WORK WITH AND AN EXITING SYSTEM TO THE E. BELIEVE MAIN IMPACT OF NRN STREAM SYSTEM WILL BE TO PROLONG THE MEASURABLE PCPN CHANCES THRU THIS EVENING FOR MANY AREAS...ALTHOUGH ACTUAL ADDITIONAL SNOW AMOUNTS WILL BE MINIMAL. PREFER THE NAM SOUNDINGS AND THEIR DEPICTIONS OF P-TYPES WITH THIS STORM...WHICH ERODES THE WARM WEDGE AT A SLOWER RATE THAN THE GFS...AND THIS SEEMS TO BE VERIFYING BETTER SO FAR. LOOK FOR A CHANGEOVER TO ALL SNOW IN MOST OF MID-MISSOURI BY 12Z...FOR THE NWRN HALF OF THE STL METRO AREA BETWEEN 12-15Z...THE SERN HALF OF THE STL METRO AREA AND MUCH OF SWRN IL BETWEEN 15-18Z...AND SRN IL AND SERN MO SOME TIME THIS AFTERNOON. ONCE THE CHANGEOVER OCCURS IN THE AREA OF THE DEF ZONE AXIS WHICH IS EXPECTED TO BE INVOF THE I-70 CORRIDOR...SNOWFALL RATES OF 1 INCH AN HOUR WILL BE EXPECTED WITH BRIEFLY HIGHER RATES POSSIBLE LATER THIS MORNING. OVERALL... AM EXPECTING SIMILAR SNOWFALL AMOUNTS FROM THE PREVIOUS FORECAST... WITH A SLIGHT TEMPERING OF VALUES IN CENTRAL MO WHERE RATHER LONG TIME FOR CHANGEOVER TO OCCUR WILL COST THEM VALUABLE TIME IN SNOW AMOUNTS. SHOULD SEE...BY SUNSET TONIGHT...5-8 INCHES FOR THE NRN THIRD OF THE FA...3-6 INCHES FOR THE CNTRL THIRD...AND LESS THAN 3 INCHES FOR THE SRN THIRD. BLOWING/DRIFTING SNOW WILL BE A CONCERN THRU TONIGHT WITH HIGH WINDS. OTHERWISE...SECONDARY FORECAST PROBLEM IS TEMPS. TEMPS TO FALL THRU THE DAY TODAY WITH MAXES LIKELY AROUND 12Z OR SO. USED A BLEND OF MAV/MET WHICH SEEMED TO BE VERIFYING WELL SO FAR AND HAD A GOOD HANDLE ON EXPECTED TRENDS. AFTER TODAY...PREFERRED AOB THE COLDEST MOS NUMBERS IN AREAS EXPECTED TO GET SEVERAL INCHES OF SNOW...ALTHOUGH ADJUSTMENTS NOT AS GREAT TONIGHT DUE TO CLOUDS LINGERING. TES && .AVIATION... FOR THE 12Z TAFS...ETA BUFKIT SNDGS VERIFYING BEST WITH PTYPE OVRNGT. USING THIS FOR STL AREA TAF SITES REVEALS CHGOVR TO ALL SNOW SHUD OCR ARND 14Z. THIS MAY STILL BE A BIT FAST AS ACARS DATA FROM A 10Z FLIGHT BTWN KSTL-KRFD AT 1045Z REVEALED A FAIRLY PRONOUNCED WRM LYR WITH MAX TEMP OF 2.8C ARND 6KFT...BUT HRLY ETA BUFKIT DID SUGGEST A SIMILAR LYR THAT RPDLY COOLS BY 14Z. HVIEST SNOWFALL OVR THE NXT 6 HRS WL BE LOCATED FROM JUST E OF KCOU TO NR KPPQ...WITH THIS PCPN AREA BRINGING OCNL +SN TO KUIN TAF. BLV THAT FOR MOST LOCATIONS THE MOST SGFNT PCPN WL OCR BTWN NOW AND 18Z...ALTHO WITH SCNDRY SHTWV DROPPING INTO SYS FROM E NE SM LGTR PCPN WL UNDOUBTEDLY EXIST INTO LT AFTN/ERY EVE. WITH STG N SFC WNDS WITH GUSTS NR 30KTS ALSO CONTD MENTION OF BLSN...ALTHO PRIMARY THRT OF THIS WL PROB BE IN THE LOCATIONS WITH THE HVIST SNOWFALL THIS MRNG AND COLDEST TEMPS THIS AFTN...KUIN AND KCOU. TRUETT && .LSX WATCHES/WARNINGS/ADVISORIES... MO...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR CRAWFORD-JEFFERSON-WASHINGTON. WINTER STORM WARNING UNTIL 6 PM CST THIS AFTERNOON FOR FRANKLIN- GASCONADE-KNOX-LEWIS-LINCOLN-MARION-MONROE-MONTGOMERY-PIKE- RALLS-SHELBY-ST. CHARLES-ST. LOUIS-ST. LOUIS CITY-WARREN. WINTER STORM WARNING UNTIL 3 PM CST THIS AFTERNOON FOR AUDRAIN- BOONE-CALLAWAY-COLE-MONITEAU-OSAGE. IL...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR CLINTON IL-MARION IL-MONROE IL-ST. CLAIR IL-WASHINGTON IL. WINTER STORM WARNING UNTIL 6 PM CST THIS AFTERNOON FOR ADAMS IL- BOND IL-BROWN IL-CALHOUN IL-FAYETTE IL-GREENE IL-JERSEY IL- MACOUPIN IL-MADISON IL-MONTGOMERY IL-PIKE IL. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
914 PM MST WED FEB 14 2007 .UPDATE... ADJUSTED A FEW TEMPS DOWN OVER THE E OVERNIGHT AS WELL AS INCREASED POPS AND SNOW AMOUNTS EVER SO SLIGHTLY. FIRST WAVE OF ENHANCED SNOW HAS NOW SHIFTED S OF OUR FORECAST AREA SRN BORDER. NEXT AREAS OF SNOW OVER THE NRN MOUNTAINS AND NE HIGHLANDS AND ARE DRIFTING S AND SSE. SNOW TO CONTINUE TO AFFECT MUCH OF THE E THROUGH THE NIGHT. 40 && .PREV DISCUSSION...248 PM MST WED FEB 14 2007 18Z SURFACE ANALYSIS SHOWS A STATIONARY BOUNDARY DRAPED SOUTH TO NORTH ALONG THE CENTRAL MOUNTAIN CHAIN WITH A 1040MB HIGH PRES AREA BUILDING DOWN THE CENTRAL HIGH PLAINS INTO THE E PLAINS OF NM. LATEST WATER VAPOR LOOP SHOWS THE SOUTHERN STREAM SHEARED TROUGH AXIS OVER NM TRANSLATING EASTWARD AS A 150-170 KNOT JET SCREAMS EASTWARD INTO TEXAS OUT OF NORTHERN MEXICO...AS INDICATED BY 400-200MB AIRCRAFT WINDS. A NORTHERN STREAM UPPER TROUGH OVER THE CENTRAL HIGH PLAINS IS DROPPING SOUTH TOWARD THE FRONT RANGE. 12Z MREF/15Z SREF GUIDANCE IN GOOD AGREEMENT WITH THE 500MB HEIGHT PATTERN ON THE TIMING OF THE EXITING SOUTHERN STREAM TROUGH TONIGHT INTO THURSDAY AFTERNOON. 12Z NAM/GFS INDICATING SNOWFALL WILL EXIT THE FORECAST AREA WEST OF THE CENTRAL MTN CHAIN THIS EVENING BUT LINGER OVER THE SANGRES...ESTANCIA VALLEY...AND ESPECIALLY THE SACRAMENTO MOUNTAINS AND SOUTHEAST PLAINS THROUGH THURSDAY MORNING. INTERESTINGLY...BOTH MODELS SHOW AN AREA OF SNOW BLOSSOMING OVER THE NORTHERN MTNS THIS EVENING AND PRESSING SOUTH AND EAST THROUGH THE OVERNIGHT HOURS. LATEST IR SATELLITE IMAGERY LATE THIS AFTERNOON DOES INDEED SHOW CLOUD TOPS COOLING OVER SOUTH CENTRAL COLORADO. HPC SNOWFALL ACCUMULATION GRAPHICS ALSO INDICATE THE POTENTIAL FOR ANOTHER 1 TO 2 INCHES OF SNOWFALL OVER PORTIONS OF THE E PLAINS WITH 2 TO 4 INCHES IN THE SANGRES AND SACRAMENTO MTNS. DECIDED TO EXTEND HIGHLIGHTS EAST OF THE CENTRAL MTNS THRU 4AM THURSDAY EXCEPT THE FAR NE CORNER. 12Z NAM CROSS SECTION ALONG THE CENTRAL MTNS SHOWS DECENT LOW LEVEL VERTICAL VELOCITY ABOVE WEAK LOW LEVEL FRONTOGENESIS AND SATURATED EPV...SO CANNOT RULE OUT A FEW MORE INCHES OF SNOW FROM LIGHT TO MODERATE SNOW BANDS OVERNIGHT. EXPECT CLEARING SKIES ACROSS THE REMAINDER OF THE FORECAST WEST OF THE CENTRAL MTNS WITH VERY COLD TEMPS TONIGHT. WENT SEVERAL DEGREES BELOW MOS GUIDANCE EVERYWHERE. WILL ALSO ADD PATCHY FOG IN VALLEY AREAS. BEYOND THURSDAY...MODELS SHOWING A SLOW WARMING TREND WITH CLEAR TO PARTLY CLOUDY SKIES ACROSS THE STATE THROUGH THE WEEKEND AS A RIDGE BUILDS OVER THE SW CONUS. ANOTHER WEAK SOUTHERN STREAM SYSTEM TRIES TO MOVE NORTHEAST INTO THE RIDGE LATE SUNDAY...BUT THIS MAY BE MAINLY CLOUDS. && .ABQ WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 4 AM MST THURSDAY FOR THE FOLLOWING ZONES...NMZ004-005-010>013-016-017-026. WINTER WEATHER ADVISORY UNTIL 4 AM MST THURSDAY FOR THE FOLLOWING ZONES...NMZ018>021. && $$ GUYER
AREA FORECAST DISCUSSION...CORRECTED
NWS ALBUQUERQUE NM
215 PM MST TUE FEB 13 2007 .DISCUSSION... 18Z SFC ANALYSIS SHOWS A STNRY BOUNDARY DRAPED SOUTH TO NORTH ACROSS CENTRAL NM. THIS SEPARATES VERY COLD AIR OVER THE E PLAINS FROM MILD AIR TO THE WEST. LATEST WV/IR SAT IMAGERY SHOWS A TROUGH AXIS ELONGATED NORTHWEST TO SOUTHEAST ACROSS AZ AND NM WITH A DRY SLOT MOVING EAST ACROSS NORTHERN SONORA AND CHIHUAHUA. A FEW LIGHTNING STRIKES WERE ALSO NOTED ALONG THE EDGE OF THE DRY SLOT. LATEST 400-200MB AIRCRAFT WIND DATA SHOWS A WEST TO EAST 140-160 KNOT JET OVER NORTHERN MEXICO. CURRENT RADAR TRENDS SHOW AN AXIS OF LIGHT TO MODERATE RAIN/SNOW OVER SW NM MOVING NORTHEAST INTO THE RIO GRANDE VALLEY AND CENTRAL MOUNTAIN CHAIN. 12Z MREF AND 15Z SREF GUIDANCE SHOWING EXCELLENT RUN TO RUN AND INTERMODEL CONSISTENCY WITH THE 500MB HEIGHT PATTERN THROUGH 12Z THURSDAY. 