Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 01/10/07

.SHORT TERM (MONDAY THROUGH WEDNESDAY)... LATEST SURFACE OBS/MODEL SOLUTIONS INDICATE THAT STRONG OFFSHORE WINDS SHOULD CONTINUE ACROSS VENTURA AND LOS ANGELES COUNTIES THIS MORNING. BY THIS AFTERNOON...THE WINDS SHOULD START TO DIMINISH...BUT STILL WILL LIKELY BE ADVISORY CRITERIA ACROSS THE MOUNTAINS AND SOME VALLEY LOCALES. WILL LET DAY SHIFT MAKE THAT DETERMINATION. FOR TUESDAY... OFFSHORE GRADIENTS AND UPPER SUPPORT WILL BE WEAKER...SO WILL STILL HAVE CANYON WINDS...BUT MUCH WEAKER THAN TODAY. BY WEDNESDAY...THE FLOW WILL TURN ONSHORE AS NEXT SYSTEM STARTS TO DEVELOP.

AS FOR TEMPERATURES...TODAY SHOULD BE WELL ABOVE NORMAL WITH MANY COASTAL AND VALLEY AREAS IN THE LOWER TO MID 80S. ON TUESDAY...THE WEAKER OFFSHORE FLOW SHOULD ALLOW FOR SOME SLIGHT COOLING ACROSS COASTAL AND COASTAL VALLEY AREAS...WHILE INLAND AREAS WILL ACTUALLY WARM UP A COUPLE OF DEGREES. ON WEDNESDAY...TEMPS WILL FALL DRAMATICALLY WITH RETURN OF ONSHORE FLOW AND UPPER TROUGH OVER THE AREA.

.LONG TERM (THURSDAY THROUGH SUNDAY)... FOR THURSDAY AND FRIDAY...MODELS CONTINUE TO ADVERTISE A VERY POTENT INSIDE SLIDER FOR THE AREA. QPF PROGS FROM THE MODELS STILL GENERATE SOME SCATTERED LIGHT PRECIP AMOUNTS. SO...WILL CONTINUE WITH MENTION OF SLIGHT CHANCE POPS FOR THE AREA THURSDAY AND FRIDAY. THIS SYSTEM WILL BRING IN QUITE A SHOT OF COLD AIR. SO...BY THURSDAY NIGHT AND FRIDAY...SNOW LEVELS COULD BE BETWEEN 2000 AND 2500 FEET. SO...IF ANY SHOWERS DO DEVELOP...SOME SNOW COULD BE SEEN ACROSS THE SLO INTERIOR VALLEYS...CUYAMA VALLEY AND ANTELOPE VALLEY. FOR SATURDAY AND SUNDAY...DRY CONDITIONS SHOULD PREVAIL AS THE SLIDER MOVES EAST OF THE AREA.

AS WITH MOST INSIDE SLIDERS...SOME GUSTY NORTHERLY WINDS CAN BE EXPECTED THURSDAY AND FRIDAY. GIVEN THE AMOUNT OF COLD ADVECTION THE WINDS COULD BE SIGNIFICANT. FUTURE SHIFTS WILL HAVE TO MONITOR THE WIND POTENTIAL CLOSELY THE NEXT COUPLE OF DAYS.

&&

.AVIATION...STRONG OFFSHORE FLOW WILL CONTINUE ACROSS THE SOUTHLAND S OF POINT CONCEPTION...AS WELL AS N OF POINT CONCEPTION BUT MUCH WEAKER TO THE NORTH. S OF POINT CONCEPTION...EXPECT STG UDDF AND LLWS ACROSS MANY AIR FIELDS THROUGH THE AFTERNOON...ESPECIALLY KBUR AND KVNY. SOME SPEED SHEAR COULD AFFECT SOME AIRCRAFT NEAR LAX...BUT THE FOCUS SHOULD REMAIN OVER THE MOUNTAINS AND VALLEYS.

KLAX WILL EXPERIENCE NORTHEAST WINDS BETWEEN 6-12 KT IN THE MORNING AND THEN A WEAK SEABREEZE IN THE AFTERNOON. SOME SOME SPEED SHEAR COULD AFFECT AIRCRAFT BELOW 10K FT IN THE MORNING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING (SEE LAXNPWLOX). RED FLAG WARNING (SEE LAXRFWLOX). WIND ADVISORY (SEE LAXNPWLOX). SMALL CRAFT ADVISORY (SEE LAXCWFLOX). MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...THOMPSON AVIATION...RORKE

.SHORT TERM /REST OF TODAY/...

FORECAST WELL IN HAND. MADE A FEW UPDATES TO ACCOUNT FOR CURRENT POSITION OF RAIN SHIELD MOVING OUT AND SKY GRIDS. THE REST IS JUST FINE AND DISCUSSED IN THE SEGMENT BELOW.

&&

.PREV DISCUSSION... /ISSUED 625 AM EST MON JAN 8 2006/

UPDATE... WILL BE UPDATING TO ALLOW THE FLOOD WATCH TO EXPIRE AT 12Z. HOURLY RAINFALL TOTALS OVERNIGHT HAVE BEEN A TENTH OF AN INCH OR LESS ACCORDING TO RADAR/METAR/IFLOWS GAGES. IN ADDITION...WILL REMOVE THUNDER ACROSS LOWER SOUTHERN MARYLAND AS CONVECTIVE ELEMENTS ARE FIRMLY WITHIN THE WARM SECTOR...MOVING TOWARD THE DELMARVA. FINALLY...MAY ADJUST POPS SLIGHTLY FOR RADAR TRENDS...AND INCREASE POPS IN MOUNTAINS FOR SNOW SHOWERS THIS AFTERNOON INTO THE LIKELY CATEGORY.

SHORT TERM (TONIGHT THROUGH TUESDAY)... WATER VAPOR LOOP SHOWS A WAVE MOVING THROUGH EASTERN QUEBEC...WITH A SHARP TROUGH MARCHING EAST ACROSS THE CENTRAL CONUS. ACARS 400-250MB WIND OBSERVATIONS REVEAL THE UPPER LEVEL TROUGH ACROSS THE CENTRAL CONUS...WITH A 140-170KT JET FROM THE BASE OF THE TROUGH IN THE PLAINS NORTHEAST THROUGH THE EASTERN GREAT LAKES AND EAST ACROSS MAINE. 04Z SURFACE ANALYSIS PLACED A 1004MB OCCLUDED CYCLONE OVER LAKE ERIE...WITH THE OCCLUDED/COLD FRONT SOUTH THROUGH THE TENNESSEE VALLEY AND CENTRAL GULF OF MEXICO. THE WARM/STATIONARY BOUNDARY DRAPED EAST/NORTHEAST FROM SOUTHWEST VIRGINIA THROUGH THE CENTRAL DELMARVA. A SECOND COLD FRONT STRETCHED SOUTH FROM A 999MB CYCLONE NORTH OF LAKE SUPERIOR THROUGH THE MIDWEST.

COLLABORATION WITH NEIGHBORING OFFICES TO THE SOUTH AND NORTH HAS YIELDED A CONTINUATION OF THE FLOOD WATCH. ANTICIPATE AN EARLY MORNING UPDATE WITH THE EXPIRATION OF THE WATCH. PLEASE REFER TO THE HYDROLOGY SECTION FOR FURTHER DETAILS.

THE PASSAGE OF THE OCCLUDED BOUNDARY THROUGH MID MORNING WILL PROMOTE GREATER MIXING...AND ALLOW CLOUDS TO BEGIN TO BREAK. GREATEST WIND GUSTS OF THE DAY EXPECTED DURING THE MID TO LATE AFTERNOON WITH THE PASSAGE OF THE TRAILING COLD FRONT. SCATTERED UPSLOPE SNOW SHOWERS SHOULD OCCUR IN THE MOUNTAINS WITH INCREASING WESTERLY FLOW...AS TEMPERATURES IN THE HIGHER TERRAIN FALL. DOWNSLOPE WARMING SHOULD OFFSET INITIAL COLD ADVECTION AND ALLOW TEMPERATURES EAST OF THE MOUNTAINS TO RISE INTO THE 50S.

RIDGING BUILDING INTO THE REGION TONIGHT WILL ENCOURAGE ANTICYCLONIC FLOW...BRINGING AN END TO THE MOUNTAIN SNOW SHOWERS. EXPECT LESS THAN AN INCH IN THE UPSLOPE REGIONS.

