Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 02/13/07

AREA FORECAST DISCUSSION
NWS MIAMI FL
922 PM EST MON FEB 12 2007 .UPDATE...CURRENT RADAR LOOP SHOWS ALL CONVECTION OVER THE WELL OFFSHORE ATLANTIC WATERS MOVING NE. ONLY PATCHES OF LIGHT RAIN LEFT OVER THE PENINSULA AND GULF. ALTHOUGH THE S/W THAT WAS PRODUCING ALL THIS WEATHER IS STILL ALONG THE SW TIP OF CUBA MOVING NORTHEAST NEAR 20 KNOTS. UPPER AIR SOUNDING SHOWED DRYING IN THE LOWER LEVELS AND A DECREASE OF HELICITY AND LOSS OF CONVECTIVE SUPPORT. THE S/W SHOULD REACH SOUTH FLORIDA MID DAY TUESDAY AND THIS IS EXPECTED TO PULL THE WEAK FRONTAL BOUNDARY CURRENTLY OVER THE STRAITS NORTH OVER THE AREA TO PRODUCE POSSIBLE STRONG THUNDERSTORMS. HAVE ALREADY DRASTICALLY REDUCED THE POPS AND REMOVED THE MENTION OF TSTMS FOR TONIGHT. MAY REDUCE THE POPS A LITTLE MORE SOON. && .PREV DISCUSSION... /ISSUED 344 PM EST MON FEB 12 2007/ ..A FEW STRONG STORMS POSSIBLE MAINLY EXTREME SE COAST AND ADJACENT WATERS TONIGHT... ..POTENTIAL COLD WEATHER EVENT LATE THIS WEEK... DISCUSSION... LATEST SURFACE ANALYSIS CONTINUES TO PLACE SURFACE TROUGH EXTENDING FROM THE YUCATAN PENINSULA ACROSS THE FLORIDA STRAITS JUST SOUTH OF THE KEYS NE ALONG THE GULF STREAM EAST OF THE SE FLORIDA COAST AND WEST OF THE BAHAMAS. AT THE UPPER LEVELS...LATEST AIRCRAFT DATA...GOES HIGH DENSITY WINDS...AND WATER VAPOR LOOP SHOW A NEGATIVELY TILTED S/W TROUGH JUST DUE NORTH NORTHEAST OF THE YUCATAN PENINSULA ACROSS THE CENTRAL GULF OF MEXICO AT THIS TIME WITH PLENTY OF DIVERGENCE TO ITS EAST NORTHEAST ALOFT. HOWEVER...WATER VAPOR LOOP CONTINUES TO SHOW A TREND WHEREBY THE AXIS OF THE S/W IS BECOMING LESS NEGATIVELY TILTED AND ONE WOULD EXPECT UPR LVL DIV TO DECREASE WITH THAT IF THAT TREND CONTINUES. FOR THE TIME BEING HOWEVER, THERE IS STILL ENOUGH TO SUPPORT LARGE SCALE ASCENT FOR CONVECTION...EVEN STRONG CONVECTION LIKE IT IS HAPPENING ACROSS THE KEYS. HOWEVER...WHEN LOOKING AT THE CONVECTIVE PARAMETERS ONE CAN SEE THE LIMITING FACTOR AT THIS TIME CONTINUES TO BE LIMITED CAPE (LESS THAN 1000) WITH TEMP PROFILES THAT LOOK VERY CLOSE TO MOIST ADIABATIC A RESULT OF THE LOW LEVEL MOIST AIR ADVECTION THAT HAS BEEN TAKING PLACE SINCE YESTERDAY AND THE EXTENSIVE CLOUD COVER. THE QUESTION IS WHAT HAPPENS NOW FROM THIS POINT ON. GFS40 HAS NOW COME MORE IN LINE WITH NAM12...RUC...AND LOCAL WRF SOLUTIONS. THIS MEANS TROUGH...WHICH CONTINUES TO BE QUASI STATIONARY ACROSS THE KEYS SHOULD BEGIN A GRADUAL MOVEMENT NORTH TONIGHT AND POSSIBLY BE ACROSS NORTHERN SECTIONS OF CWA POSSIBLY BY TUESDAY MORNING. THE SCENARIO STILL CARRIES PLENTY OF UNCERTAINTY GIVEN THE TREND HAS NOT SHOWN A DEFINITE START. BUT AT LEAST GUIDANCE IS CONVERGING ON THE SOLUTION. ALBEIT WEAKER THERE SHOULD BE PLENTY OF DIVERGENCE ALOFT AHEAD OF THE S/W AS IT MOVES ACROSS THE CWA TONIGHT TO SUPPORT TSTMS. HOWEVER...CAPE CONTINUES TO BE RATHER LIMITED AND IS BEST AS YOU WOULD EXPECT WHERE LOW LEVEL MOISTURE FLUX CONVERGENCE IS BEST WHICH IS ALONG EXTREME SE COAST AND THE ATLANTIC GULF STREAM WATERS. 88D TRENDS SHOWS PCPN SHIELD DRIFTING EVER SO SLOWLY NE ALONG THE BOUNDARY AND I EXPECT THIS TREND TO CONTINUE OVERNIGHT YIELDING BEST CHC OF RAIN ALONG EXTREME SE COAST AND THE ADJACENT COASTAL WATERS. THE BEST POSSIBILITY OF ANY STRONG OR EVEN SEVERE THUNDERSTORM I THINK IS CONFINED AT THIS TIME TO THAT AREA TONIGHT WHERE LOW LEVEL WIND SHEAR PROFILES AS BOUNDARY PUSHES NORTH COULD SUPPORT ROTATING STORMS. IN FACT...LOOKING AT THE W/V LOOP SEQUENCE I THINK THAT IS THE ONLY AREA WHERE THERE IS ENOUGH CAPE FOR THE UPR LVL DIVERGENCE AND ASSOCIATED LARGE SCALE ASCENT TO