12Z NAM/GFS/UKMET ALSO IN VERY GOOD AGREEMENT WITH THE GENERAL 500MB...SURFACE...AND PRECIP PATTERN WITH THE UPCOMING WINTER STORM. SIDED WITH HPC ON THE SNOWFALL ACCUMULATIONS ACROSS THE FORECAST AREA. UPGRADED TO WINTER STORM WARNING FOR THE CENTRAL HIGHLANDS...SANGRE DE CRISTOS...SANDIA AND MANZANOS...SACRAMENTOS... AS WELL AS THE ALBUQUERQUE METRO AREA. MODEL SOLNS INDICATE THAT THE VORTICITY AXIS AND ASSOCIATED RAIN/SNOW WILL CONTINUE TO TRANSLATE SLOWLY NORTH AND EAST THROUGH THE OVERNIGHT PERIOD INTO WEDNESDAY AFTERNOON AS THE 500/700MB OPEN WAVES PUSH EAST WITH A STRENGTHENING UPPER LEVEL JET. NAM/GFS SHOWING LAPSE RATES ON THE ORDER OF 7-8C/KM OVERNIGHT WITH LIFTED INDICES NEAR -1C OVER THE SOUTHERN HALF OF CWA. CANNOT RULE OUT OF FEW THUNDERSTORMS PUSHING NORTH ACROSS THE SOUTHERN AND CENTRAL PORTIONS OF THE CWA THIS EVENING. EAST WINDS ACROSS THE ALBUQUERQUE METRO AREA THIS AFTERNOON WILL LIKELY LEAD TO ENHANCED CONVERGENCE TO THE WEST OF THE CITY THIS EVENING. MODEL CROSS SECTIONS SHOW STRONG LOW LEVEL FRONTOGENESIS AND LOW LEVEL SATURATED EPV WILL COUPLE WITH MODERATE MID AND UPPER LEVEL DIVERGENCE ACROSS THE CENTRAL MOUNTAINS TO PRODUCE SIGNIFICANT SNOWFALL OVER THE JEMEZ...SANDIA AND MANZANOS...AND THE SOUTHERN PORTIONS OF THE SANGRES OVERNIGHT. SINCE MOST OF THE SNOWFALL WILL LIKELY FALL OVERNIGHT HAVE SIDED WITH A WINTER STORM WARNING FOR THE ALBUQUERQUE METRO AREA. THINK MOST ACCUMULATIONS WILL BE CONFINED TO GRASSY AND ELEVATED SURFACES FOR A FEW HOURS BEFORE TEMPS COOL ENOUGH FOR ACCUMULATION ON ROADWAYS. WILL KEEP WINTER STORM WATCH FOR THE E CENTRAL PLAINS SINCE UNCERTAINTY IS STILL A LITTLE HIGH THERE. GOING WITH ADVISORIES FOR THE GILA... LOWER RIO GRANDE VALLEY...AND NORTHWEST PLATEAU. WINTER STORM WILL SLOWLY TRANSLATE EAST INTO THE E PLAINS EARLY WEDNESDAY AS THE UPPER LEVEL JET MOVES EAST INTO TEXAS. SKIES SHOULD CLEAR FROM WEST TO EAST DURING THE DAY WEDNESDAY. CHILLY TEMPS ARE LIKELY WEDNESDAY NIGHT UNDER CLEAR SKIES AND SNOW COVER ESPECIALLY ACROSS THE WESTERN HALF OF THE STATE. QUIETER WEATHER PATTERN WILL WORK INTO THE STATE FOR THE END OF THE WEEK AND AT LEAST THE FIRST HALF OF THE WEEKEND. && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 27 40 20 42 / 60 30 5 0 GALLUP.......................... 26 35 14 38 / 70 50 5 0 GRANTS.......................... 25 34 12 37 / 80 50 10 0 GLENWOOD........................ 29 46 23 52 / 30 50 10 0 CHAMA........................... 13 29 1 31 / 70 50 10 10 LOS ALAMOS...................... 19 32 13 33 / 80 60 10 0 RED RIVER....................... 10 22 -1 25 / 60 60 20 10 TAOS............................ 21 30 10 33 / 70 50 20 5 SANTA FE........................ 24 31 15 33 / 90 60 20 0 SANTA FE AIRPORT................ 25 32 17 34 / 90 60 20 0 ESPANOLA........................ 24 38 20 39 / 70 50 20 0 ALBUQUERQUE HEIGHTS............. 30 35 25 40 / 90 60 20 0 ALBUQUERQUE VALLEY.............. 31 36 23 41 / 90 60 20 0 ALBUQUERQUE FOOTHILLS........... 29 33 22 36 / 90 50 20 0 ALBUQUERQUE WEST MESA........... 30 34 24 39 / 90 50 20 0 SOCORRO......................... 32 42 26 50 / 70 60 20 0 SANDIA PARK/CEDAR CREST......... 23 30 15 32 / 90 60 20 0 MORIARTY/ESTANCIA............... 22 32 19 35 / 90 60 20 0 CARRIZOZO....................... 28 40 25 45 / 70 40 20 0 RUIDOSO......................... 25 30 19 39 / 70 60 30 5 RATON........................... 16 24 7 33 / 80 60 30 0 LAS VEGAS....................... 17 25 9 30 / 80 60 40 0 ROY............................. 14 21 12 35 / 60 60 40 10 CLAYTON......................... 13 18 10 33 / 60 60 30 20 SANTA ROSA...................... 22 31 19 37 / 70 60 40 10 TUCUMCARI....................... 23 28 15 34 / 60 60 40 20 FORT SUMNER..................... 22 32 20 37 / 60 70 40 20 CLOVIS.......................... 23 29 20 35 / 60 60 50 20 PORTALES........................ 22 30 19 36 / 60 60 50 20 ROSWELL......................... 29 36 25 42 / 70 30 40 10 && .ABQ WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM MST WEDNESDAY FOR THE FOLLOWING ZONES...NMZ002>013-016-017-026. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM MST WEDNESDAY FOR THE FOLLOWING ZONES...NMZ001. WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE WEDNESDAY NIGHT FOR THE FOLLOWING ZONES...NMZ018-020-021. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM MST WEDNESDAY FOR THE FOLLOWING ZONES...NMZ014-015. && $$ GUYER
AREA FORECAST DISCUSSION
NWS PORTLAND OR
230 PM PST WED FEB 14 2007 .SYNOPSIS..A WARM FRONT WILL CONTINUE TO BRING RAIN ACROSS THE REGION THROUGH EARLY EVENING. A STRONGER...MOISTURE LADEN FRONT WILL MOVE INTO THE AREA LATER TONIGHT THROUGH THURSDAY EVENING BRINGING HEAVY RAIN TO THE AREA...THEN SHIFT TO THE SOUTH EARLY FRIDAY. HIGH PRESSURE WILL MOVE INTO THE AREA FRIDAY AND SATURDAY FOR DRY AND MILD CONDITIONS. THE NEXT FRONT IS EXPECTED TO MOVE INTO THE AREA ON SUNDAY. && .SHORT TERM...THE FIRST IN A PAIR OF FRONTAL SYSTEMS IS MOVING ACROSS THE REGION THIS AFTERNOON AND WILL CONTINUE TO BRING RAIN TO THE AREA THROUGH EARLY EVENING. SATELLITE AND RADAR SHOW A BACK EDGE TO THE FIRST FRONTAL BAND...SO WILL LIKELY SEE A DECREASE IN RAINFALL FOR A FEW HOURS THIS EVENING BEFORE THE NEXT SLUG OF MOISTURE ARRIVES AROUND MIDNIGHT. A STRONGER AND MUCH WETTER FRONT IS POISED TO MOVE IN LATER TONIGHT AND REMAIN OVER THE AREA THROUGH THURSDAY EVENING. THIS SYSTEM HAS A VERY MOIST PLUME OF MOISTURE WITH A SUBTROPICAL CONNECTION WITH PRECIPITABLE WATER VALUES OF 1 TO 1.25 INCHES. AIRCRAFT DATA ACROSS THE PACIFIC SHOW A 120-130 KT JET USHERING THIS SYSTEM INTO THE PACIFIC NORTHWEST. THIS SYSTEM WILL ARRIVE LATER TONIGHT AND REMAIN OVER THE NORTHWEST OREGON/SW WASHINGTON THROUGH THURSDAY EVENING. THE MOISTURE LADEN AIR MASS COMBINED WITH STRONG 850 MB WESTERLY FLOW OF 40 TO 50 KTS WILL PRODUCE VERY HEAVY RAINFALL THROUGH THURSDAY EVENING. HEAVIEST RAINFALL WILL BE OVER THE NORTH COAST RANGE AND SW WASHINGTON FOOTHILLS WITH 3 TO 5 INCHES EXPECTED FROM LATE TONIGHT THROUGH THURSDAY EVENING. ELSEWHERE...2 TO 3 INCHES IN THE CASCADES AND 0.75 TO 1.5 INCHES IN THE VALLEYS. HYDRO MODEL RUNS FROM THE NW RIVER FORECAST CENTER SHOW GOOD RISES ON AREA RIVERS...BUT REMAIN BELOW FLOOD STAGE. WILL NEED TO KEEP A VIGILANT WATCH..ESPECIALLY FLASHY RIVERS IN THE COAST RANGE. THE MOIST FRONTAL ZONE MOVES SE THROUGH THE AREA THURSDAY NIGHT AS FLOW TURNS MORE NW AND STARTS SHUTTING DOWN THE MOIST PACIFIC FLOW. BY SECOND HALF OF THURSDAY NIGHT...THE FRONTAL ZONE WEAKENS AND MOVES SOUTH AND EAST OF AREA WITH RESIDUAL SHOWER REMAINING. HIGH PRESSURE BUILDS OVER AREA FRIDAY FOR AN END TO SHOWERS BY AFTERNOON EXCEPT POSSIBLY SOME RESIDUAL LIGHT SHOWERS IN THE CASCADES. HIGH PRESSURE REMAINS OVER THE AREA ON SAT FOR A DRY DAY...THEN MORE WET WEATHER FOR NEXT WEEK IN STORE. TW .LONG TERM...A RIDGE ALOFT OVER THE PACIFIC NORTHWEST WILL SHIFT TO THE EAST SATURDAY NIGHT ALLOWING A SURFACE FRONT TO MOVE IN OFF OF THE PACIFIC. CLOUDS WILL INCREASE AHEAD OF THE FRONT SATURDAY NIGHT WITH LIGHT RAIN MOVING INLAND ON SUNDAY. THE SUPPORTING UPPER LEVEL FLOW WILL SPLIT APART SUNDAY AS A CUTOFF LOW DEVELOPS OFF THE CALIFORNIA COAST. THIS WILL SHEAR THE FRONT APART AND WEAKEN IT VERY RAPIDLY AS IT ATTEMPTS TO MOVE INLAND. THE NORTHERN SECTION OF THE JET STREAM HOWEVER WILL STRENGTHEN AGAIN AS IT DROPS SOUTH TO THE BRITISH COLUMBIA/NORTH WASHINGTON COAST MONDAY AND TUESDAY. THIS WILL ALLOW COUPLE OF STRONGER FRONTS TO MOVE THROUGH THE AREA DURING THE FIRST PART OF NEXT WEEK. COOLER SHOWERY WEATHER WILL FOLLOW AS A COLD UPPER LEVEL TROUGH FROM THE GULF OF ALASKA DIGS DOWN OVER THE PACIFIC NORTHWEST. THIS COOLER AIR MASS WILL BRING SNOW LEVELS IN THE MOUNTAINS DOWN TO 2000 TO 3000 FEET FOR THE SECOND HALF OF NEXT WEEK. RUTHFORD. && .AVIATION...AS EXPECTED COASTAL TERMINALS ALREADY DOWN INTO MVFR AS FIRST CHUNK OF MOISTURE ASSOCIATED WITH A WARM FRONT MOVES THROUGH. NWS DOPPLER RADAR SHOWS A BACK EDGE TO PRECIP NEARING THE COAST AT 22Z SO FLIGHT CONDITIONS MAY IMPROVE FOR A SHORT WHILE. VALLEY TERMINALS GENERALLY LOW VFR WITH SOME POCKETS OF MVFR IN USUAL LOCATIONS SUCH AS KHIO. GFS MODEL STILL SHOWS MORE IMPRESSIVE MOISTURE PLUME REACHING THE COAST 06Z TO 09Z WHICH WILL RESULT IN IFR OR VERY LOW MVFR CONDITIONS THERE THROUGH 00Z FRI. VALLEY SITES WILL BE A TOUGHER CALL...BUT EXPECT PRE-DOMINANT MVFR IN CIGS AND/OR VIS AFTER 08Z OR SO. SOUTH WIND IN THE VALLEY TONIGHT COULD HELP MITIGATE MVFR CONDITIONS