A MOSTLY CLEAR TO CLEAR SKY WILL BE THE RULE THROUGH MUCH OF THE OVERNIGHT...UNTIL THE NEXT WAVE EMBEDDED WITHIN NORTHWEST FLOW APPROACHES EARLY TUESDAY MORNING. THE DRYING DEWPOINTS AND SLACKENING FLOW UNDER A MOSTLY CLEAR SKY SHOULD ALLOW TEMPERATURES TO DROP INTO THE 20S OUTSIDE OF DOWNTOWN WASHINGTON AND BALTIMORE.

HYDROLOGY... RAINFALL TOTALS FROM MULTISENSOR PRECIPITATION ESTIMATOR THROUGH 07Z...METAR SITES AND IFLOWS GAGES INDICATE A GENERAL THIRD TO HALF INCH OF RAINFALL THUS FAR...WITH A HALF INCH TO AN INCH ACROSS CENTRAL VIRGINIA AND ALONG THE PENNSYLVANIA BORDER OF NORTH CENTRAL MARYLAND.

THERE COULD BE SOME LOCAL ENHANCEMENT WITHIN CONVECTIVE ACTIVITY NEAR THE WARM FRONT ACROSS LOWER SOUTHERN MARYLAND. THE -5C LEVEL IS NEAR 14KFT INDICATING A FAIRLY DEEP WARM RAIN LAYER WITHIN AN AIRMASS WITH PRECIPITABLE WATER VALUES NEAR 1.65" (NEAR THE HIGHEST OBSERVED IN JANUARY AT KIAD BETWEEN 1960 AND 2005). ALSO...THERE WILL BE A GENERAL INCREASE IN LIGHT TO MODERATE RAINFALL ACROSS THE AREA AS THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET PASSES OVER THE REGION EARLY THIS MORNING. DESPITE THESE FACTORS...WITH FLASH FLOOD GUIDANCE NEAR 2 INCHES FOR THE 1/3/6 HOUR PERIOD...DO NOT EXPECT ANYTHING BUT LOCALIZED FLOOD ISSUES THROUGH THE REMAINDER OF THE WATCH.

EXPECT BACK EDGE OF THE RAIN TO REACH THE BAY BY LATE MORNING AS THE AXIS OF THE UPPER LEVEL JET SHIFTS EAST OVERHEAD.

AVIATION... PASSAGE OF OCCLUDED BOUNDARY EARLY THIS MORNING WILL ALLOW CEILINGS/VISIBILITIES TO IMPROVE AND WESTERLY WINDS TO BEGIN TO GUST. A SECOND COLD FRONTAL PASSAGE DURING THE AFTERNOON WILL BRING FURTHER VEERING AND GREATER WIND GUSTS TO THE REGION. WINDS DECOUPLE THROUGH THE EVENING AS STRATOCU WHICH DEVELOPS DURING MORNING MIXING DISSIPATES DUE TO DRY ADVECTION AND DOWNSLOPE DRYING.

MARINE... 00Z GFS/ETA MOS AT THOMAS POINT BOTH SUGGEST SUSTAINED WINDS WILL INCREASE TO 20KT DURING THE DAY...FALLING TO NEAR 10KT BY TUESDAY MORNING. 00Z NAM PROXIMITY LAND BUFKIT FORECAST SOUNDINGS SUGGEST ADDITIONAL WIND GUST MOMENTUM OF 25-30 KNOTS DURING THE AFTERNOON HOURS...WHILE THE 00Z GFS INDICATES GUSTS BETWEEN 28-33 KNOTS. WILL KEEP A MARGINAL GALE WARNING ON ALL WATERS FOR WIND GUSTS TO 35 KNOTS.

SCA WINDS LIKELY TUE NGT AND WED UNDER COOL NW FLOW REGIME AND WITH STRONG S/W PASSAGE.

TIDES... WATER LEVELS ARE CURRENTLY A QUARTER FOOT ABOVE ASTRONOMIC PREDICTIONS. THE LUNAR CYCLE IS WANING FROM A FULL MOON (80% FULL). BOTH THE CHESAPEAKE BAY OPERATIONAL FORECAST SYSTEM AND NOAA EXTRATROPICAL STORM SURGE MODEL GUIDANCE SHOW TIDAL DEPARTURES RISING TO ABOUT A FOOT AHEAD OF THE FRONTAL PASSAGE THIS MORNING.

LONG TERM...TUESDAY THROUGH SUNDAY...

LAKE MOISTURE IN CONJUNCTION WITH UPPER TROUGH SHOULD GENERATE UPSLOPE SNOW SHOWERS BEGINNING TUESDAY AND CONTINUING INTO WEDNESDAY MORNING. AGREE WITH LATEST HPC SNOW CHARTS INDICATING HIGH-END SNOW ADVISORY CRITERIA OVER THREE PERIODS (TUE-WED)...WITH TOTAL ACCUM AROUND 4 INCHES ALONG THE WESTERN SLOPES OF THE ALLEGANY FRONT. AROUND AN INCH ACCUM POSSIBLE ALONG THE WEST FACING SLOPES EAST OF THE FRONT TO THE BLUE RIDGE...INCLUDING THE SKYLINE DR. REMAINING AREAS E OF THE BLUE RIDGE WILL CONTINUE TO MENTION A CHC OF RA/SN SHOWERS ON TUESDAY AFTERNOON. FOR NOW WILL ISSUE A SPECIAL WX STMT TO HIGHLIGHT THE PTNL FOR ACCUMULATING SNOW...BUT TOO EARLY TO ISSUE THE ADVISORY.

FAIRLY ROBUST RIDGING ENSUES FROM WEDNESDAY THROUGH FRIDAY WITH TEMPS MODERATING BACK TO WELL ABOVE NORMAL READING BY NEXT WEEKEND...WHEN MAX TEMPS INTO THE UPPER 50S TO AROUND 60 WILL BE LIKELY. A CHC OF RAIN SHOWERS SAT AND SUN IN A WARM ADVECTION PRECIP PATTERN...THEN A STRONG COLD FRONT MOVES THROUGH SUN NGT OR MONDAY BRINGING A RETURN TO COOLER TEMPERATURES...THOUGH STILL NO COLD OUTBREAKS ON THE ANYTIME ON THE HORIZON.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO MIDNIGHT EST TONIGHT FOR ANZ530>537.

GALE WARNING UNTIL 5 PM EST THIS AFTERNOON FOR ANZ530>537.

&&

$$

SHORT TERM...STRONG PREV FORECAST...ROGOWSKI/JB

.UPDATE... WILL BE UPDATING TO ALLOW THE FLOOD WATCH TO EXPIRE AT 12Z. HOURLY RAINFALL TOTALS OVERNIGHT HAVE BEEN A TENTH OF AN INCH OR LESS ACCORDING TO RADAR/METAR/IFLOWS GAGES. IN ADDITION...WILL REMOVE THUNDER ACROSS LOWER SOUTHERN MARYLAND AS CONVECTIVE ELEMENTS ARE FIRMLY WITHIN THE WARM SECTOR...MOVING TOWARD THE DELMARVA. FINALLY...MAY ADJUST POPS SLIGHTLY FOR RADAR TRENDS...AND INCREASE POPS IN MOUNTAINS FOR SNOW SHOWERS THIS AFTERNOON INTO THE LIKELY CATEGORY.

&&

.SHORT TERM (TONIGHT THROUGH TUESDAY)... WATER VAPOR LOOP SHOWS A WAVE MOVING THROUGH EASTERN QUEBEC...WITH A SHARP TROUGH MARCHING EAST ACROSS THE CENTRAL CONUS. ACARS 400-250MB WIND OBSERVATIONS REVEAL THE UPPER LEVEL TROUGH ACROSS THE CENTRAL CONUS...WITH A 140-170KT JET FROM THE BASE OF THE TROUGH IN THE PLAINS NORTHEAST THROUGH THE EASTERN GREAT LAKES AND EAST ACROSS MAINE. 04Z SURFACE ANALYSIS PLACED A 1004MB OCCLUDED CYCLONE OVER LAKE ERIE...WITH THE OCCLUDED/COLD FRONT SOUTH THROUGH THE TENNESSEE VALLEY AND CENTRAL GULF OF MEXICO. THE WARM/STATIONARY BOUNDARY DRAPED EAST/NORTHEAST FROM SOUTHWEST VIRGINIA THROUGH THE CENTRAL DELMARVA. A SECOND COLD FRONT STRETCHED SOUTH FROM A 999MB CYCLONE NORTH OF LAKE SUPERIOR THROUGH THE MIDWEST.