SUPPORT THIS POSSIBILITY ALSO...ALBEIT REMOTE. SO HAVING SAID THAT...WILL FORECAST SHOWERS WITH A CHC OF TSTMS SE COAST AND THE ADJACENT WATERS WITH RAIN CHC OR LIKELY INTERIOR AND WEST COAST AREAS WHERE MOST PCPN SHOULD CONTINUE TO BE STRATIFORM...ALTHOUGH THERE IS STILL A SLIGHT CHC OF TSTMS IN THOSE AREAS TOO. THIS SOLUTION IS CONSISTENT WITH MOST GUIDANCE NOW. AS THE EVENING EVOLVES WILL CONTINUE TO UPDATE HWO AS THREATS EVOLVE PARTICULARLY IF IT WHERE TO INCREASE BEYOND CURRENT EXPECTATIONS. FOR TOMORROW...UPR LVL S/W CURRENTLY ACROSS NW GULF BEHIND PRIMARY ONE WILL BE MOVING ACROSS THE STATE LATE IN THE DAY AND BEING IN THE WARM SECTOR...THERE WILL BE ANOTHER CHC OF BOTH SHOWERS AND TSTMS. HOWEVER...BEST SHOT AT SEVERE WEATHER AT THIS TIME LOOKS TO BE NORTH OF CWA CLOSER TO THE WARM FRONTAL BOUNDARY. AS THE SECONDARY UPR LVL S/W MOVES THROUGH LATE TOMORROW CHC OF RAIN WILL CONTINUE TO DECREASE WITH FRONT EXPECTED TO MOVES ACROSS SOUTH FLORIDA LATE WEDNESDAY. MODELS ARE ALSO SHOWING SOME ISENTROPIC INDUCED RAIN POSSIBLE THU THROUGH EARLY FRI AS THE HIGH BUILDS IN ACROSS THE AREA. THEN A CANADIAN 1040 HIGH WILL BE DROPPING SOUTH ACROSS THE CENTRAL SECTIONS OF THE CONUS WITH HIGH BUILDING IN ACROSS FL. AT THIS TIME THICKNESS VALUES FOR THE 1000-850 MB LAYER LOOKS LOW ENOUGH TO POTENTIALLY SUPPORT NEAR FREEZING TEMPS IN THE NW INTERIOR PARTICULARLY WITH THE GFS CONTINUING TO SHOW HIGH DROPPING ALL THE WAY OVER THE STATE BY FRIDAY NIGHT. NEEDLESS TO SAY THE UNCERTAINTY OF THIS KIND OF FORECAST IS HIGH AT THIS TIME...BUT THE SYNOPTIC SETTING IS THAT OF A POTENTIAL COLD WEATHER EVENT AND WILL HAVE TO WATCH CLOSELY OVER NEXT FEW DAYS. AVIATION... LOW CEILINGS AND PERIODS OF RAIN WILL MAINLY AFFECT THE EAST COAST TAFS DURING THE EVENING CAUSING AT LEAST MVFR CONDITIONS, HOWEVER PERIODS OF HEAVY RAIN AND PERHAPS EVEN A THUNDERSTORM WILL CAUSE EVEN LOWER CONDITIONS. THESE CONDITIONS WILL BE MORE PREVALENT AT TMB, MIA, AND FLL, BUT THESE LOWER CEILINGS AND VIS CONDITIONS WILL STILL BE POSSIBLE AT PBI AND TO A LESSER EXTENT APF. VCSH/VCTS HAS BEEN LEFT IN ALL SITES THROUGH THE PERIOD SINCE THE AREA WILL NOT LIKELY DRY OUT UNTIL TUESDAY NIGHT/WEDNESDAY MORNING. MARINE... OTHER THAT SCEC WIND CONDITIONS ACROSS PORTIONS OF THE OFFSHORE GULF AND ATLANTIC WATERS TONIGHT NO MAIN CONCERNS UNTIL MIDDLE TO LATE IN THE WEEK WITH NORTHERLY WINDS MOVING IN BEHIND FRONT AND SEAS BUILDING TO POSSIBLY 7 FEET OR HIGHER MAINLY ACROSS THE GULF STREAM. THE MAIN CONCERN WILL BE SHOWERS AND A FEW STORMS TONIGHT ACROSS THE ATLANTIC WATERS WITH ONE OR TWO POSSIBLY STRONG. FIRE WEATHER... NO CONCERNS THROUGH FORECAST PERIOD AT THIS TIME. HYDROLOGY... WITH SUSTAINED PERIODS OF MODERATE RAIN CURRENTLY AFFECTING METRO MIAMI DADE AND PORTIONS OF BROWARD...THERE IS THE POSSIBILITY OF MINOR STREET FLOODING IN POORLY DRAINED AREAS AT THIS TIME. BUT NO MAJOR FLOODING IS ANTICIPATED. HOWEVER...IF HEAVIER SHOWERS OR STORMS WERE TO TRAIN OVER THE SAME AREA ACROSS THE METRO AREAS...THE FLOOD POTENTIAL COULD INCREASE ACROSS THESE AREAS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 68 80 64 81 / 70 50 30 10 FORT LAUDERDALE 70 81 67 82 / 70 40 30 10 MIAMI 68 81 66 83 / 70 30 30 10 NAPLES 65 77 69 77 / 50 40 30 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ LONG TERM...18/GR SHORT TERM/AVIATION...30/KOB
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 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. && $$
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
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...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