AND 850 MB WLY FLOW OF 40-50 KT WILL INDUCE SOME DEGREE OF RAIN-SHADOW OFF THE COAST RANGE. WEISHAAR && .MARINE...WARM FRONT STILL HAS NOT SHOWN AN OBVIOUS PASSAGE NEAR THE COASTLINE YET. SOUTH WIND HAS PICKED UP OVER THE WATERS AS SHOWN IN THE BUOY DATA. BUOY 050 GUSTING TO OR SLIGHTLY ABOVE 30 KT LAST COUPLE HOURS AND CLATSOP SPIT GUSTING 30-35 KT. THEREFORE...HAVE HOISTED GALE WARNING FOR ALL WATERS UPON AFTERNOON FORECAST ISSUANCE. GFS BOUNDARY LAYER WIND PROG VALID 00Z THU SEEMS TO REFLECT ACTUAL CONDITIONS QUITE WELL. WILL KEEP THE GALE GOING THROUGH THURSDAY. NAM-12 HAS 35-40 KT WINDS AT 950 MB WHICH ALSO HELPS SUPPORT GALE WARNING. SEAS WILL BUILD TO 10+ FEET TONIGHT WITH A LARGE WIND-WAVE COMPONENT...THEN EXPECT SEAS TO REMAIN IN THE 11-14 FT RANGE THROUGH FRIDAY. LONGER RANGE LOOKS TO BE A LITTLE MORE ACTIVE THAN THE PAST FEW WEEKS. GFS AND ECMWF BRING A SPLITTING FRONT THROUGH THE WATERS LATE SAT NIGHT WHICH COULD YIELD SMALL CRAFT WIND...FOLLOWED BY STRONGER W-NW FLOW FOR HIGHER CHANCES OF SMALL CRAFT CONDITIONS. WEISHAAR && .OR/WA...GALE WARNING CAPE SHOALWATER TO FLORENCE THROUGH THURSDAY... ...SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR THIS AFTERNOON AND AGAIN TONIGHT THROUGH THURSDAY... && .PRELIMINARY POINT POPS... AST +++21- PDX +++31- SLE +++310 EUG +++310 $$ MORE WEATHER INFORMATION ONLINE AT... http://weather.gov/portland THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
335 AM EST THU FEB 15 2007 .SHORT TERM (TODAY)... WATER VAPOR LOOP SHOWS THE UPPER LEVEL REFLECTION OF THE WINTER STORM IS MOVING OUT OF NEW ENGLAND. AN UPPER LOW IS SLIDING EAST INTO QUEBEC...AS THE NEXT SHORT WAVE DROPS THROUGH THE PLAINS. ACARS 400-250MB WIND OBSERVATIONS SHOW A 175-200KT WESTERLY JET ACROSS THE GULF STATES. 04Z SURFACE ANALYSIS PLACED A 975MB OCCLUDED CYCLONE ALONG THE MAINE COAST. A COLD FRONT EXTENDED WEST THROUGH THE GULF STATES...WITH A 1038MB ANTICYCLONE SPRAWLED ACROSS THE UPPER MIDWEST. MID AND UPPER LEVEL CLOUDS ARE DEVELOPING OVERHEAD ALONG THE UPPER LEVEL JET AXIS. WHILE THE BEST OF THIS MOISTURE SHOULD SHUNT TO THE NORTHEAST THIS MORNING...SOME MID AND UPPER LEVEL CLOUDS ARE EXPECTED TO REMAIN OVERHEAD THROUGH THE AFTERNOON. MEANWHILE...UPSLOPE SNOW SHOWERS WILL DIMINISH TODAY WITH WARM ADVECTION AHEAD OF THE NEXT PAIR OF SHORT WAVES. GRADIENT WILL CONTINUE TO SUPPORT GUSTY WINDS...WITH WIND CHILLS THIS MORNING REMAINING IN THE NEGATIVE 5 TO 10 DEGREE RANGE WHERE THE ADVISORY REMAINS IN EFFECT. DESPITE CONTINUED COLD ADVECTION...TEMPERATURES SHOULD SURPASS 30F (WITH ONLY A SLOW RISE IN THE HIGHER TERRAIN). WIND CHILLS MAY DROP TO SIMILAR LEVELS OVERNIGHT IN THE MOUNTAINS WITH GUSTY WINDS REMAINING ABOVE 2500 FT. DECOUPLING IN THE LOWER TERRAIN WILL ALLOW TEMPERATURES TO DIP THROUGH THE TEENS. ANY REMAINING MID AND UPPER LEVEL MOISTURE ASSOCIATED WITH THE JET AXIS SHOULD BE SHUNTED TO THE SOUTHEAST OVERNIGHT...HOWEVER THE ARRIVAL OF A PAIR OF SHORTWAVES MAY PRODUCE ANOTHER AREA OF MID LEVEL MOISTURE FROM THE WEST. UPSLOPE SNOW SHOWERS ARE EXPECTED TO REDEVELOP AND INTENSIFY DURING THE OVERNIGHT HOURS AS THE SHORT WAVES PASS OVERHEAD. && .LONG TERM... UPSLOPE SNOW SHOWERS WILL COME TO AN END FRIDAY MORNING ALONG AND WEST OF THE ALLEGHENY FRONT. HIGH PRESSURE MOVES ACROSS THE SOUTHEAST CONUS FRIDAY AND FRIDAY NIGHT...ALLOWING COLD NORTHWEST WINDS ON FRIDAY TO SWING AROUND TO THE SOUTHWEST BY SATURDAY. THE NEXT WEATHER MAKER WILL MOVE THROUGH THE OHIO VALLEY ON SATURDAY...AND ACROSS THE MID ATLANTIC SATURDAY NIGHT INTO EARLY SUNDAY. THIS WEAK CLIPPER TYPE SYSTEM WILL BRING A CHANCE OF SNOW SHOWERS. IN THE WAKE OF THE CLIPPER...UPSLOPE SNOW SHOWERS WILL OCCUR OVER THE HIGHLANDS THROUGH THE REST OF THE WEEKEND. ZONAL FLOW DEVELOPS EARLY NEXT WEEK...AND THE MODELS SHOW HEIGHTS AND THICKNESSES RISING TO LEVELS THAT WOULD FAVOR TEMPERATURES CLOSER TO CLIMATOLOGY. && .AVIATION... MID-UPPER LEVEL MOISTURE IS DEVELOPING ALONG THE UPPER LEVEL JET AXIS ACROSS ACROSS CENTRAL VIRGINIA...AND WILL AFFECT THE TERMINALS DURING THE MORNING. GRADIENT WILL SUPPORT WIND GUSTS AROUND 20KTS...ESPECIALLY AFTER DAYBREAK. && .MARINE... 00Z MET/MAV MOS AT THOMAS POINT INDICATE SUSTAINED WINDS DECREASE FROM 20KTS THIS MORNING TO 15 KTS THIS AFTERNOON...AND 12KTS TONIGHT. PROXIMITY NAM/GFS BUFKIT FORECAST SOUNDINGS INDICATE 20-25KT WIND GUST POTENTIAL THROUGH TONIGHT. ICE COVERAGE ACROSS THE EXTREME NORTHERN BAY IS CLOSE TO 7-9 TENTHS. SMALL CRAFT ADVISORY WIND SPEEDS WILL CONTINUE ON FRIDAY...HOWEVER EXCEPT A QUICK REDUCTION IN WIND SPEEDS FRIDAY EVENING WITH DECOUPLING. && .TIDES... CURRENT TIDAL DEPARTURES ARE A FOOT TO A FOOT AND A HALF BELOW ASTRONOMICAL PREDICTIONS...DUE TO A RECENT BLOWOUT. THE LUNAR CYCLE IS WANING TO A NEW MOON (8 PERCENT FULL). THE CHESAPEAKE BAY OPERATIONAL FORECAST SYSTEM AND THE NOAA EXTRATROPICAL STORM SURGE MODEL MAINTAIN CURRENT TIDAL DEPARTURES THROUGH THIS AFTERNOON. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...WIND CHILL ADVISORY UNTIL 9 AM EST THIS MORNING FOR MDZ003>007- 501-502. VA...WIND CHILL ADVISORY UNTIL 9 AM EST THIS MORNING FOR VAZ021-028. WV...WIND CHILL ADVISORY UNTIL 9 AM EST THIS MORNING FOR WVZ050>052- 054-055-501>504. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST FRIDAY FOR ANZ530>534. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR ANZ535>537. SMALL CRAFT ADVISORY FROM 9 AM TO 6 PM EST FRIDAY FOR ANZ535>537. && SHORT TERM/AVIATION/TIDES...ROGOWSKI LONG TERM...PELOQUIN MARINE...ROGOWSKI/PELOQUIN
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
330 AM EST THU FEB 15 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF WITH CLOSED H5 CENTER JUST NE OF LK SUP SANDWICHED BTWN RDG OFF SE CAN AND ANOTHER ONE FM THE ERN PAC EXTENDING NE INTO SW CAN. SLOWLY VEERING 330-350 DEGREE WIND BTWN ARCTIC HI PRES IN THE PLAINS AND LO PRES TO THE E AS SHOWN BY MQT VWP ADVECTING CORE OF COLDEST AIRMASS OVER NRN ONTARIO INTO THE UPR GRT LKS...H85 TEMPS AS LO AS -22C OVER ERN LK SUP PER RUC ANALYSIS. NMRS WIND PARALLEL LES BANDS NOTED ON MQT 88D TO THE E TENDING TO DRIFT SLOWLY W WITH TIME RIGHT NOW AS PATCH OF MID/HI CLD...SHOWN ON IR STLT IMAGERY AND ASSOCIATED WITH SHRTWV OVER ONTARIO ROTATING S ON WRN FLANK OF CLOSED H5 LO...IS DRIFTING ACRS THE FA. SUSPECT SLOWLY SHIFTING WINDS ACCOMPANYING THIS SHRTWV RESPONSIBLE FOR DRIFTING LES BANDS ATTM. 00Z TAMDAR SDNG FM SAW SHOWS HIER RH THRU H7 EXTENDING ABV INVRN ARND H85 ASSOCIATED WITH THIS SHRTWV...AND 00Z INL RAOB/TAMDAR SDNG FM DLH LOOKS SIMILAR. BUT 00Z YPL SDNG ON THE ACYC SIDE OF THIS REINFORCING SHRTWV SHOWS A DRIER MID LVL PROFILE ABOVE A SHARPER/LOWER INVRN ARND H880. SUB INVRN LYR IS ALSO DRIER WITH SFC DWPTS ARND -15F UPSTREAM OF LK SUP. MAIN FCST CONCERNS THIS PACKAGE REVOLVE ARND LES TRENDS/AMTS/ HEADLINES. FOR TDAY...GFS/NAM/CNDN MODELS SHOW SHRTWV ROTATING ARND CLOSED LO MOVING INTO LWR MI BY 00Z FRI. SOME DPVA/H85-5 QVECTOR CNVGC/MID LVL MSTR ASSOCIATED WITH THIS SYS FCST TO LINGER THRU THE MRNG BEFORE GIVING WAY TO DNVA/H85-5 QVECTOR DVGC/MID LVL DRYING IN THE AFTN. 00Z NAM APPEARS TO HAVE BEST HANDLE ON LATEST VEERING WIND TRENDS/ FOCUSED H95 CNVGC/DRIFTING LES BANDS...SO FOLLOWING ITS GUIDANCE MOST CLOSELY FOR FCST TDAY. MODEL SHOWS 340-350 DEGREE WIND WITH FOCUSED LLVL CNVGC OVER CNTRL ALGER/NW SCHOOLCRAFT COUNTIES EARLY THIS MRNG GRDLY BACKING TO 310-320 DEGREES BY 00Z FRI WITH MORE FOCUSED LLVL CNVGC SHIFTING INTO ERN ALGER/NE SCHOOLCRAFT/LUCE COUNTIES IN THE WAKE OF SHRTWV PASSAGE. ALTHOUGH SHIFTING WINDS THIS AFTN WL TEND TO LIMIT RESIDENCE TIME OF BANDS...WL MAINTAIN GOING WRNG FOR ALGER/NRN SCHOOLCRAFT THRU THE DAY. OPTED TO ISSUE LES ADVY FOR LUCE COUNTY BEGINNING MID MRNG AND EXTENDING THRU THE DAY WITH ARRIVAL OF BETTER CNVGC IN THE AFTN. ALTHOUGH SOME MID