COLLABORATION WITH NEIGHBORING OFFICES TO THE SOUTH AND NORTH HAS YIELDED A CONTINUATION OF THE FLOOD WATCH. ANTICIPATE AN EARLY MORNING UPDATE WITH THE EXPIRATION OF THE WATCH. PLEASE REFER TO THE HYDROLOGY SECTION FOR FURTHER DETAILS.

THE PASSAGE OF THE OCCLUDED BOUNDARY THROUGH MID MORNING WILL PROMOTE GREATER MIXING...AND ALLOW CLOUDS TO BEGIN TO BREAK. GREATEST WIND GUSTS OF THE DAY EXPECTED DURING THE MID TO LATE AFTERNOON WITH THE PASSAGE OF THE TRAILING COLD FRONT. SCATTERED UPSLOPE SNOW SHOWERS SHOULD OCCUR IN THE MOUNTAINS WITH INCREASING WESTERLY FLOW...AS TEMPERATURES IN THE HIGHER TERRAIN FALL. DOWNSLOPE WARMING SHOULD OFFSET INITIAL COLD ADVECTION AND ALLOW TEMPERATURES EAST OF THE MOUNTAINS TO RISE INTO THE 50S.

RIDGING BUILDING INTO THE REGION TONIGHT WILL ENCOURAGE ANTICYCLONIC FLOW...BRINGING AN END TO THE MOUNTAIN SNOW SHOWERS. EXPECT LESS THAN AN INCH IN THE UPSLOPE REGIONS.

A MOSTLY CLEAR TO CLEAR SKY WILL BE THE RULE THROUGH MUCH OF THE OVERNIGHT...UNTIL THE NEXT WAVE EMBEDDED WITHIN NORTHWEST FLOW APPROACHES EARLY TUESDAY MORNING. THE DRYING DEWPOINTS AND SLACKENING FLOW UNDER A MOSTLY CLEAR SKY SHOULD ALLOW TEMPERATURES TO DROP INTO THE 20S OUTSIDE OF DOWNTOWN WASHINGTON AND BALTIMORE.

&&

.HYDROLOGY... RAINFALL TOTALS FROM MULTISENSOR PRECIPITATION ESTIMATOR THROUGH 07Z...METAR SITES AND IFLOWS GAGES INDICATE A GENERAL THIRD TO HALF INCH OF RAINFALL THUS FAR...WITH A HALF INCH TO AN INCH ACROSS CENTRAL VIRGINIA AND ALONG THE PENNSYLVANIA BORDER OF NORTH CENTRAL MARYLAND.

THERE COULD BE SOME LOCAL ENHANCEMENT WITHIN CONVECTIVE ACTIVITY NEAR THE WARM FRONT ACROSS LOWER SOUTHERN MARYLAND. THE -5C LEVEL IS NEAR 14KFT INDICATING A FAIRLY DEEP WARM RAIN LAYER WITHIN AN AIRMASS WITH PRECIPITABLE WATER VALUES NEAR 1.65" (NEAR THE HIGHEST OBSERVED IN JANUARY AT KIAD BETWEEN 1960 AND 2005). ALSO...THERE WILL BE A GENERAL INCREASE IN LIGHT TO MODERATE RAINFALL ACROSS THE AREA AS THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET PASSES OVER THE REGION EARLY THIS MORNING. DESPITE THESE FACTORS...WITH FLASH FLOOD GUIDANCE NEAR 2 INCHES FOR THE 1/3/6 HOUR PERIOD...DO NOT EXPECT ANYTHING BUT LOCALIZED FLOOD ISSUES THROUGH THE REMAINDER OF THE WATCH.

EXPECT BACK EDGE OF THE RAIN TO REACH THE BAY BY LATE MORNING AS THE AXIS OF THE UPPER LEVEL JET SHIFTS EAST OVERHEAD.

&&

.AVIATION... PASSAGE OF OCCLUDED BOUNDARY EARLY THIS MORNING WILL ALLOW CEILINGS/VISIBILITIES TO IMPROVE AND WESTERLY WINDS TO BEGIN TO GUST. A SECOND COLD FRONTAL PASSAGE DURING THE AFTERNOON WILL BRING FURTHER VEERING AND GREATER WIND GUSTS TO THE REGION. WINDS DECOUPLE THROUGH THE EVENING AS STRATOCU WHICH DEVELOPS DURING MORNING MIXING DISSIPATES DUE TO DRY ADVECTION AND DOWNSLOPE DRYING.

&&

.MARINE... 00Z GFS/ETA MOS AT THOMAS POINT BOTH SUGGEST SUSTAINED WINDS WILL INCREASE TO 20KT DURING THE DAY...FALLING TO NEAR 10KT BY TUESDAY MORNING. 00Z NAM PROXIMITY LAND BUFKIT FORECAST SOUNDINGS SUGGEST ADDITIONAL WIND GUST MOMENTUM OF 25-30 KNOTS DURING THE AFTERNOON HOURS...WHILE THE 00Z GFS INDICATES GUSTS BETWEEN 28-33 KNOTS. WILL KEEP A MARGINAL GALE WARNING ON ALL WATERS FOR WIND GUSTS TO 35 KNOTS.

SCA WINDS LIKELY TUE NGT AND WED UNDER COOL NW FLOW REGIME AND WITH STRONG S/W PASSAGE.

&&

.TIDES... WATER LEVELS ARE CURRENTLY A QUARTER FOOT ABOVE ASTRONOMIC PREDICTIONS. THE LUNAR CYCLE IS WANING FROM A FULL MOON (80% FULL). BOTH THE CHESAPEAKE BAY OPERATIONAL FORECAST SYSTEM AND NOAA EXTRATROPICAL STORM SURGE MODEL GUIDANCE SHOW TIDAL DEPARTURES RISING TO ABOUT A FOOT AHEAD OF THE FRONTAL PASSAGE THIS MORNING.

&&

.LONG TERM...TUESDAY THROUGH SUNDAY...

LAKE MOISTURE IN CONJUNCTION WITH UPPER TROUGH SHOULD GENERATE UPSLOPE SNOW SHOWERS BEGINNING TUESDAY AND CONTINUING INTO WEDNESDAY MORNING. AGREE WITH LATEST HPC SNOW CHARTS INDICATING HIGH-END SNOW ADVISORY CRITERIA OVER THREE PERIODS (TUE-WED)...WITH TOTAL ACCUM AROUND 4 INCHES ALONG THE WESTERN SLOPES OF THE ALLEGANY FRONT. AROUND AN INCH ACCUM POSSIBLE ALONG THE WEST FACING SLOPES EAST OF THE FRONT TO THE BLUE RIDGE...INCLUDING THE SKYLINE DR. REMAINING AREAS E OF THE BLUE RIDGE WILL CONTINUE TO MENTION A CHC OF RA/SN SHOWERS ON TUESDAY AFTERNOON. FOR NOW WILL ISSUE A SPECIAL WX STMT TO HIGHLIGHT THE PTNL FOR ACCUMULATING SNOW...BUT TOO EARLY TO ISSUE THE ADVISORY.

FAIRLY ROBUST RIDGING ENSUES FROM WEDNESDAY THROUGH FRIDAY WITH TEMPS MODERATING BACK TO WELL ABOVE NORMAL READING BY NEXT WEEKEND...WHEN MAX TEMPS INTO THE UPPER 50S TO AROUND 60 WILL BE LIKELY. A CHC OF RAIN SHOWERS SAT AND SUN IN A WARM ADVECTION PRECIP PATTERN...THEN A STRONG COLD FRONT MOVES THROUGH SUN NGT OR MONDAY BRINGING A RETURN TO COOLER TEMPERATURES...THOUGH STILL NO COLD OUTBREAKS ON THE ANYTIME ON THE HORIZON.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR ANZ530>537. SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO MIDNIGHT EST TONIGHT FOR ANZ530>537. GALE WARNING FROM 10 AM THIS MORNING TO 5 PM EST THIS AFTERNOON FOR ANZ530>537.

&&

$$

UPDATE...ROGOWSKI SHORT TERM/HYDROLOGY/AVIATION/TIDES...ROGOWSKI LONG TERM...BROTHERTON MARINE...ROGOWSKI/BROTHERTON

.SHORT TERM (TONIGHT THROUGH TUESDAY)... WATER VAPOR LOOP SHOWS A WAVE MOVING THROUGH EASTERN QUEBEC...WITH A SHARP TROUGH MARCHING EAST ACROSS THE CENTRAL CONUS. ACARS 400-250MB WIND OBSERVATIONS REVEAL THE UPPER LEVEL TROUGH ACROSS THE CENTRAL CONUS...WITH A 140-170KT JET FROM THE BASE OF THE TROUGH IN THE PLAINS NORTHEAST THROUGH THE EASTERN GREAT LAKES AND EAST ACROSS MAINE. 04Z SURFACE ANALYSIS PLACED A 1004MB OCCLUDED CYCLONE OVER LAKE ERIE...WITH THE OCCLUDED/COLD FRONT SOUTH THROUGH THE TENNESSEE VALLEY AND CENTRAL GULF OF MEXICO. THE WARM/STATIONARY BOUNDARY DRAPED EAST/NORTHEAST FROM SOUTHWEST VIRGINIA THROUGH THE CENTRAL DELMARVA. A SECOND COLD FRONT STRETCHED SOUTH FROM A 999MB CYCLONE NORTH OF LAKE SUPERIOR THROUGH THE MIDWEST.

COLLABORATION WITH NEIGHBORING OFFICES TO THE SOUTH AND NORTH HAS YIELDED A CONTINUATION OF THE FLOOD WATCH. ANTICIPATE AN EARLY MORNING UPDATE WITH THE EXPIRATION OF THE WATCH. PLEASE REFER TO THE HYDROLOGY SECTION FOR FURTHER DETAILS.

THE PASSAGE OF THE OCCLUDED BOUNDARY THROUGH MID MORNING WILL PROMOTE GREATER MIXING...AND ALLOW CLOUDS TO BEGIN TO BREAK. GREATEST WIND GUSTS OF THE DAY EXPECTED DURING THE MID TO LATE AFTERNOON WITH THE PASSAGE OF THE TRAILING COLD FRONT. SCATTERED UPSLOPE SNOW SHOWERS SHOULD OCCUR IN THE MOUNTAINS WITH INCREASING WESTERLY FLOW...AS TEMPERATURES IN THE HIGHER TERRAIN FALL. DOWNSLOPE WARMING SHOULD OFFSET INITIAL COLD ADVECTION AND ALLOW TEMPERATURES EAST OF THE MOUNTAINS TO RISE INTO THE 50S.

RIDGING BUILDING INTO THE REGION TONIGHT WILL ENCOURAGE ANTICYCLONIC FLOW...BRINGING AN END TO THE MOUNTAIN SNOW SHOWERS. EXPECT LESS THAN AN INCH IN THE UPSLOPE REGIONS.

A MOSTLY CLEAR TO CLEAR SKY WILL BE THE RULE THROUGH MUCH OF THE OVERNIGHT...UNTIL THE NEXT WAVE EMBEDDED WITHIN NORTHWEST FLOW APPROACHES EARLY TUESDAY MORNING. THE DRYING DEWPOINTS AND SLACKENING FLOW UNDER A MOSTLY CLEAR SKY SHOULD ALLOW TEMPERATURES TO DROP INTO THE 20S OUTSIDE OF DOWNTOWN WASHINGTON AND BALTIMORE.

&&

.HYDROLOGY... RAINFALL TOTALS FROM MULTISENSOR PRECIPITATION ESTIMATOR THROUGH 07Z...METAR SITES AND IFLOWS GAGES INDICATE A GENERAL THIRD TO HALF INCH OF RAINFALL THUS FAR...WITH A HALF INCH TO AN INCH ACROSS CENTRAL VIRGINIA AND ALONG THE PENNSYLVANIA BORDER OF NORTH CENTRAL MARYLAND.

THERE COULD BE SOME LOCAL ENHANCEMENT WITHIN CONVECTIVE ACTIVITY NEAR THE WARM FRONT ACROSS LOWER SOUTHERN MARYLAND. THE -5C LEVEL IS NEAR 14KFT INDICATING A FAIRLY DEEP WARM RAIN LAYER WITHIN AN AIRMASS WITH PRECIPITABLE WATER VALUES NEAR 1.65" (NEAR THE HIGHEST OBSERVED IN JANUARY AT KIAD BETWEEN 1960 AND 2005). ALSO...THERE WILL BE A GENERAL INCREASE IN LIGHT TO MODERATE RAINFALL ACROSS THE AREA AS THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET PASSES OVER THE REGION EARLY THIS MORNING. DESPITE THESE FACTORS...WITH FLASH FLOOD GUIDANCE NEAR 2 INCHES FOR THE 1/3/6 HOUR PERIOD...DO NOT EXPECT ANYTHING BUT LOCALIZED FLOOD ISSUES THROUGH THE REMAINDER OF THE WATCH.

EXPECT BACK EDGE OF THE RAIN TO REACH THE BAY BY LATE MORNING AS THE AXIS OF THE UPPER LEVEL JET SHIFTS EAST OVERHEAD.

&&

.AVIATION... PASSAGE OF OCCLUDED BOUNDARY EARLY THIS MORNING WILL ALLOW CEILINGS/VISIBILITIES TO IMPROVE AND WESTERLY WINDS TO BEGIN TO GUST. A SECOND COLD FRONTAL PASSAGE DURING THE AFTERNOON WILL BRING FURTHER VEERING AND GREATER WIND GUSTS TO THE REGION. WINDS DECOUPLE THROUGH THE EVENING AS STRATOCU WHICH DEVELOPS DURING MORNING MIXING DISSIPATES DUE TO DRY ADVECTION AND DOWNSLOPE DRYING.

&&

.MARINE... 00Z GFS/ETA MOS AT THOMAS POINT BOTH SUGGEST SUSTAINED WINDS WILL INCREASE TO 20KT DURING THE DAY...FALLING TO NEAR 10KT BY TUESDAY MORNING. 00Z NAM PROXIMITY LAND BUFKIT FORECAST SOUNDINGS SUGGEST ADDITIONAL WIND GUST MOMENTUM OF 25-30 KNOTS DURING THE AFTERNOON HOURS...WHILE THE 00Z GFS INDICATES GUSTS BETWEEN 28-33 KNOTS. WILL KEEP A MARGINAL GALE WARNING ON ALL WATERS FOR WIND GUSTS TO 35 KNOTS.

SCA WINDS LIKELY TUE NGT AND WED UNDER COOL NW FLOW REGIME AND WITH STRONG S/W PASSAGE.

&&

.TIDES... WATER LEVELS ARE CURRENTLY A QUARTER FOOT ABOVE ASTRONOMIC PREDICTIONS. THE LUNAR CYCLE IS WANING FROM A FULL MOON (80% FULL). BOTH THE CHESAPEAKE BAY OPERATIONAL FORECAST SYSTEM AND NOAA EXTRATROPICAL STORM SURGE MODEL GUIDANCE SHOW TIDAL DEPARTURES RISING TO ABOUT A FOOT AHEAD OF THE FRONTAL PASSAGE THIS MORNING.

&&

.LONG TERM...TUESDAY THROUGH SUNDAY...

LAKE MOISTURE IN CONJUNCTION WITH UPPER TROUGH SHOULD GENERATE UPSLOPE SNOW SHOWERS BEGINNING TUESDAY AND CONTINUING INTO WEDNESDAY MORNING. AGREE WITH LATEST HPC SNOW CHARTS INDICATING HIGH-END SNOW ADVISORY CRITERIA OVER THREE PERIODS (TUE-WED)...WITH TOTAL ACCUM AROUND 4 INCHES ALONG THE WESTERN SLOPES OF THE ALLEGANY FRONT. AROUND AN INCH ACCUM POSSIBLE ALONG THE WEST FACING SLOPES EAST OF THE FRONT TO THE BLUE RIDGE...INCLUDING THE SKYLINE DR. REMAINING AREAS E OF THE BLUE RIDGE WILL CONTINUE TO MENTION A CHC OF RA/SN SHOWERS ON TUESDAY AFTERNOON. FOR NOW WILL ISSUE A SPECIAL WX STMT TO HIGHLIGHT THE PTNL FOR ACCUMULATING SNOW...BUT TOO EARLY TO ISSUE THE ADVISORY.