LVL DRYING WL BE ONGOING THEN...NAM FCST SDNG FOR ERY SHOWS ONLY WEAK INVRN DVLPG ARND 7K FT BY 00Z WITH MOIST PROFILE UP TO THAT LVL. GFS IS A LITTLE FASTER AT SHARPENING INVRN ARND H85...BUT FCST SDNG SHOWS DEEPER MSTR LINGERING THRU H75. LES CHART FOR THESE CONDITIONS WITH TEMPS FVRBL FOR DENDRITIC SN GROWTH AND LK-H85 DELTA T STILL ARND 20C WOULD YIELD UP TO 5"/12 HRS. SHORTER FETCH OVER THE W...EXACERBATED BY RECENT ICE BUILDUP...AS WELL AS SHIFTING WINDS/FASTER ARRIVAL OF MORE ACYC FLOW THIS AFTN WL LIMIT SN ACCUMULATIONS THERE TO THE SUB ADVY RANGE EVEN THOUGH THERE IS SOME FOCUSED CNVGC OVER ONTONAGON COUNTY THIS MRNG IN THE PRESENCE OF DPVA/SOME MID LVL MSTR. A SPOTTER REPORT NEAR ONTONAGON INDICATED ONLY 0.5 INCH FELL THERE THRU 9 PM YDAY EVNG. EXPECT NOTHING MORE THAN -SHSN/FLURRIES OVER THE INLAND CWA AWAY FM LK SUP LLVL MOISTENING. GFS/NAM MOS MAX TEMPS ARE VERY SIMILAR AND APPEAR RSNBL BASED ON MIXING TO INVRN BASE ON GFS FCST SDNGS. AS SHRTWV RDG/SFC RDG AXIS MOVES IN TNGT...EXPECT LINGERING LES TO END LATE OVER THE FAR E WITH CRASHING INVRN HGT BLO 3K FT/ARRIVAL OF MUCH DRIER AIR. LES WL LINGER LONGEST NEAR THE LK SUP SHORELINE E OF GRAND MARAIS. WL MAINTAIN 05Z END FOR WRNGS FOR ALGER/NRN SCHOOLCRAFT BUT KEEP ADVY FOR LUCE COUNTY GOING UNTIL 10Z. OTRW... SKIES WL CLR IN THE EVNG TO THE W BEFORE GFS/NAM INDICATE AN INCRS IN UPR LVL MSTR/HI CLD LATE WITH ISENTROPIC LIFT ON THE 290-300K SFC. ALTHOUGH THE LOWER TROP WL BE QUITE DRY...THE INFLUX OF THIS PACIFIC MSTR ALF AS WELL AS A TIGHTENING PRES GRADIENT/WLY FLOW TO THE N OF THE ARCTIC HI CENTER TRACKING WELL TO THE S WL LIMIT THE DIURNAL DROP IN TEMP. EVEN SO...PREFER THE LOWER NAM/NGM MOS GUIDANCE FOR LO TEMPS AS THERE MAY BE A WINDOW IN THE EVNG FOR TEMPS TO FALL QUICKLY BEFORE THE ARRIVAL OF THE HI CLD/HIER WINDS. NEXT CLIPPER SHRTWV FCST TO DROP SE THRU THE MIDWEST ON FRI...WELL S OF THE FA. HOWEVER...A WEAKER SHRTWV/SFC TROF PROGGED TO MOVE ACRS THE UPR GRT LKS TO THE N OF THE STRONGER FEATURE TO THE S. SOME MODELS GENERATE LGT PCPN (GENERALLY OVER THE W AND N) WHILE OTHERS ARE COMPLETELY DRY. CONSIDERING THE DRY ANTECEDENT AIRMASS IN THE LLVLS...WEAK ISENTROPIC ASCENT...MINIMAL MOS POPS (UNDER 20)...TRACK OF DEEPER LO TO THE S...AND LACK OF JET DYNAMICS/UPR DVGC...OPTED TO MAINTAIN ONLY LO CHC POPS OVER THE W/LK SUP AS IN GOING FCST WITH JUST SOME WEAK DPVA/H85-5 QVECTOR CNVGC AT TIMES DURING THE DAY. PREFER TO TEND TOWARD THE LOWER GFS MOS TEMPS PER MINIMAL ISENTROPIC LIFT AND STABLE LOOK TO FCST SDNGS. EXPECT LES TO DVLP LATER ON FRI NGT/SAT IN THE WAKE OF THIS NRN BRANCH SHRTWV/SFC TROF PASSAGE. GOING CHC -SN FRI NGT COINCIDENT WITH THE PASSAGE OF THIS FEATURE LOOKS ON TRACK AS DOES CHC -SHSN ON SAT IN THE COLD NW FLOW IN THE WAKE OF THE TROF. WL MAINTAIN HIEST POPS IN AREAS FVRD BY FCST NNW FLOW. EXPECT MODERATE LES AMTS IN THE FVRD AREAS...NOT ENUF FOR A HEADLINE ATTM. COORDINATED WITH APX/GRB. && .MQT WATCHES/WARNINGS/ADVISORIES... HEAVY FREEZING SPRAY WARNING FOR LAKE SUPERIOR. LAKE EFFECT SNOW ADVISORY 14Z TDAY THRU 10Z FRI MIZ007. LAKE EFFECT SNOW WARNING THRU 05Z FRI MIZ006-085. && $$ KC
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
915 AM EST THU FEB 15 2007 .SHORT TERM /THIS AFTN/... DOING AN EARLY PCKG TO EXP THE ADVSRY. METEOROLOGICALLY TDA A NICE RESPITE AFTR THE PAST FEW. HV TAKEN DOWN WIND CHILL ADVSRY. SNSH HV TAPERED OFF IN THE WRN HIGHLANDS. BRZY AND COOL THIS AFTN. WOODY! && .PREV DISCUSSION... /ISSUED 335 AM EST THU FEB 15 2007/ SHORT TERM (TODAY)... WATER VAPOR LOOP SHOWS THE UPPER LEVEL REFLECTION OF THE WINTER STORM IS MOVING OUT OF NEW ENGLAND. AN UPPER LOW IS SLIDING EAST INTO QUEBEC...AS THE NEXT SHORT WAVE DROPS THROUGH THE PLAINS. ACARS 400-250MB WIND OBSERVATIONS SHOW A 175-200KT WESTERLY JET ACROSS THE GULF STATES. 04Z SURFACE ANALYSIS PLACED A 975MB OCCLUDED CYCLONE ALONG THE MAINE COAST. A COLD FRONT EXTENDED WEST THROUGH THE GULF STATES...WITH A 1038MB ANTICYCLONE SPRAWLED ACROSS THE UPPER MIDWEST. MID AND UPPER LEVEL CLOUDS ARE DEVELOPING OVERHEAD ALONG THE UPPER LEVEL JET AXIS. WHILE THE BEST OF THIS MOISTURE SHOULD SHUNT TO THE NORTHEAST THIS MORNING...SOME MID AND UPPER LEVEL CLOUDS ARE EXPECTED TO REMAIN OVERHEAD THROUGH THE AFTERNOON. MEANWHILE...UPSLOPE SNOW SHOWERS WILL DIMINISH TODAY WITH WARM ADVECTION AHEAD OF THE NEXT PAIR OF SHORT WAVES. GRADIENT WILL CONTINUE TO SUPPORT GUSTY WINDS...WITH WIND CHILLS THIS MORNING REMAINING IN THE NEGATIVE 5 TO 10 DEGREE RANGE WHERE THE ADVISORY REMAINS IN EFFECT. DESPITE CONTINUED COLD ADVECTION...TEMPERATURES SHOULD SURPASS 30F (WITH ONLY A SLOW RISE IN THE HIGHER TERRAIN). WIND CHILLS MAY DROP TO SIMILAR LEVELS OVERNIGHT IN THE MOUNTAINS WITH GUSTY WINDS REMAINING ABOVE 2500 FT. DECOUPLING IN THE LOWER TERRAIN WILL ALLOW TEMPERATURES TO DIP THROUGH THE TEENS. ANY REMAINING MID AND UPPER LEVEL MOISTURE ASSOCIATED WITH THE JET AXIS SHOULD BE SHUNTED TO THE SOUTHEAST OVERNIGHT...HOWEVER THE ARRIVAL OF A PAIR OF SHORTWAVES MAY PRODUCE ANOTHER AREA OF MID LEVEL MOISTURE FROM THE WEST. UPSLOPE SNOW SHOWERS ARE EXPECTED TO REDEVELOP AND INTENSIFY DURING THE OVERNIGHT HOURS AS THE SHORT WAVES PASS OVERHEAD. LONG TERM... UPSLOPE SNOW SHOWERS WILL COME TO AN END FRIDAY MORNING ALONG AND WEST OF THE ALLEGHENY FRONT. HIGH PRESSURE MOVES ACROSS THE SOUTHEAST CONUS FRIDAY AND FRIDAY NIGHT...ALLOWING COLD NORTHWEST WINDS ON FRIDAY TO SWING AROUND TO THE SOUTHWEST BY SATURDAY. THE NEXT WEATHER MAKER WILL MOVE THROUGH THE OHIO VALLEY ON SATURDAY...AND ACROSS THE MID ATLANTIC SATURDAY NIGHT INTO EARLY SUNDAY. THIS WEAK CLIPPER TYPE SYSTEM WILL BRING A CHANCE OF SNOW SHOWERS. IN THE WAKE OF THE CLIPPER...UPSLOPE SNOW SHOWERS WILL OCCUR OVER THE HIGHLANDS THROUGH THE REST OF THE WEEKEND. ZONAL FLOW DEVELOPS EARLY NEXT WEEK...AND THE MODELS SHOW HEIGHTS AND THICKNESSES RISING TO LEVELS THAT WOULD FAVOR TEMPERATURES CLOSER TO CLIMATOLOGY. AVIATION... VFR CONDS TDA. GRADIENT WILL SUPPORT WIND GUSTS AROUND 20KTS. MARINE... PROXIMITY NAM/GFS BUFKIT FORECAST SOUNDINGS INDICATE 20-25KT WIND GUST POTENTIAL THROUGH TONIGHT. ICE COVERAGE ACROSS THE EXTREME NORTHERN BAY IS CLOSE TO 7-9 TENTHS. SMALL CRAFT ADVISORY WIND SPEEDS WILL CONTINUE ON FRIDAY...HOWEVER EXCEPT A QUICK REDUCTION IN WIND SPEEDS FRIDAY EVENING WITH DECOUPLING. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST FRIDAY FOR ANZ530>534. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR ANZ535>537. SMALL CRAFT ADVISORY FROM 9 AM TO 6 PM EST FRIDAY FOR ANZ535>537. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1054 AM EST THU FEB 15 2007 .UPDATE...DEEP LAYER NORTH/NORTHWEST FLOW IN PLACE ACROSS THE WESTERN GREAT LAKES THIS MORNING...ON THE BACKSIDE OF STORM SYSTEM WHICH IMPACTED THE NORTHEAST ON WEDNESDAY. NORTHWEST FLOW LAKE SNOW BANDS COMING IN OFF LAKE MICHIGAN AFFECTING AREAS WEST OF I-75...LES BANDS OFF LAKE SUPERIOR STILL WEST OF CHIPPEWA COUNTY BUT IMPACTING WESTERN PORTIONS OF MACKINAC COUNTY. SOME DISORGANIZED CONVECTIVE ELEMENTS DRIFTING INTO WHITEFISH BAY... PROBABLY ASSOCIATED WITH LAND BREEZE CONVERGENCE OR SOME RESIDUAL EFFECTS OF LAND BREEZE GIVEN SOUTHWEST WIND AT ERY AND SOUTH/ SOUTHEAST WIND AT WHITEFISH POINT AND POINT IROQUOIS IMPLYING A MESOLOW OR SMALL SCALE TROUGH IN THAT VICINITY. SNOW BANDS ON NORTHERN LAKE HURON JUST CLIPPING AREAS AROUND PRESQUE ISLE. SOME COLDER CLOUDS TOPS EAST OF LAKE SUPERIOR GENERATING SOME LIGHT SNOW/FLURRIES ASSOCIATED WITH WARM ADVECTION/ISENTROPIC ASCENT AND VORTICITY LOBE EXTENDING NORTH/SOUTH ACROSS EASTERN ONTARIO. SOME OF THIS CLOUD COVER AND LIGHT SNOW GRAZING THE EASTERN END OF THE UPPER PENINSULA. 