FAIRLY ROBUST RIDGING ENSUES FROM WEDNESDAY THROUGH FRIDAY WITH TEMPS MODERATING BACK TO WELL ABOVE NORMAL READING BY NEXT WEEKEND...WHEN MAX TEMPS INTO THE UPPER 50S TO AROUND 60 WILL BE LIKELY. A CHC OF RAIN SHOWERS SAT AND SUN IN A WARM ADVECTION PRECIP PATTERN...THEN A STRONG COLD FRONT MOVES THROUGH SUN NGT OR MONDAY BRINGING A RETURN TO COOLER TEMPERATURES...THOUGH STILL NO COLD OUTBREAKS ON THE ANYTIME ON THE HORIZON.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...FLOOD WATCH UNTIL 7 AM EST THIS MORNING FOR DCZ001. MD...FLOOD WATCH UNTIL 7 AM EST THIS MORNING FOR MDZ003>007-009>011-013-014-501-502. VA...FLOOD WATCH UNTIL 7 AM EST THIS MORNING FOR VAZ021-025>031- 036>042-050>057. WV...FLOOD WATCH UNTIL 7 AM EST THIS MORNING FOR WVZ050>055-501>504. MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR ANZ530>537. SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO MIDNIGHT EST TONIGHT FOR ANZ530>537. GALE WARNING FROM 10 AM THIS MORNING TO 5 PM EST THIS AFTERNOON FOR ANZ530>537.

&&

$$

SHORT TERM/HYDROLOGY/AVIATION/TIDES...ROGOWSKI LONG TERM...BROTHERTON MARINE...ROGOWSKI/BROTHERTON

.UPDATE...

AREA RADAR DATA HAS SHOWN THE LAKE EFFECT HAS TRANSITIONED TO A TYPICAL NORTHWEST FLOW REGIME WITH MORE NUMEROUS COVERAGE OVER SW LOWER MICHIGAN. MOST OF THE SNOW ACROSS SE MICHIGAN IS IN THE FORM OF SCATTERED TO ISOLATED FLURRIES. THE EXCEPTION IS ACROSS THE THUMB WHERE MOISTURE FLUX OFF SAGINAW BAY IS HELPING TO SUSTAIN A LITTLE HIGHER RETURNS. WILL UPDATE THE FORECAST TO REFLECT THESE CHANGES. SOME BREAKS IN THE CLOUDS THIS EVENING HAS ALLOWED TEMPS TO APPROACH THE FORECAST MINS. THE LAKE EFFECT CLOUDS ARE SLOWLY EXPANDING BACK INTO THE AREA UNDERNEATH A SHARP 800MB INVERSION BASED OFF THE 00Z DTX SOUNDING. THIS ALONG WITH THE GUSTY WEST/NORTHWESTERLY WINDS SHOULD KEEP TEMPS FROM DROPPING MUCH BELOW CURRENT READINGS. IN LIGHT OF CURRENT TEMPS THOUGH...WILL UPDATE THE ZONES/GRIDS AND LOWER FORECAST MINS A COUPLE DEGREES.

&&

.PREV DISCUSSION...ISSUED 623 PM EST TUE JAN 9 2007

AVIATION...

THE PRESSURE GRADIENT WILL MAINTAIN RATHER GUSTY WESTERLY WINDS ACROSS SOUTHERN MICHIGAN THROUGH THE NIGHT. THE WIND SPEEDS WILL STILL DIMINISH A LITTLE BIT THROUGH THE NIGHT THOUGH DUE TO NOCTURNAL COOLING IN THE BOUNDARY LAYER. LATEST TRENDS IN RADAR HAVE SHOWN A GENERAL DIMINISHING TREND TO THE SNOW SHOWERS WITH THE LOSS OF DAYTIME HEATING. THERE HAS EVEN BEEN A NOTICEABLE CLEARING TREND OCCURRING. WEST-NORTHWESTERLY FLOW AND WEAK LOW LEVEL COLD AIR ADVECTION WILL STILL RESULT IN LAKE EFFECT SNOW SHOWERS OFF LAKE MICHIGAN. THE MORE NUMEROUS SNOW SHOWERS HOWEVER SHOULD REMAIN OVER WESTERN LOWER MI. LATEST TAMDAR SOUNDINGS OUT OF DTW SHOWED INVERSION HEIGHTS AROUND 6500FT...WHICH HAS ALLOWED MOST OF THE CLOUDS TO BE IN THE VFR CATEGORY. INVERSIONS ARE FORECAST TO REMAIN AROUND 6K FEET THROUGH THE NIGHT BEFORE FALLING AFTER 12Z AS RIDGING AT THE SURFACE AND ALOFT BUILD INTO THE STATE. DESPITE THE CLEARING TREND...MOISTURE TRAPPED UNDER THE INVERSION WILL LIKELY ALLOW THE VFR STRATO CU FIELD TO EXPAND BACK INTO SE MICHIGAN LATER THIS EVENING.

PREV DISCUSSION...ISSUED 358 PM EST TUE JAN 9 2007

SHORT TERM...TONIGHT AND WEDNESDAY

BROAD SURFACE CYCLONIC FLOW WILL PERSIST OVER THE REGION TONIGHT BEFORE GIVING WAY TO HIGH PRESSURE TOMORROW. A TIGHT PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS WILL REMAIN IN PLACE OVERNIGHT...THUS MAKING FOR A COLD BREEZY NIGHT. COLD AIR...EMBEDDED WITHIN NORTHWEST FLOW ON THE BACK SIDE OF A DEPARTING UPPER TROUGH...WILL CONTINUE TO FILTER INTO THE AREA OVERNIGHT...BEFORE BECOMING MODIFIED TOMORROW. 850 TEMPS ARE FORECAST TO DROP FROM -13C TO -17C THIS EVENING. THIS WILL BE ENOUGH TO KEEP LIGHT LAKE EFFECT SHOWERS/FLURRIES GOING THROUGH THE NIGHT. AVAILABLE MOISTURE REMAINS TO BE THE LIMITING FACTOR. AIRMASS WILL REMAIN QUITE DRY ABOVE 6K FEET AND MOISTURE DEPTH BELOW INVERSION WILL REMAIN RELATIVELY SHALLOW. DEWPOINTS IN THE TEENS NEAR THE SURFACE WILL ALSO CONTINUE TO AID IN RESTRICTING THE INTENSITY OF LAKE EFFECT SNOW. NUMEROUS FLURRIES WILL RESIDE OVER THE AREA THROUGH THE NIGHT...WITH A SMALL POTENTIAL OF SOME SCATTERED ACTIVITY BECOMING A LITTLE STRONGER (VISIBILITIES BRIEFLY 3 TO 5 MILES)...THUS THE REASONING FOR SCATTERED LIGHT SNOW SHOWERS AND 30 POPS. 500 MB VORT MAX WILL MOVE OVERHEAD AFTER MIDNIGHT SO WILL KEEP THIS GOING UNTIL SUNRISE. TEMPS TONIGHT SHOULD DROP DOWN TO AROUND 20 IF NOT THE UPPER TEENS...DESPITE MOSTLY CLOUDY SKIES AND WINDS REMAINING UP. WIND CHILLS AROUND 10 DEGREES CAN BE EXPECTED AROUND SUNRISE.

AN EVEN DRIER AIRMASS WILL WORK IN DURING THE DAY. SHOULD SEE PLENTY OF SUN ON WEDNESDAY AS HIGH PRESSURE BEGINS TO BUILD IN. HOWEVER...ENOUGH COLD AIR WILL BE IN PLACE TO KEEP TEMPS AROUND NORMALS...UPPER 20S TO LOW 30S.

LONG TERM...

WATER VAPOR IMAGERY AND 00Z RAOBS INDICATE A COLD UPPER LOW JUST OFF THE BRITISH COLUMBIA COAST SINKING SOUTH-SOUTHEAST. ALL SHORT TERM MODELS INDICATE THIS DIGGING TROUGH WILL CAPTURE/ABSORB THE SOUTHERN STREAM UPPER WAVE JUST SOUTHWEST OF THE SUB-DRIFTING BUOY A8ES9 IN THE PACIFIC. THIS WARM ORIGIN WAVE IS EXPECTED TO RACE OFF TO THE NORTHEAST IN AN ELONGATED AND WEAKENED FASHION...MOVING THROUGH THE GREAT LAKES REGION ON FRIDAY. GOOD WARM/MOISTURE ADVECTION OVER SOUTHEAST MICHIGAN WITH ISENTROPIC LIFT EXPECTED TO LEAD TO OVERRUNNING PRECIPITATION LATE THURSDAY NIGHT AND FRIDAY. THINKING PRECIPITATION WILL BE MOSTLY/ALL RAIN EVENT DURING/BY FRIDAY. EVEN IF ONE GOES WITH THE COLDER 12Z GFS SOLUTION...BASED ON THE 1000-850 MB THICKNESSES...ONLY THE NORTHERN THUMB AND TRI- CITIES REGION IS HOVERING AROUND 1305 M OR SLIGHTLY COLDER (12Z FRIDAY). THE 12Z UKMET IS INDICATING THICKNESSES A GOOD 15 METERS HIGHER WITH THERMAL RIDGE MOVING IN DURING THE DAY.