12Z APX SOUNDING PLACED INVERSION HEIGHT AROUND 800MB...850MB TEMPERATURE A BALMY -22C...LOW LEVEL FLOW HAS BECOME PREDOMINANTLY NORTHWEST (AROUND 310 DEGREES THROUGH 6K FEET PER KAPX VWP). AIRCRAFT SOUNDING OUT OF MQT SUGGESTS INVERSION HEIGHTS OFF LAKE SUPERIOR CLOSER TO 850MB. FOCUS FOR THE AFTERNOON WILL BE ON ONGOING LAKE EFFECT. ON LAKE SUPERIOR...APPEARS FLOW HAS SETTLED INTO THE 310-320 DEGREE RANGE WITH LITTLE CHANGE ANTICIPATED THROUGH THE AFTERNOON IN MEAN WIND DIRECTION OR INVERSION HEIGHT. SO POTENTIAL FOR SEVERAL INCHES OF SNOW THROUGH THE AFTERNOON ACROSS WESTERN CHIPPEWA COUNTY THOUGH BETTER SNOW BANDS ANOTHER HOUR OR TWO OFF. ALTHOUGH HASN`T SNOWED MUCH THUS FAR SINCE DAYBREAK...WILL LET THE ADVISORY RIDE AS THERE WILL PROBABLY BE SOME LOCALLY INTENSE SQUALLS THIS AFTERNOON. ON LAKE MICHIGAN...WINDS WILL BE A BIT MORE SHIFTY...ALREADY STARTING TO BACK TOWARD 290 OUT OVER LAKE MICHIGAN PER VISIBLE IMAGERY TRENDS. NO BIG CHANGES IN OVERALL LES PARAMETERS...850MB TEMPERATURES MODERATE A COUPLE DEGREES TODAY...BUT BACKING WINDS REDUCE EFFECTIVE FETCH OFF LAKE SUPERIOR...LONGEST EFFECTIVE FETCH WILL BE ACROSS FAR NORTHERN LAKE MICHIGAN WHERE THE ICE COVER IS GREATEST. THINK FOR THE AFTERNOON HOURS A GENERAL 1-3 INCHES POSSIBLE ACROSS FAVORED 290 FLOW AREAS...WILL KEEP THE CURRENT ADVISORY UP FOR ALL COUNTIES EXCEPT OTSEGO/CRAWFORD WHERE IT WAS SUNNY MUCH OF THE MORNING AND FINALLY STARTING TO SEE SOME LIGHT SNOWFALL. ANTICIPATE CLOUD COVER AND FLURRIES OR LIGHT SNOW SHOWERS TO SPREAD INLAND TODAY WITH THE DIURNAL HEATING CYCLE. SO MUCH OF NORTHEAST LOWER EXPECTED TO CLOUD UP AS THE AFTERNOON WEARS ON. JPB && .PREV DISCUSSION... /ISSUED 340 AM EST THU FEB 15 2007/ DEEP 500 MB LOW REMAINS CENTERED OVER SE ONTARIO EARLY THIS MORNING...WITH A BROAD SURFACE TROUGH EXTENDING FROM THE GREAT LAKES INTO NEW ENGLAND. LAKE EFFECT SNOW SHOWERS CONTINUE TO DEVELOP ACROSS LAKES SUPERIOR...MICHIGAN AND HURON UNDER THE DIRECTION OF NW FLOW. LOW LEVEL FLOW HAS TEMPORARILY SHIFTED NORTH ACROSS ERN LAKE SUPERIOR AND ERN UPPER MICHIGAN (ACTUALLY MORE N/NE FOR FAR ERN UPR MICHIGAN) IN RESPONSE TO A SHORT WAVE DIVING SOUTHWARD THRU CENTRAL UPPER MICHIGAN....HOLDING ALL SNOW SHOWER ACTIVITY WELL WEST OF I 75 ATTM. LOW LEVEL FLOW REMAINS FROM THE NW ACROSS NRN LAKE MICHIGAN AND NRN LAKE HURON...DIRECTING THE MOST PERSISTENT AND HIGHEST INTENSITY SNOW SHOWERS INTO THE TYPICAL SNOWBELT REGIONS OF NW/N CENTRAL LOWER MICHIGAN...WITH ANOTHER BAND WAVING ALONG THE LAKE HURON SHORELINE OF PRESQUE ISLE COUNTY. POTENTIAL FOR ADDITIONAL SNOW ACCUMULATION WITHIN THE ABOVE OUTLINED AREAS WILL REMAIN THE PRIMARY FORECAST ISSUE FOR THE NEXT 24 HOURS. RAPID WARMING AND A TEMPORARY BREAK IN SNOWFALL IS EXPECTED FOR FRIDAY BEFORE OUR NEXT CHANCE OF SNOW ARRIVES FRIDAY NIGHT AND OVER THE WEEKEND. TODAY AND TONIGHT...SHORT WAVE WILL SLOWLY DROP THRU LOWER MICHIGAN TODAY AND THIS EVENING. DELTA T`S WILL REMAIN AROUND 20 DEGREES THRU THIS EVENING AS 900-700 MB RH HOLDS AROUND 85 TO 90 PCT. INVERSION HEIGHTS WILL STAY AROUND 7 KFT THRU THIS EVENING AS WELL...WITH LITTLE CHANGE IN OVERALL LOW LEVEL NW WIND TRAJECTORIES. ONCE SHORT WAVE DROPS SOUTH INTO WISCONSIN AND LOWER MICHIGAN...LOW LEVEL WINDS SHOULD SHIFT BACK TO THE NW ACROSS ERN LAKE SUPERIOR AND ERN UPR MICHIGAN...REDIRECTING LAKE BANDS FURTHER EAST INTO CHIPPEWA COUNTY. SNOWBELT REGIONS OF NW/N CENTRAL LOWER MICHIGAN WILL CONTINUE TO RECEIVE THE MOST PERSISTENT AND HEAVIEST SNOWFALL THRU THIS EVENING. MINOR SHIFTS (UP TO 20 DEGREES) IN THE WIND THROUGHOUT THE DAY WILL ALLOW SNOW SHOWERS TO WAVE BACK AND FORTH ACROSS THIS SNOWBELT REGION... RESULTING IN A WIDER AREA OF SNOWFALL AND SLIGHTLY LESSER AMOUNTS IN ANY GIVEN LOCATION. WILL NEED TO SHIFT THE ADVISORY COUNTIES FURTHER INTO NW FLOW AREAS (I.E. CHARLEVOIX...OTSEGO AND CRAWFORD COUNTIES)...AND WILL DELETE BOTH BENZIE AND MANISTEE FROM THE ADVISORY BASED ON LATEST TRENDS AND THE EXPECTATION THAT LOW LEVEL FLOW WILL REMAIN OUT OF THE NW. IN COORDINATION WITH MQT... WILL ISSUE A LAKE EFFECT SNOW ADVISORY FOR ERN UPR MICHIGAN AS WELL. EXPECT 3-4 INCHES OF NEW SNOW FOR THE ADVISORY AREAS TODAY. SNOWFALL WILL CONTINUE INTO TONIGHT...BUT WILL BEGIN TO DIMINISH OVERNIGHT AS 850 MB TEMPS WARM TO AROUND -11C...900-700 MB RH DECREASES TO AROUND 30 PCT AND INVERSION HEIGHTS DROP TO BELOW 3 KFT BY 12Z SATURDAY. FRIDAY AND FRIDAY NIGHT...A FEW LIGHT SNOW SHOWERS MAY LINGER INTO FRIDAY MORNING AS DELTA T`S OF AROUND 10-11 C LINGER INTO EARLY FRIDAY. LOW LEVEL FLOW WILL BECOME WEST DURING THE DAY AND THEN SW AT NIGHT AS THE SURFACE RIDGE AXIS MOVES OVERHEAD DURING THE DAY AND THEN SHIFTS EAST OF THE REGION FRIDAY NIGHT. FRIDAY AFTERNOON SHOULD BE DRY...PARTLY SUNNY AND WARMER WITH HIGH TEMPS WARMING BACK INTO THE MID 20S. OUR NEXT CHANCE OF SNOW WILL ARRIVE FRIDAY NIGHT (ESPECIALLY OVERNIGHT) AS THE NEXT LOW PRESSURE SYSTEM MOVES INTO THE WRN GREAT LAKES REGION. SUFFICIENT LOW/MID LEVEL COOLING WILL OCCUR FRIDAY NIGHT TO BOTH STEEPEN LAPSE RATES AND TO ONCE AGAIN INVOLVE THE LAKES IN THE GENERATION OF SNOWFALL. WILL MAKE SOME SLIGHT INCREASES TO POPS ACROSS WRN SECTIONS OF THE CWA FOR FRIDAY NIGHT. LOW TEMPS FRIDAY NIGHT WILL DROP BACK INTO THE SINGLE DIGITS AND LOWER TEENS. SATURDAY AND SATURDAY NIGHT...WEAK SHORTWAVE AND ASSOCIATED COLD FRONT CROSS THE CWA DURING THE MORNING HOURS...WITH LOW LEVEL WINDS SHIFTING TO THE NW IN ITS WAKE. MARGINAL DELTA T/S TO START OUT THE DAY INCREASE TO THE NEGATIVE MID TEENS BY EVENING...AND NEGATIVE UPPER TEENS TO LOW 20S OVERNIGHT AS AN ARCTIC STREAM SHORTWAVE DROPS SOUTH AND REINFORCES THE COLD AIR OVER THE GREAT LAKES. INVERSION HEIGHTS GET A BOOST FROM THIS SECONDARY SHORTWAVE AND 900-700MB RH GREATER THAN 65 PCT WILL BE PRESENT THE ENTIRE PERIOD. HAVE SEEN ENOUGH EVIDENCE OVER THE LAST FEW MODEL RUNS TO BUMP UP WORDING TO LIKELY ACROSS THE NW LAKE EFFECT SNOW BELTS FROM SATURDAY AFTERNOON THROUGH SATURDAY NIGHT. SUNDAY AND SUNDAY NIGHT...ONGOING NW FLOW LAKE EFFECT SNOW WILL BE GRADUALLY DIMINISHING WITH INCREASING ANTICYCLONIC FLOW AND SUBSIDENCE...AND LOWERING INVERSION HEIGHTS. WILL MAINTAIN ONGOING CHANCE POPS ON SUNDAY ACROSS THE NW FLOW REGIMES. 850MB TEMPS REMAIN IN THE NEGATIVE MIDDLE TO UPPER TEENS TO START OUT THE NIGHT BUT QUICKLY WARM TO THE NEGATIVE LOWER TO MIDDLE TEENS BY MORNING AS THE SURFACE RIDGE AXIS PASSES ACROSS THE STATE OVERNIGHT. MODELS DEPICT A WARM FRONT ARRIVING BY MORNING AND FUTURE SHIFTS MAY WANT TO CONSIDER ADDING POPS IF THIS FEATURE PERSISTS. MONDAY INTO MONDAY NIGHT...850MB TEMPS WILL CONTINUE TO WARM DUE TO SOUTHWEST WINDS AHEAD OF A BROAD AREA OF LOW PRESSURE OVER THE GREAT PLAINS. TIMING OF FEATURES A LITTLE SKETCHY AT THIS POINT AS THE MODELS CONTINUE TO HAVE A DIFFICULT TIME DEPICTING THE UPCOMING PATTERN CHANGE. NONETHELESS..THE WARMEST AIR IN QUITE SOME TIME DUE TO ARRIVE BY EARLY NEXT WEEK WITH 850MB TEMPS WARMING INTO THE NEGATIVE SINGLE DIGITS. VERY FEW CHANGES MADE DURING THIS PERIOD WITH ONGOING UNCERTAINTY. MPC && .APX WATCHES/WARNINGS/ADVISORIES...LAKE EFFECT SNOW ADVISORY... THIS AFTERNOON...MIZ008-019>021-026-027. && $$
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
200 PM PST THU FEB 15 2007 .SYNOPSIS... HIGH PRESSURE OFF THE CALIFORNIA COAST AND WEAK OFFSHORE FLOW WILL BRING FAIR AND MUCH WARMER WEATHER THROUGH SATURDAY. LOCALLY BREEZY AT TIMES THROUGH SATURDAY...MAINLY THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES. WEAK UPPER LEVEL LOW PRESSURE PASSING BY TO THE SOUTHEAST WILL CAUSE INCREASING CLOUDINESS LATE SATURDAY AND SUNDAY ALONG WITH COOLING SUNDAY. STRONGER LOW PRESSURE FROM THE NORTHWEST WILL BRING MORE CLOUDS AND COOLING WITH A CHANCE OF SHOWERS EARLY NEXT WEEK. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... LATE MORNING ACARS SOUNDING OUT OF KSAN INDICATED THE MARINE LAYER HAD LOWERED TO AROUND 250 FEET SINCE THIS MORNING. WIND DIRECTION AT KSAN SUGGESTS A WEAK EDDY WAS OVER THE COASTAL WATERS AS WELL. RIDGING OVER THE EASTERN PACIFIC IS EXPECTED TO PUSH CLOSER TO THE COAST THROUGH FRIDAY THEN MOVE OVER THE COAST ON SATURDAY. WEAK OFFSHORE FLOW IS EXPECTED TO CONTINUE THROUGH SATURDAY AS WELL. THE COMBINATION OF WEAK OFFSHORE FLOW AND A STRONG RIDGE SHOULD BRING SOME WARMING TO MOST AREAS THROUGH SATURDAY. SOME GUSTY NORTHEAST WINDS ARE EXPECTED THROUGH AND BELOW MOUNTAIN PASSES AND CANYONS BUT WINDS SHOULD REMAIN BELOW WIND ADVISORY LEVELS. ANOTHER TROUGH OF LOW PRESSURE IS EXPECTED TO MOVE CLOSER TO THE COAST ON SUNDAY THEN OVER THE COAST SUNDAY NIGHT INTO MONDAY MORNING. THE LATEST GFS MODELS INDICATE THIS SHORTWAVE SHOULD MOVE THROUGH FAIRLY QUICKLY WITH MOST OF THE SHORTWAVE OUT OF THE AREA BY TUESDAY NIGHT. THIS WOULD SUGGEST THAT MONDAY NIGHT AND TUESDAY SHOULD BE DRYING OUT. WILL LEAVE THIS TO THE NEXT SHIFT TO DECIDE ON SINCE IT IS DURING THE EXTENDED PERIOD. ALSO APPEARS A STRONGER SHORTWAVE WILL MOVE INTO THE AREA LATE IN THE WEEK. && .AVIATION... IT WILL REMAIN CLEAR THROUGH FRIDAY. OFFSHORE FLOW INCREASES FRIDAY MORNING WITH LOCAL GUSTY NE WINDS TO 25 MPH THROUGH PASSES. WINDS AT 5K FT...NORTH TO NORTHEAST 10-15 KT THROUGH FRIDAY AFTERNOON. WINDS AT 10K FT...NORTHEAST 25-35 KT THIS AFTERNOON...THEN NORTHEAST 15-25 KT TONIGHT THROUGH FRIDAY AFTERNOON. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...HORTON AVIATION/MARINE...MACHECKNIE NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
429 PM EST THU FEB 15 2007 .SHORT TERM... TONIGHT AND FRIDAY...HAVE ISSUED A WIND CHILL ADVISORY FOR MUCH OF NORTHERN INDIANA AND NORTHWEST OHIO...EXCEPT FOR AREAS NEAR THE MICHIGAN STATE LINE. THE CORE OF ARCTIC AIR IS EXPECTED TO MOVE ACROSS THE AREA TONIGHT AS SKIES BECOME CLEAR/MOSTLY CLEAR EXCEPT FOR FAR SOUTHERN LOWER MICHIGAN AND BORDERING AREAS TO THE SOUTH. PER ACARS/TAMDAR OBS...NAM/WRF HAS INITIALIZED THE UPSTREAM CORE WELL WITH 925 MB TEMPS BETWEEN -18C AND -19C...WHICH WAS EVEN COLDER THAN THE AIRMASS OVER THE AREA THIS MORNING WHEN FWA...DFI AND GUS DROPPED TO BETWEEN -8F AND -12F. SNOW DEPTHS STILL 8 INCHES TO CLOSE TO 2 FEET OVER THE SOUTHERN HALF OF THE AREA...SOUTH OF HIGHWAY 6...AND SUFFICIENT FOR EVEN RECORD COLD LOWS IF CONDITIONS ARE RIGHT. WINDS SHOULD STAY UP ENOUGH TO CAUSE WIND CHILL TEMPERATURES TO FALL TO BETWEEN -20F AND -25F TONIGHT INTO FRIDAY MORNING. NCEP GFS/MAV AND NGM/FWC MOS NOT HANDLING LOWS VERY WELL...POSTING A LARGE WARM BIAS OF AS MUCH AS 17F. NEEDLESS TO SAY...CUT MOS TEMPS SIGNIFICANTLY. CONDITIONS WILL STILL BE CHILLY FRIDAY MORNING AS RETURN FLOW INCREASES...BUT WARM AIR ADVECTION JUST BEGINNING. && .LONG TERM... FRIDAY NIGHT THROUGH THURSDAY. UPR LVL WEATHER PATTERN OVER THE UNITED STATES AND CANADA WILL UNDERGO A PATTERN SHIFT DURING THE EXTENDED PERIOD. COLD POLAR VORTEX LOCATED OVER SE CANADA AND PREDOMINATE NORTHWEST FLOW WILL GRADUALLY WEAKEN AND SHIFT NORTHWARD BY EARLY NEXT WEEK. IN THE MEANTIME...THERE WILL BE A CLIPPER SYSTEM TO CONTEND WITH IN THE IMMEDIATE LONG TERM PERIOD...AS WELL AS ANOTHER ROUND OF LAKE EFFECT SNOW IN ITS WAKE. PREFER THE 12Z GFS VERSUS THE NAM-WRF IN REGARDS TO THE UPCOMING CLIPPER SYSTEM AND WILL THUS USE CLOSELY. MID LVL S/WV WAS PUSHING ONSHORE ACRS BRITISH COLUMBIA THIS AFTN. THIS FEATURE WILL DIVE RAPIDLY SE INTO THE NRN PLAINS ON FRIDAY...THEN IT WILL HEAD TOWARD THE WRN GREAT LAKES/LOWER OHIO VALLEY FRIDAY NIGHT. DECENT ISENTROPIC LIFT/WAA AHEAD OF THE CLIPPER WILL BRING A SWATH OF SNOW TO THE REGION...BEGINNING FRIDAY EVENING AND CONTINUING INTO SATURDAY MORNING. THERE WILL ALSO BE SOME DYNAMICAL LIFT WITH THE UPR LVL S/WV...AIDING IN UPWARD VERTICAL MOTION. THE MODIFIED GARCIA METHOD AND MODEL QPF INDICATE THAT 2 TO 4 INCHES OF SNOW WILL FALL ACROSS THE REGION FROM FRIDAY NIGHT INTO SATURDAY MORNING. AS THE CLIPPER PASSES TO THE SE BY SATURDAY AFTERNOON...SNOW WILL TAPER OFF. TEMPERATURES FRIDAY NIGHT WILL BE NON DIURNAL AS WAA AND WINDS FROM THE SOUTH/SOUTHWEST ALLOW TEMPS TO RISE SLOWLY TOWARD SATURDAY MORNING. THUS...WILL GO WITH AN EARLY EVENING LOW IN THE MID TEENS WITH TEMPS WARMING TO THE UPPER TEENS TO LOWER 20S BY SATURDAY MORNING. HIGHS ON SATURDAY WILL WARM INTO THE UPPER 20S. FOR SATURDAY NIGHT INTO SUNDAY NIGHT...ONE MORE S/WV WILL DIVE SE OUT OF CENTRAL CANADA INTO THE GREAT LAKES REGION. THIS FEATURE WILL BRING A BRIEF REINFORCING SHOT OF ARCTIC AIR. THE COLD AIR MOVING ACRS THE RELATIVELY WARMER WATERS OF LAKE MICHIGAN WILL GENERATE LAKE EFFECT SNOW SHOWERS. CURRENT FORECAST FETCH OF 300 TO 320 IS EXPECTED. HAVE MAINTAINED CURRENT HIGH CHC POPS IN THE FAVORED LAKE EFFECT COUNTIES FOR SATURDAY NIGHT...AND HAVE EXTENDED THE HIGH CHC INTO SUNDAY. LAKE EFFECT SNOW SHOWERS WILL DIMINISH QUICKLY SUNDAY NIGHT AS A RIDGE OF HIGH PRESSURE BUILDS TOWARD THE REGION. TEMPERATURES WILL REMAIN MUCH BELOW NORMAL DURING THIS PERIOD. AS STATED BEFORE...A PATTERN SHIFT IS IN THE OFFING FOR NEXT WEEK. S/WV ACTIVITY WILL COME ONSHORE ACRS THE WEST COAST...AND WILL TAKE A SRN TRAJECTORY ACRS THE SRN UNITED STATES. MEANWHILE...SOME S/WV ENERGY IN THE NRN JET STREAM (A SPLIT FLOW PATTERN) WILL PUSH A COLD FRONT THROUGH THE REGION TUESDAY/TUESDAY NIGHT. MODELS HAVE BEEN INCONSISTENT WITH THE SRN STREAM S/WV ENERGY...OSCILLATING ITS POSITION FROM RUN TO RUN. THE PATTERN THIS WINTER HAS BEEN TO TAKE THESE SRN STREAM S/WVS END FARTHER NORTH THAN FORECAST. MUCH UNCERTAINTY AT THIS POINT...SO WILL WAIT TO SEE HOW THIS ONE PANS OUT. IN THE MEANTIME...WILL JUST FOCUS ON THE NRN STREAM S/WV AND ASSOCD COLD FRONT TUESDAY/TUESDAY NIGHT. PCPN TYPE WILL BE A CONCERN AS TEMPS WILL WARM TO SLIGHTLY ABOVE FREEZING. WILL GO WITH A CHC OF RAIN OR SNOW ON TUESDAY...WITH A CHC OF SNOW TUESDAY NIGHT IN THE WAKE OF THE FRONT. HIGH PRESSURE IS FCST SETTLE ACRS THE FCST REGION WEDNESDAY AND THURSDAY. WILL FCST PARTLY CLOUDY SKIES WITH TEMPS AT OR SLIGHTLY ABOVE NORMAL. && .AVIATION... LAKE EFFECT SNOW SHOWERS SHOULD TRANSLATE EAST OF SBN THIS AFTERNOON...LEAVING MAINLY CLEAR TO PARTLY CLOUDY SKIES AS HIGH PRESSURE BUILDS INTO THE AREA. CONDITIONS SHOULD BECOME VFR. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL ADVISORY FROM 10 PM EST /9 PM CST/ THIS EVENING TO 11 AM EST /10 AM CST/ FRIDAY FOR INZ008-009-012>018-020- 022>027-032>034. MI...NONE. OH...WIND CHILL ADVISORY FROM 10 PM THIS EVENING TO 11 AM EST FRIDAY FOR OHZ004-005-015-016-024-025. LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST FRIDAY FOR LMZ043-046. && $$ SHORT TERM/AVIATION...SKIPPER LONG TERM....HICKMAN
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
230 PM EST THU FEB 15 2007 .SHORT TERM (TONIGHT-FRIDAY)... MAIN FOCUS IN THE SHORT TERM WILL BE OVER THE NEXT 6-9 HOURS. RADAR SHOWING SOMEWHAT WIDESPREAD FLURRY OR -SHSN ACTIVITY DEVELOPING FROM ROUGHLY HOP-SDF-CVG AS OF 18Z. LAPSE RATES ARE VERY STEEP ON LATEST ACARS SOUNDINGS AT SDF (THROUGH THE -15C LEVEL)...BUT LOW LEVELS ARE QUITE DRY. BEST CHANCES FOR -SHSN WILL BE ALONG RELATIVE MAX IN SFC DEWPOINTS...WHICH CURRENTLY STRETCHES FROM WRN KY UP INTO THE SDF-CVG CORRIDOR. GFS LOW LEVEL RH FIELDS PICK UP ON THIS ENHANCED CLOUDINESS AT THE 900/925MB LEVELS...AND TRANSLATE FEATURE SE INTO OUR ERN COUNTIES BY 22-00Z THIS EVENING...AND OUT OF THE CWA SHORTLY THEREAFTER. WILL INCLUDE A "LATE AFTERNOON" PERIOD IN THE ZONES FOR ISLTD -SHSN. NOT EXPECTING ANY ACCUMS OTHER THAN TRACE GIVEN THE RELATIVELY DRY LOW LEVELS. CLOUD COVER TONIGHT WILL PRESENT A CHALLENGE...WITH NAM DEVELOPING WIDESPREAD LOW STRATUS WHILE GFS IS SIGNIFICANTLY DRIER IN THE LOW LEVELS. FEEL THAT NAM IS OVERDEVELOPING LOW STRATUS THIS AFTN OVER THE SNOW FIELDS NORTH OF THE CWA...WHICH IS SEEN IN THE 6-9HR VERIFICATIONS OF THE 12Z RUN...SO WILL SIDE WITH GFS. WILL STILL MAINTAIN AT LEAST 30% CLOUD COVER OVERNIGHT WITH BANDS OF MID/HIGH LEVEL CLOUDS PASSING THROUGH. LOWS TONIGHT WILL BE VERY COLD OVER THE N 1/3 OF THE DISTRICT...MID-UPPER SINGLE DIGITS. WIND CHILLS WILL LIKELY DROP INTO THE -5 TO -10F RANGE BY DAYBREAK...SO WILL HIGHLIGHT THIS IN HAZ WX OUTLOOK SINCE IT IS BORDERLINE ADVISORY CRITERIA. OVER SRN KY...WCI VALUES SHOULD BE WARMER (~ZERO TO 5 ABOVE). SIG WX NIL DURING THE DAYLIGHT HOURS FRIDAY WITH LOW LEVEL FLOW TURNING MORE SOUTHERLY TOWARD LATE AFTN AHEAD OF APPROACHING CLIPPER. SIGNIFICANT THERMAL TROF REMAINS OVER THE CWA...AND EVEN WITH EXPECTED SUNSHINE...TEMPS WILL ONLY BE A FEW DEGREES WARMER THAN TODAY. CS .LONG TERM (FRIDAY NIGHT-THURSDAY)... ...CLIPPER SYSTEM TO BRING A PERIOD OF SNOW TO THE REGION LATE FRIDAY AND SATURDAY... FRIDAY NIGHT THROUGH SUNDAY NIGHT... OVERALL...SHORT TERM MODEL SOLUTIONS ARE COMING INTO SOMEWHAT BETTER AGREEMENT WITH THIS WEEKENDS CLIPPER SYSTEM. 