THE FORECAST FOR THE WEEKEND THEN BECOMES VERY COMPLICATED AS A TIGHT BAROCLINIC ZONE SETS UP OVER THE GREAT LAKES REGION IN THE WAKE OF FRIDAY`S WAVE. THE DEPTH OF THE COLD AIR MOVING INTO SOUTHERN LOWER MICHIGAN FRIDAY NIGHT AND SATURDAY WILL BE CRITICAL FOR THE POTENTIAL SIGNIFICANT STORM LATE IN THE WEEKEND AS LARGE SURFACE HIGH SLIDES ACROSS EASTERN CANADA.

12Z GFS...GLOBAL CANADIAN...AND EUROPEAN ARE ALL GENERALLY SHOWING THE SAME CONCEPT...WITH THE ALL IMPORTANT DETAILS SIGNIFICANTLY DIFFERENT. LARGE UPPER LOW OVER THE CENTRAL/SOUTHERN ROCKIES ON SATURDAY WITH POLAR VORTEX OVER NORTH CENTRAL CANADA DROPPING SOUTH. THESE TWO SYSTEMS ARE EXPECTED TO PHASE...WITH THE TIMING OF THIS OCCURRENCE AND THE POSITION OF THE PREVIOUSLY MENTIONED BAROCLINIC ZONE DICTATING THE TRACK OF THE SURFACE LOW EJECTING FROM THE PLAINS. THE 12Z EUROPEAN AND GLOBAL CANADIAN ARE THE FARTHEST WEST AND WARMEST...AS THE SURFACE LOW TRACKS THROUGH SOUTHERN LOWER MICHIGAN. IT SHOULD BE NOTED THE CANADIAN IS MUCH SLOWER AND DEEPER. BOTH THESE SOLUTIONS WOULD CALL FOR MOSTLY A RAIN EVENT...WHICH COULD LEAD TO FLOODING WITH THE RIVERS RUNNING HIGH.

THE 12Z GFS IS INDICATING A TRACK THROUGH NORTHERN OHIO/NORTHWEST PENNSYLVANIA...WHICH IS JUST ABOUT THE IDEAL TRACK FOR A MAJOR WINTER EVENT OVER SOUTHEAST MICHIGAN. BASED ON THE 12Z EUROPEAN TRENDING SLIGHTLY FARTHER EAST THAN IT`S 00Z RUN...FELT A COMPROMISED TRACK ALONG OR NEAR THE DETROIT RIVER ON SUNDAY IS THE BEST WAY TO GO AT THIS TIME. THIS TRACK WOULD STILL RESULT IN A WINTRY MESS ACROSS THE NORTH HALF OF THE CWA...WITH MOSTLY RAIN ACROSS THE SOUTH HALF.

ARCTIC AIR WILL THEN SWEEP IN BEHIND THE SYSTEM EARLY NEXT WEEK...WITH LAKE EFFECT SNOW SHOWERS/FLURRIES A GOOD BET. DEPENDING ON THE SNOWPACK...MAX TEMPS COULD BE STUCK IN THE TEENS ON TUESDAY.

&&

.DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...GALE WARNING...SOUTH HALF UNTIL 7 AM WEDNESDAY.

SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING SAGINAW BAY UNTIL 7 AM WEDNESDAY.

LAKE ST CLAIR...SMALL CRAFT ADVISORY...LCZ460 UNTIL 7 AM WEDNESDAY.

MI WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY...UNTIL 7 AM WEDNESDAY.

&&

$$

SHORT TERM...SHULER LONG TERM....SF AVIATION/UPDATE...CONSIDINE

YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

.AVIATION...

THE PRESSURE GRADIENT WILL MAINTAIN RATHER GUSTY WESTERLY WINDS ACROSS SOUTHERN MICHIGAN THROUGH THE NIGHT. THE WIND SPEEDS WILL STILL DIMINISH A LITTLE BIT THROUGH THE NIGHT THOUGH DUE TO NOCTURNAL COOLING IN THE BOUNDARY LAYER. LATEST TRENDS IN RADAR HAVE SHOWN A GENERAL DIMINISHING TREND TO THE SNOW SHOWERS WITH THE LOSS OF DAYTIME HEATING. THERE HAS EVEN BEEN A NOTICEABLE CLEARING TREND OCCURRING. WEST-NORTHWESTERLY FLOW AND WEAK LOW LEVEL COLD AIR ADVECTION WILL STILL RESULT IN LAKE EFFECT SNOW SHOWERS OFF LAKE MICHIGAN. THE MORE NUMEROUS SNOW SHOWERS HOWEVER SHOULD REMAIN OVER WESTERN LOWER MI. LATEST TAMDAR SOUNDINGS OUT OF DTW SHOWED INVERSION HEIGHTS AROUND 6500FT...WHICH HAS ALLOWED MOST OF THE CLOUDS TO BE IN THE VFR CATEGORY. INVERSIONS ARE FORECAST TO REMAIN AROUND 6K FEET THROUGH THE NIGHT BEFORE FALLING AFTER 12Z AS RIDGING AT THE SURFACE AND ALOFT BUILD INTO THE STATE. DESPITE THE CLEARING TREND...MOISTURE TRAPPED UNDER THE INVERSION WILL LIKELY ALLOW THE VFR STRATO CU FIELD TO EXPAND BACK INTO SE MICHIGAN LATER THIS EVENING.

&&

.PREV DISCUSSION...ISSUED 358 PM EST TUE JAN 9 2007

SHORT TERM...TONIGHT AND WEDNESDAY

BROAD SURFACE CYCLONIC FLOW WILL PERSIST OVER THE REGION TONIGHT BEFORE GIVING WAY TO HIGH PRESSURE TOMORROW. A TIGHT PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS WILL REMAIN IN PLACE OVERNIGHT...THUS MAKING FOR A COLD BREEZY NIGHT. COLD AIR...EMBEDDED WITHIN NORTHWEST FLOW ON THE BACK SIDE OF A DEPARTING UPPER TROUGH...WILL CONTINUE TO FILTER INTO THE AREA OVERNIGHT...BEFORE BECOMING MODIFIED TOMORROW. 850 TEMPS ARE FORECAST TO DROP FROM -13C TO -17C THIS EVENING. THIS WILL BE ENOUGH TO KEEP LIGHT LAKE EFFECT SHOWERS/FLURRIES GOING THROUGH THE NIGHT. AVAILABLE MOISTURE REMAINS TO BE THE LIMITING FACTOR. AIRMASS WILL REMAIN QUITE DRY ABOVE 6K FEET AND MOISTURE DEPTH BELOW INVERSION WILL REMAIN RELATIVELY SHALLOW. DEWPOINTS IN THE TEENS NEAR THE SURFACE WILL ALSO CONTINUE TO AID IN RESTRICTING THE INTENSITY OF LAKE EFFECT SNOW. NUMEROUS FLURRIES WILL RESIDE OVER THE AREA THROUGH THE NIGHT...WITH A SMALL POTENTIAL OF SOME SCATTERED ACTIVITY BECOMING A LITTLE STRONGER (VISIBILITIES BRIEFLY 3 TO 5 MILES)...THUS THE REASONING FOR SCATTERED LIGHT SNOW SHOWERS AND 30 POPS. 500 MB VORT MAX WILL MOVE OVERHEAD AFTER MIDNIGHT SO WILL KEEP THIS GOING UNTIL SUNRISE. TEMPS TONIGHT SHOULD DROP DOWN TO AROUND 20 IF NOT THE UPPER TEENS...DESPITE MOSTLY CLOUDY SKIES AND WINDS REMAINING UP. WIND CHILLS AROUND 10 DEGREES CAN BE EXPECTED AROUND SUNRISE.

AN EVEN DRIER AIRMASS WILL WORK IN DURING THE DAY. SHOULD SEE PLENTY OF SUN ON WEDNESDAY AS HIGH PRESSURE BEGINS TO BUILD IN. HOWEVER...ENOUGH COLD AIR WILL BE IN PLACE TO KEEP TEMPS AROUND NORMALS...UPPER 20S TO LOW 30S.

LONG TERM...

WATER VAPOR IMAGERY AND 00Z RAOBS INDICATE A COLD UPPER LOW JUST OFF THE BRITISH COLUMBIA COAST SINKING SOUTH-SOUTHEAST. ALL SHORT TERM MODELS INDICATE THIS DIGGING TROUGH WILL CAPTURE/ABSORB THE SOUTHERN STREAM UPPER WAVE JUST SOUTHWEST OF THE SUB-DRIFTING BUOY A8ES9 IN THE PACIFIC. THIS WARM ORIGIN WAVE IS EXPECTED TO RACE OFF TO THE NORTHEAST IN AN ELONGATED AND WEAKENED FASHION...MOVING THROUGH THE GREAT LAKES REGION ON FRIDAY. GOOD WARM/MOISTURE ADVECTION OVER SOUTHEAST MICHIGAN WITH ISENTROPIC LIFT EXPECTED TO LEAD TO OVERRUNNING PRECIPITATION LATE THURSDAY NIGHT AND FRIDAY. THINKING PRECIPITATION WILL BE MOSTLY/ALL RAIN EVENT DURING/BY FRIDAY. EVEN IF ONE GOES WITH THE COLDER 12Z GFS SOLUTION...BASED ON THE 1000-850 MB THICKNESSES...ONLY THE NORTHERN THUMB AND TRI- CITIES REGION IS HOVERING AROUND 1305 M OR SLIGHTLY COLDER (12Z FRIDAY). THE 12Z UKMET IS INDICATING THICKNESSES A GOOD 15 METERS HIGHER WITH THERMAL RIDGE MOVING IN DURING THE DAY.

THE FORECAST FOR THE WEEKEND THEN BECOMES VERY COMPLICATED AS A TIGHT BAROCLINIC ZONE SETS UP OVER THE GREAT LAKES REGION IN THE WAKE OF FRIDAY`S WAVE. THE DEPTH OF THE COLD AIR MOVING INTO SOUTHERN LOWER MICHIGAN FRIDAY NIGHT AND SATURDAY WILL BE CRITICAL FOR THE POTENTIAL SIGNIFICANT STORM LATE IN THE WEEKEND AS LARGE SURFACE HIGH SLIDES ACROSS EASTERN CANADA.

12Z GFS...GLOBAL CANADIAN...AND EUROPEAN ARE ALL GENERALLY SHOWING THE SAME CONCEPT...WITH THE ALL IMPORTANT DETAILS SIGNIFICANTLY DIFFERENT. LARGE UPPER LOW OVER THE CENTRAL/SOUTHERN ROCKIES ON SATURDAY WITH POLAR VORTEX OVER NORTH CENTRAL CANADA DROPPING SOUTH. THESE TWO SYSTEMS ARE EXPECTED TO PHASE...WITH THE TIMING OF THIS OCCURRENCE AND THE POSITION OF THE PREVIOUSLY MENTIONED BAROCLINIC ZONE DICTATING THE TRACK OF THE SURFACE LOW EJECTING FROM THE PLAINS. THE 12Z EUROPEAN AND GLOBAL CANADIAN ARE THE FARTHEST WEST AND WARMEST...AS THE SURFACE LOW TRACKS THROUGH SOUTHERN LOWER MICHIGAN. IT SHOULD BE NOTED THE CANADIAN IS MUCH SLOWER AND DEEPER. BOTH THESE SOLUTIONS WOULD CALL FOR MOSTLY A RAIN EVENT...WHICH COULD LEAD TO FLOODING WITH THE RIVERS RUNNING HIGH.

THE 12Z GFS IS INDICATING A TRACK THROUGH NORTHERN OHIO/NORTHWEST PENNSYLVANIA...WHICH IS JUST ABOUT THE IDEAL TRACK FOR A MAJOR WINTER EVENT OVER SOUTHEAST MICHIGAN. BASED ON THE 12Z EUROPEAN TRENDING SLIGHTLY FARTHER EAST THAN IT`S 00Z RUN...FELT A COMPROMISED TRACK ALONG OR NEAR THE DETROIT RIVER ON SUNDAY IS THE BEST WAY TO GO AT THIS TIME. THIS TRACK WOULD STILL RESULT IN A WINTRY MESS ACROSS THE NORTH HALF OF THE CWA...WITH MOSTLY RAIN ACROSS THE SOUTH HALF.

ARCTIC AIR WILL THEN SWEEP IN BEHIND THE SYSTEM EARLY NEXT WEEK...WITH LAKE EFFECT SNOW SHOWERS/FLURRIES A GOOD BET. DEPENDING ON THE SNOWPACK...MAX TEMPS COULD BE STUCK IN THE TEENS ON TUESDAY.

&&

.DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...GALE WARNING...SOUTH HALF UNTIL 7 AM WEDNESDAY.

SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING SAGINAW BAY UNTIL 7 AM WEDNESDAY.

LAKE ST CLAIR...SMALL CRAFT ADVISORY...LCZ460 UNTIL 7 AM WEDNESDAY.

MI WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY...UNTIL 7 AM WEDNESDAY.

&&

$$

SHORT TERM...SHULER LONG TERM....SF AVIATION...CONSIDINE

YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

.SHORT TERM (TODAY AND TONIGHT)... WATER VAPOR LOOP SHOWS A LONG WAVE TROUGH MOVING EAST OF THE REGION...WITH A RIDGE ACROSS THE ROCKIES. ACARS 400-250MB WIND OBSERVATIONS REVEAL A NORTHWEST JET OF 140-170KT FEEDING INTO THE BASE OF THE TROUGH FROM SOUTH CENTRAL CANADA THROUGH THE MID ATLANTIC. 04Z SURFACE ANALYSIS PLACED A TROUGH IN THE LEE OF THE APPALACHIANS...WITH A 1032MB ANTICYCLONE ACROSS THE SOUTH CENTRAL CONUS. SEVERAL NEARLY STATIONARY WEST-EAST BOUNDARIES WERE DRAPED ACROSS SOUTH CENTRAL CANADA AND UPPER MIDWEST.

WHILE 03Z SHORT RANGE ENSEMBLES AND 00Z NAM INDICATE ADDITIONAL SNOW WATER EQUIVALENT OF A TENTH OF AN INCH ACROSS THE MOUNTAINS EARLY THIS MORNING...NATIONAL RADAR LOOP SHOWS STREAMERS STILL COMING OFF THE GREAT LAKES. HAVE THEREFORE EXTENDED THE SNOW ADVISORY UNTIL 10:00 AM FOR AN ADDITIONAL 1-2" OF SNOW IN THE FAVORED UPSLOPE LOCATIONS. WITH ANTICYCLONIC FLOW SUPPORTED BY RIDGE BUILDING IN THIS AFTERNOON...WARM ADVECTION AND LOW LEVEL SHEAR WILL DIMINISH REMAINING SNOW SHOWERS AND MUCH OF THE UPSLOPE CLOUDINESS.

EAST OF THE MOUNTAINS...STEEP LOW LEVEL LAPSE RATES ARE SUPPORTING ISOLATED FLURRIES EARLY THIS MORNING. THESE FLURRIES WILL DIMINISH SHORTLY AFTER SUNRISE AS UPSLOPE SNOW SHOWERS BECOME LESS NUMEROUS AND EFFICIENT. CLOUDS WILL BE BREAKING EARLY THIS MORNING...WITH SOME REDEVELOPMENT OF CUMULUS DURING THE LATE MORNING. WITH STRONG COLD ADVECTION...WENT BELOW MOS FOR HIGH TEMPERATURES.

SKY WILL BECOME CLEAR ACROSS THE REGION BY LATE EVENING AS HIGH PRESSURE SURFACE AND ALOFT SETTLES INTO THE MID ATLANTIC. LOOSENING GRADIENT WILL ALLOW WINDS TO DECOUPLE...AND WITH DRY AIRMASS WILL SEE GREAT RADIATIONAL COOLING. ANTICIPATE SINGLE DIGITS IN FAR WESTERN VALLEYS...MID TEENS RURAL AREAS...LOW TO MID 20S ACROSS THE CITIES AND UPPER TEENS ABOVE 2500FT.

&&

.AVIATION... GRADIENT WILL SUPPORT NW WIND GUSTS TO 25KTS TODAY...WITH ISOLATED FLURRIES POSSIBLE FROM STRATOCU DECK NORTH OF KCHO EARLY THIS MORNING (NO REDUCTION OF CEILINGS OR VISIBILITIES ARE ANTICIPATED). BUILDING RIDGE WILL ALLOW CLOUDS TO DIMINISH AS WINDS DECOUPLE THIS EVENING.