12Z NAM-WRF AND GFS CONTINUE TO SHOW UPPER LEVEL WAVE AND ASSOCIATED SFC LOW TRACKING SOUTHEAST TOWARD THE OHIO VALLEY. THOUGH AS THE SFC LOW GETS HERE...IT WILL BE WEAKENING. GFS AND NAM CONTINUE TO DIFFER ON THE FORECAST TRACK OF THE SYSTEM WITH THE NAM TAKING THE LOW NORTH OF THE RIVER WITH THE GFS A BIT FURTHER SOUTH. THE GFS TIMING IS FASTER THAN THE NAM WHICH WOULD KEEP MUCH OF THE HEAVIEST PRECIPITATION FALLING DURING THE DAY ON SATURDAY. THERMAL PROFILES HAVE TRENDED COLDER OVER THE LAST FEW RUNS AND OVERALL PROFILES SUGGEST SNOW AS THE PREDOMINANT PRECIPITATION. MAIN FORECAST CHALLENGE HERE WHAT WILL BE THE OVERALL TRACK OF THE SYSTEM. SO FAR THIS SEASON...THE NAM HAS OUTPERFORMED THE GFS SOLUTION HANDS DOWN. THE QPF VALUES HAVE BEEN MORE REALISTIC AS WELL AS THE THERMAL PROFILES. THE GFS HAS ALSO TENDED TO BE COLDER AND MORE WET IN TERMS OF QPF. AT THIS TIME...I THINK THE BEST APPROACH WOULD BE TO GO WITH A BLEND OF BOTH MODELS BUT CLOSER TO THE NAM SOLUTION. QPF AMOUNTS THROUGH THE ENTIRE EVENT WILL BE LESS THAN 0.25 INCHES AND WITH EXPECTED WARMTH IN THE PBL DURING THE DAY ON SATURDAY...SNOW RATIOS WILL BE CLOSE TO CLIMO WHICH IS 12:1. SNOW AMOUNTS FROM THE NAM WOULD SUGGEST 1-2 INCHES WHILE THE GFS SUGGESTS 2-4 INCHES. FOR NOW WILL PLAN ON A GENERAL 1-3...BUT MOST LOCATIONS WOULD LIKELY SEE 1-2 INCHES. IF THE SYSTEM TRENDS FURTHER NORTH...LESS SNOW IS LIKELY. TEMPERATURES SATURDAY WILL START OFF COLD WITH OVERNIGHT LOWS IN THE UPPER TEENS TO THE LOWER 20S. STUCK CLOSER THE THE 2M GFS NUMBERS FOR SATURDAY AFTERNOON WITH HIGHS IN THE UPPER 20S TO AROUND 32. AS CLIPPER SYSTEM MOVES EAST...DEEP NORTHWEST FLOW WILL CONTINUE ACROSS THE REGION. WEAK STATIC STABILITY AND LEFT OVER MOISTURE WILL LIKELY PRODUCE SCT SNOW SHOWERS DURING THE DAY ON SUNDAY ACROSS THE NORTHEAST THIRD OF THE FA. FOR THAT REASON HAVE OPTED TO KEEP LOW CHC POPS IN THE FORECAST HERE. TEMPERATURES WILL REMAIN WELL BELOW NORMAL WITH HIGHS IN THE LOW TO MID 20S IN THE NORTH TO THE UPPER 20S IN THE SOUTH. AS HIGH PRESSURE BUILDS IN...SKIES SHOULD CLEAR OUT SUNDAY NIGHT AND TEMPS WILL RAPIDLY COOL. TEMPS MONDAY MORNING WILL BE HIGHLY DEPENDENT ON SNOW COVER. SINCE WE FEEL WE`LL HAVE SOME SNOW ON THE GROUND...LOWS IN THE UPPER SINGLE DIGITS WILL BE POSSIBLE ACROSS THE NORTHEAST SECTIONS WITH MID TEENS ACROSS THE SOUTHWEST. MONDAY THROUGH THURSDAY... EXTENDED MODEL SOLUTIONS CONTINUE TO SHOW A GENERAL MODERATION IN TEMPERATURES OVER THE UPCOMING WEEK. SFC HIGH PRESSURE IS FORECAST TO MOVE EAST OF THE REGION BY LATE MONDAY ALLOWING DEEP SOUTHWESTERLY FLOW TO RETURN TO THE REGION. COMBINATION OF DEEP SW FLOW COMING OFF THE GULF SHOULD RESULT IN SOME SCT LIGHT PRECIPITATION BY TUESDAY. INITIAL PRECIP MAY BE MIXED OR SNOW...BUT WOULD QUICKLY CHANGE TO RAIN AS TEMPS WARM. 00Z GFS ENSEMBLE SOLUTIONS SUPPORT THIS AND CURRENT FCST HAS THIS COVERED WELL. LATEST 12Z GFS HAS TRENDED MORE SOUTHERLY WITH SFC CYCLONE GOING ACROSS THE GULF COAST STATES. THIS IS IN STARK CONTRAST TO THE 06Z GFS RUN. GIVEN THE RATHER POOR RUN TO RUN CONSISTENCY GENERALLY PLAN ON STICKING CLOSE TO THE 00Z GFS ENSEMBLE PACKAGE FOR THIS PERIOD. ENSEMBLE PACKAGE IS A BIT FURTHER NORTH WITH SFC LOW GOING ACROSS THE SOUTHERN STATES. NET RESULT IS A CHANCE OF PRECIPITATION ON WEDNESDAY WITH DRIER CONDITIONS RETURNING BY THU. THERMAL PROFILES SUGGEST PRECIP ON WED WILL BE RAIN AS OVERALL ARCTIC PATTERN LOOSES ITS GRIP ON THE EASTERN THIRD OF THE COUNTRY. -MJ && .AVIATION (18Z TAFS)... PRIMARY CHALLENGE FOR THE TAFS THIS AFTERNOON WILL BE COVERAGE OF LOW STRATUS. RECENT VISIBLE SATELLITE IMAGERY IS SHOWING WIDESPREAD STRATUS (~2-3KFT AGL) DEVELOPING ALONG AND WEST OF A FFT-BWG LINE. THIS WAS CAPTURED WELL IN THE 12Z NAM LOW LEVEL RH FCSTS...WHICH SHOW STATUS DEVELOPING/ADVECTING SE THROUGH LATE AFTERNOON WITHIN PREVAILING NW BOUNDARY LAYER FLOW. RADAR IS SHOWING SOME VERY WEAK RETURNS WITHIN LOW CLOUDS...SO A FEW FLURRIES ARE POSSIBLE BUT NOTHING EXPECTED AT THIS TIME THAT WOULD RESTRICT VSBYS BELOW 7SM. INTO TONIGHT...LAST NAM FCST SOUNDINGS SHOW THAT STRATUS WOULD BUILD DOWN INTO A SUPER LOW CEILING...HOWEVER GFS IS LESS PESSIMISTIC AS IS MOS GUIDANCE. WILL SIDE WITH THE LATER GROUP...BUT MENTION SOME SCT CLOUDS BELOW 1KFT AGL IN THE EVENT THAT THE NAM VERIFIES. CS && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
110 PM EST THU FEB 15 2007 .UPDATE... QUICK EARLY AFTERNOON UPDATE TO ACCOUNT FOR MORE WIDESPREAD FLURRY OR -SHSN ACTIVITY THAN EARLIER EXPECTED. LAPSE RATES ARE VERY STEEP ON LATEST ACARS SOUNDINGS AT SDF (THROUGH THE -15C LEVEL)...BUT LOW LEVELS ARE QUITE DRY. BEST CHANCES FOR -SHSN WILL BE ALONG RELATIVE MAX IN SFC DEWPOINTS...WHICH CURRENTLY STRETCHES FROM WRN KY UP INTO THE SDF-CVG CORRIDOR. CS && .SHORT TERM (TODAY AND TONIGHT)... UPPER TROUGH MOVING ESE ACROSS FA TODAY WILL BE ACCOMPANIED BY BKN TO OVC MID LEVEL CLOUDS WITH PERHAPS SOME SCT TO BKN SC UNDERNEATH...BOTH CLEARING OUT TONIGHT. UPSTREAM RADARS FROM KS...MO...AND IA DO SHOW SOME LIGHT RETURNS FROM THIS MID DECK BUT THAT PCPN LOOKS MOSTLY TO BE ALOFT. WITH VERY DRY AIR IN PLACE...DID NOT FEEL THAT IT REALLY IS WORTH MENTIONING ANY CHANCE OF FLURRIES AT THIS TIME. BUT TEMPS SHOULD BE A BIT COOLER TODAY...PARTLY IN RESPONSE TO THE INCREASED CLOUDINESS. FOR TONIGHT MIN TEMPS A FEW DEGS COOLER WITH CLEARING SKIES AND LIGHT WINDS GIVING RISE TO GOOD RADIATIONAL COOLING. SO MIN TEMPS 8 TO 10 DEGS N TO 12 TO 14 DEGS NEAR TN BORDER. --21 .LONG TERM (FRIDAY-WEDNESDAY)... SURFACE HIGH WILL BUILD EAST ACROSS THE GULF COAST STATES AND EXTEND NORTH INTO KENTUCKY ON FRIDAY...PROVIDING A SLIGHT WARM UP FROM THE VERY COLD TEMPERATURES. HIGHS ON FRIDAY WILL BE ABOUT 5 DEGREES WARMER THAN TODAY. HOWEVER NEXT COLD FRONT WILL BE DROPPING SOUTHEAST ACROSS THE UPPER PLAINS AND HEADING TOWARD THE LOWER OHIO VALLEY FRIDAY AND FRIDAY NIGHT. MAIN CHALLENGES THIS FORECAST WILL BE TIMING THE FRONT THROUGH AND WHETHER TEMPERATURES WILL BE WARM ENOUGH FOR ANYTHING BUT SNOW ON SATURDAY. HPC PREFERS ECMWF FOR THIS SYSTEM AND WILL GENERALLY FOLLOW 14/12Z ECMWF FOR TIMING THIS SYSTEM. NAM SEEMS TOO SLOW WHILE HPC POINTS OUT THAT GFS IS A LITTLE DEEP WITH H5 TROUGH ALTHOUGH TIMING OF ONSET OF PRECIPITATION IS SIMILAR TO ECMWF AND UKMET. THIS WILL BRING SNOW INTO INTO CENTRAL KENTUCKY BY MORNING WITH MOST OF SNOWFALL OCCURRING DURING THE MORNING AND EARLY AFTERNOON HOURS. LOOKS LIKE 1 TO 1 1/2 INCHES WEST AND 1 TO 2 INCHES OVER THE EAST. UKMET SOUNDING KEEPS TEMPERATURES COOL ENOUGH FOR SNOW DURING THE DAY SATURDAY EVEN ACROSS THE SOUTH. HOWEVER FORECAST HIGHS MAY ALLOW SOME MELTING AS THE PRECIPITATION FALLS. WILL LEAVE SNOW OR RAIN IN FORECAST IN THE SOUTH FOR NOW. SNOW WILL END ACROSS THE AREA SATURDAY NIGHT WITH DRY WEATHER FOR SUNDAY THROUGH MONDAY. ANOTHER SYSTEM MOVES IN FOR THE MIDDLE OF THE WEEK. HAVE NOT MADE ANY SIGNIFICANT CHANGES FOR THIS SYSTEM. SCHOLZ && .AVIATION (18Z TAFS)... PRIMARY CHALLENGE FOR THE TAFS THIS AFTERNOON WILL BE COVERAGE OF LOW STRATUS. RECENT VISIBLE SATELLITE IMAGERY IS SHOWING WIDESPREAD STRATUS (~2-3KFT AGL) DEVELOPING ALONG AND WEST OF A FFT-BWG LINE. THIS WAS CAPTURED WELL IN THE 12Z NAM LOW LEVEL RH FCSTS...WHICH SHOW STATUS DEVELOPING/ADVECTING SE THROUGH LATE AFTERNOON WITHIN PREVAILING NW BOUNDARY LAYER FLOW. RADAR IS SHOWING SOME VERY WEAK RETURNS WITHIN LOW CLOUDS...SO A FEW FLURRIES ARE POSSIBLE BUT NOTHING EXPECTED AT THIS TIME THAT WOULD RESTRICT VSBYS BELOW 7SM. INTO TONIGHT...LAST NAM FCST SOUNDINGS SHOW THAT STRATUS WOULD BUILD DOWN INTO A SUPER LOW CEILING...HOWEVER GFS IS LESS PESSIMISTIC AS IS MOS GUIDANCE. WILL SIDE WITH THE LATER GROUP...BUT MENTION SOME SCT CLOUDS BELOW 1KFT AGL IN THE EVENT THAT THE NAM VERIFIES. CS && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1155 AM EST THU FEB 15 2007 .UPDATE... ISSUED A LES ADVY FOR SOUTHERN SCHOOLCRAFT AS INTENSE SNOW BAND OFF LK SUPERIOR IS REACHING AS FAR INLAND AS BLANEY PARK PER SPOTTER REPORTS...RADAR...SATELLITE LOOP. RADAR SHOWS THE PRIMARY BAND IS AFFECTING EASTERN ALGER AND NORTHERN SCHOOLCRAFT COUNTIES. HAD REPORT FM SCHOOLCRAFT SHERIFF EARLIER OF 10 INCHES OF SNOW SINCE 8 AM ALONG MID POINT OF M-28 ON SENEY STRETCH. PRETTY IMPRESSIVE. SPOTTERS IN LUCE COUNTY REPORT REPORT SIGNIFICANTLY LESS ACCUMS...ON ORDER OF AN 1-3 INCHES IN LAST 12 HRS. ISOLD BAND OF HEAVY LES SHOULD TRANSLATE EWD INTO WEST LUCE COUNTY BY LATE AFTN AS WINDS IN BLYR ARE BACKING MORE WESTERLY. ELSEWHERE ACROSS THE CWA...IT IS PRETTY QUIET. STILL SEEING SOME MOISTURE STARVED...ICE INHIBITED ...LES OVR KEWEENAW. NOT MUCH IN WAY OF ACCUMS THERE. HOWEVER...VSBY AND SPOTTER REPORT AT KCMX SHOWING VSBY UNDER A MILE DUE TO MAINLY GUSTY WINDS/BLSN. ARE ALSO SEEING AN INCREASE IN WINDS HERE AT NWS MQT WHICH IS ALSO PRODUCING BLSN. STDM4 HAD A COUPLE GUSTS EARLIER TO NEAR GALE. OVERALL...STRONGER WINDS WILL BE THIS AFTN BUT DID ADD BLSN IN FAVORED AREAS OF KEWEENAW. SNOW SHOWERS MAY TRY TO INCREASE THERE BRIEFLY THIS AFTN AS WINDS BECOME MORE WEST...BUT EXTENSIVE ICE COVERAGE OVR WEST LK SUPERIOR WILL CUT DOWN THE EFFECTIVE OVER WATER FETCH EVEN WITH MORE FAVORABLE DIRECTION. TEMPS LOOKED FINE...MADE NO CHANGES THERE. && .DISCUSSION (330 AM EST)... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF WITH CLOSED H5 CENTER JUST NE OF LK SUP SANDWICHED BTWN RDG OFF SE CAN AND ANOTHER ONE FM THE ERN PAC EXTENDING NE INTO SW CAN. SLOWLY VEERING 330-350 DEGREE WIND BTWN ARCTIC HI PRES IN THE PLAINS AND LO PRES TO THE E AS SHOWN BY MQT VWP ADVECTING CORE OF COLDEST AIRMASS OVER NRN ONTARIO INTO THE UPR GRT LKS...H85 TEMPS AS LO AS -22C OVER ERN LK SUP PER RUC ANALYSIS. NMRS WIND PARALLEL LES BANDS NOTED ON MQT 88D TO THE E TENDING TO DRIFT SLOWLY W WITH TIME RIGHT NOW AS PATCH OF MID/HI CLD...SHOWN ON IR STLT IMAGERY AND ASSOCIATED WITH SHRTWV OVER ONTARIO ROTATING S ON WRN FLANK OF CLOSED H5 LO...IS DRIFTING ACRS THE FA. SUSPECT SLOWLY SHIFTING WINDS ACCOMPANYING THIS SHRTWV RESPONSIBLE FOR DRIFTING LES BANDS ATTM. 00Z TAMDAR SDNG FM SAW SHOWS HIER RH THRU H7 EXTENDING ABV INVRN ARND H85 ASSOCIATED WITH THIS SHRTWV...AND 00Z INL RAOB/TAMDAR SDNG FM DLH LOOKS SIMILAR. BUT 00Z YPL SDNG ON THE ACYC SIDE OF THIS REINFORCING SHRTWV SHOWS A DRIER MID LVL PROFILE ABOVE A SHARPER/LOWER INVRN ARND H880. SUB INVRN LYR IS ALSO DRIER WITH SFC DWPTS ARND -15F UPSTREAM OF LK SUP. MAIN FCST CONCERNS THIS PACKAGE REVOLVE ARND LES TRENDS/AMTS/ HEADLINES. FOR TDAY...GFS/NAM/CNDN MODELS SHOW SHRTWV ROTATING ARND CLOSED LO MOVING INTO LWR MI BY 00Z FRI. SOME DPVA/H85-5 QVECTOR CNVGC/MID LVL MSTR ASSOCIATED WITH THIS SYS FCST TO LINGER THRU THE MRNG BEFORE GIVING WAY TO DNVA/H85-5 QVECTOR DVGC/MID LVL DRYING IN THE AFTN. 00Z NAM APPEARS TO HAVE BEST HANDLE ON LATEST VEERING WIND TRENDS/ FOCUSED H95 CNVGC/DRIFTING LES BANDS...SO FOLLOWING ITS GUIDANCE MOST CLOSELY FOR FCST TDAY. MODEL SHOWS 340-350 DEGREE WIND WITH FOCUSED LLVL CNVGC OVER CNTRL ALGER/NW SCHOOLCRAFT COUNTIES EARLY THIS MRNG GRDLY BACKING TO 310-320 DEGREES BY 00Z FRI WITH MORE FOCUSED LLVL CNVGC SHIFTING INTO ERN ALGER/NE SCHOOLCRAFT/LUCE COUNTIES IN THE WAKE OF SHRTWV PASSAGE. ALTHOUGH SHIFTING WINDS THIS AFTN WL TEND TO LIMIT RESIDENCE TIME OF BANDS...WL MAINTAIN GOING WRNG FOR ALGER/NRN SCHOOLCRAFT THRU THE DAY. OPTED TO ISSUE LES ADVY FOR LUCE COUNTY BEGINNING MID MRNG AND EXTENDING THRU THE DAY WITH ARRIVAL OF BETTER CNVGC IN THE AFTN. ALTHOUGH SOME MID LVL DRYING WL BE ONGOING THEN...NAM FCST SDNG FOR ERY SHOWS ONLY WEAK INVRN DVLPG ARND 7K FT BY 00Z WITH MOIST PROFILE UP TO THAT LVL. GFS IS A LITTLE FASTER AT SHARPENING INVRN ARND H85...BUT FCST SDNG SHOWS DEEPER MSTR LINGERING THRU H75. LES CHART FOR THESE CONDITIONS WITH TEMPS FVRBL FOR DENDRITIC SN GROWTH AND LK-H85 DELTA T STILL ARND 20C WOULD YIELD UP TO 5"/12 HRS. SHORTER FETCH OVER THE W...EXACERBATED BY RECENT ICE BUILDUP...AS WELL AS SHIFTING WINDS/FASTER ARRIVAL OF MORE ACYC FLOW THIS AFTN WL LIMIT SN ACCUMULATIONS THERE TO THE SUB ADVY RANGE EVEN THOUGH THERE IS SOME FOCUSED CNVGC OVER ONTONAGON COUNTY THIS MRNG IN THE PRESENCE OF DPVA/SOME MID LVL MSTR. A SPOTTER REPORT NEAR ONTONAGON INDICATED ONLY 0.5 INCH FELL THERE THRU 9 PM YDAY EVNG. EXPECT NOTHING MORE THAN -SHSN/FLURRIES OVER THE INLAND CWA AWAY FM LK SUP LLVL MOISTENING. GFS/NAM MOS MAX TEMPS ARE VERY SIMILAR AND APPEAR RSNBL BASED ON MIXING TO INVRN BASE ON GFS FCST SDNGS. AS SHRTWV RDG/SFC RDG AXIS MOVES IN TNGT...EXPECT LINGERING LES TO END LATE OVER THE FAR E WITH CRASHING INVRN HGT BLO 3K FT/ARRIVAL OF MUCH DRIER AIR. LES WL LINGER LONGEST NEAR THE LK SUP SHORELINE E OF GRAND MARAIS. WL MAINTAIN 05Z END FOR WRNGS FOR ALGER/NRN SCHOOLCRAFT BUT KEEP ADVY FOR LUCE COUNTY GOING UNTIL 10Z. OTRW... SKIES WL CLR IN THE EVNG TO THE W BEFORE GFS/NAM INDICATE AN INCRS IN UPR LVL MSTR/HI CLD LATE WITH ISENTROPIC LIFT ON THE 290-300K SFC. ALTHOUGH THE LOWER TROP WL BE QUITE DRY...THE INFLUX OF THIS PACIFIC MSTR ALF AS WELL AS A TIGHTENING PRES GRADIENT/WLY FLOW TO THE N OF THE ARCTIC HI CENTER TRACKING WELL TO THE S WL LIMIT THE DIURNAL DROP IN TEMP. EVEN SO...PREFER THE LOWER NAM/NGM MOS GUIDANCE FOR LO TEMPS AS THERE MAY BE A WINDOW IN THE EVNG FOR TEMPS TO FALL QUICKLY BEFORE THE ARRIVAL OF THE HI CLD/HIER WINDS. NEXT CLIPPER SHRTWV FCST TO DROP SE THRU THE MIDWEST ON FRI...WELL S OF THE FA. HOWEVER...A WEAKER SHRTWV/SFC TROF PROGGED TO MOVE ACRS THE UPR GRT LKS TO THE N OF THE STRONGER FEATURE TO THE S. SOME MODELS GENERATE LGT PCPN (GENERALLY OVER THE W AND N) WHILE OTHERS ARE COMPLETELY DRY. CONSIDERING THE DRY ANTECEDENT AIRMASS IN THE LLVLS...WEAK ISENTROPIC ASCENT...MINIMAL MOS POPS (UNDER 20)...TRACK OF DEEPER LO TO THE S...AND LACK OF JET DYNAMICS/UPR DVGC...OPTED TO MAINTAIN ONLY LO CHC POPS OVER THE W/LK SUP AS IN GOING FCST WITH JUST SOME WEAK DPVA/H85-5 QVECTOR CNVGC AT TIMES DURING THE DAY. PREFER TO TEND TOWARD THE LOWER GFS MOS TEMPS PER MINIMAL ISENTROPIC LIFT AND STABLE LOOK TO FCST SDNGS. EXPECT LES TO DVLP LATER ON FRI NGT/SAT IN THE WAKE OF THIS NRN BRANCH SHRTWV/SFC TROF PASSAGE. GOING CHC -SN FRI NGT COINCIDENT WITH THE PASSAGE OF THIS FEATURE LOOKS ON TRACK AS DOES CHC -SHSN ON SAT IN THE COLD NW FLOW IN THE WAKE OF THE TROF. WL MAINTAIN HIEST POPS IN AREAS FVRD BY FCST NNW FLOW. EXPECT MODERATE LES AMTS IN THE FVRD AREAS...NOT ENUF FOR A HEADLINE ATTM. COORDINATED WITH APX/GRB. && .MQT WATCHES/WARNINGS/ADVISORIES... HEAVY FREEZING SPRAY WARNING FOR LAKE SUPERIOR. LAKE EFFECT SNOW ADVISORY 14Z TDAY THRU 10Z FRI MIZ007. LAKE EFFECT SNOW WARNING THRU 05Z FRI MIZ006-085. LAKE EFFECT SNOW ADVISORY THROUGH 00Z FRI MIZ014. && $$ UPDATE...JLA PREV DISCUSSION...KC