&&

.MARINE... 00Z GFS/ETA MOS AT THOMAS POINT BOTH SUGGEST SUSTAINED WINDS WILL BE IN THE 19-22KT RANGE TODAY...AND AROUND 10KT RANGE TONIGHT. 00Z NAM/GFS PROXIMITY LAND BUFKIT FORECAST SOUNDINGS SUGGEST ADDITIONAL WIND GUST MOMENTUM OF 24-28KT. WILL HAVE WINDS OF 20-25KT IN THE FORECAST TODAY...WITH THE SMALL CRAFT ADVISORY CONTINUING UNTIL EARLY EVENING.

PARTIAL DOWNSLOPE THU NIGHT INTO FRI AND A DECENT PRES GRAD BEHIND THE DEPARTING HIGH PRES. CONCERNED ABOUT POSSIBLE SCA WINDS DEVELOPING BUT FOR NOW NOT HIGH ENOUGH CONFIDENCE AND NOT ANY PERSUASIVE MODEL WIND DATA ATTM TO MENTION IN THE FCST...WILL JUST NEED TO KEEP AN EYE ON LATER RUNS.

GRAD TIGHTENS AGAIN AROUND SUNDAY BETWEEN OH VLY LOW AND ATLC HIGH AND GOOD SW WINDS...WITH ANOTHER POSSIBLE SCA HEADLINE.

&&

.TIDES... WATER LEVELS ARE CURRENTLY A QUARTER FOOT ABOVE ASTRONOMIC PREDICTIONS. THE LUNAR CYCLE IS WANING TOWARD A QUARTER MOON (63% FULL). THE CHESAPEAKE BAY OPERATIONAL FORECAST SYSTEM AND NOAA EXTRATROPICAL STORM SURGE MODEL FORECAST WATER LEVELS TO FALL TO DEPARTURES OF ONE FOOT BELOW ASTRONOMIC WATER LEVELS THIS AFTERNOON WITH STRONG NORTHWEST FLOW.

&&

.LONG TERM...THURSDAY THROUGH TUESDAY...

THU-FRI HIGH PRES WILL MOVE OFFSHORE AND ALLOW WARM SW FLOW TO DEVELOP ACROSS THE MID ATLANTIC. 850 WINDS WILL INCREASE TO NEAR 50 KT ON SUN AS A WARM FRONT MOVES NORTH OF THE REGION ASSOCIATED WITH THE DEEPENING LOW OVER THE LOWER OHIO VALLEY. STILL MOISTURE TRANSPORT OVER THE VIRGINIAS IS PRETTY POOR AND DON`T SEE MUCH IN THE WAY OF PRECIPITATION FOR THE STERLING CWFA IN THIS WARM SECTOR...TIL THE STRONG COLD FRONT APPROACHES SUN NIGHT. BETTER CHANCES ON MONDAY AS FRONT DEVELOPS AN IMPRESSIVE POOL OF LIFT ACROSS MD/VA. WITH SOME RUN-RUN CONSISTENCY IN MONDAY PRECIP CHANCES HAVE INCREASED POPS TO BETWEEN 40 TO 50 ACROSS THE CWFA. COLDER AIR WILL FILTER IN MONDAY NIGHT AND ESPECIALLY TUESDAY...WILL CONTINUE TO INDICATE SNOW MIXING IN DURING THE TAIL OF THE PRECIP MONDAY NIGHT WITH SOME UPSLOPE SNOW SHOWERS POSSIBLE ALONG THE ALLEGHENY FRONT ON TUESDAY. HAVE BACKED OFF THE POPS PREVIOUSLY INDICATED TUE AND TUE NIGHT EAST OF THE RIDGE WHERE MOISTURE WILL PROBABLY BE LACKING.

TEMPS WILL BE WELL ABOVE NORMAL FRI THROUGH MON IN SOUTHWESTERLY FLOW. 00Z GFS AND ESPECIALLY THE LATEST ECMWF CONTINUE TO SHOW A NICE CHUNK OF ARCTIC AIR DROPPING INTO THE MIDWEST WITH THIS SYSTEM MON-TUE...BUT STILL NOT CONVINCED AIRMASS WILL REMAIN INTACT OR FOR THAT MATTER MAKE IT TO THE MID ATLANTIC TO BRING US SOME MORE REALISTIC MID-WINTER CONDITIONS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR MDZ501.

VA...SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ021.

WV...SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR WVZ054-501-503.

MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR ANZ530>537.

&&

$$

SHORT TERM/HYDROLOGY/AVIATION/TIDES...ROGOWSKI LONG TERM...BROTHERTON MARINE...ROGOWSKI/BROTHERTON

.DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW TROF OVER ERN NAMERICA DOWNSTREAM OF UPR RDG BLDG INTO THE NRN PLAINS IN ADVANCE OF POTENT SHRTWV CRASHING INTO THE PAC NW (12Z-24Z H3 HGT FALL UP TO 250M IN NW WA STATE). CWA EARLY THIS MRNG REMAINS DOMINATED BY COLD AND GUSTY LLVL NW FLOW BTWN SFC HI PRES RDG APRCHG THE MS RIVER VALLEY AND DEEP LO PRES OVER QUEBEC. H85 TEMPS UPSTREAM STILL AS LO AS -21C AT YPL. ALTHOUGH LLVLS AT THIS SITE ARE RELATIVELY MOIST...ABSOLUTE MSTR IS LIMITED WITH SFC DWPTS BLO 0F IN MN AND ONTARIO NW OF LK SUP. 00Z INL SDNG IS QUITE A BIT DRIER THAN THE YPL SDNG CLOSER TO RDG AXIS...AND SKIES ARE MOCLR NOW IN THE MN ARROWHEAD. DESPITE THE VIGOROUS CAD OVER THE UPR LKS...THE COMBINATION OF THIS DRY AIR AND LO INVRN ARND H9 AS SHOWN ON THE 00Z INL/YPL RAOBS AS WELL AS TAMDAR SDNGS AT DLH/YQT HAVE NEGATIVELY IMPACTED LES AMTS EVEN OVER THE ERN ZNS WHERE LONGER FETCH ACRS THE LK HAS ALLOWED MORE LLVL MOISTENING AND DEEPER MIXED LYR UP TO H8 AS SHOWN ON THE 00Z TAMDAR SDNG FM SAW. NO MORE THAN 3-4 INCHES OF SN HAS FALLEN THRU 04Z. FARTHER UPSTREAM...MID/HI CLD IN WAD AHEAD OF SHRTWV MOVING INTO THE PAC NW HAS SPREAD THRU THE UPR RDG INTO NW MN. 00Z BIS SDNG IS QUITE DRY BLO H8...SO LEADING EDGE OF LGT SN TRAILS WELL BEHIND IN SE SASKATCHEWAN AT 04Z.

MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND LES TRENDS. FOCUS THEN SHIFTS TO TIMING/IMPACT OF SHRTWV NOW MOVING INTO THE PAC NW WITH CHC OF -SN AS EARLY AS THIS AFTN.

FOR TDAY...NUMERICAL GUIDANCE SHOWS H5 HGT RISES UP TO 120M AS RDG IN THE PLAINS CONTINUES TO BLD EWD. SFC RDG AXIS PROGGED TO REACH NR IWD AT 12Z BEFORE PUSHING E OF ANJ BY 00Z THU. AS THE RDG AXIS/LOWER INVRN HGT APRCH FM THE W...EXPECT ONGOING LES TO END AND WINDS TO DIMINISH W-E. HAVE OPTED TO EXTEND THE LES ADVY (WITHOUT THE BLSN) OVER THE E A FEW HRS TO ACCOUNT FOR FVRBL CONDITIONS FOR MORE SHSN INTO MID MRNG. OTRW...BRIEF CLRG WL GIVE WAY TO INCRSG HI/MID CLD WITH ONSET OF ISENTROPIC ASCENT AS SHOWN ON THE 280-300K SFCS. SINCE LLVLS ON THE BIS SDNG ARE SO DRY AND ISENTROPIC ASCENT APPEARS TO BE THE ONLY FORCING MECHANISM FOR UPWARD MOTION WITH DPVA/UPR DVGC ASSOCIATED WITH SHRTWV NOW MOVING INTO THE PAC NW REMAINING TO THE NW THRU 00Z (SHRTWV ITSELF FCST TO REACH SE SASKATCHEWAN AT 00Z)... HAVE OPTED TO TAKE OUT THE WAD POPS TDAY OVER THE ENTIRE CWA PER VARIOUS MOS FCSTS. RESOLVE STRENGTHENED BECAUSE ISENTROPIC LIFT APPEARS TO BE GOING MORE TOWARD HORIZONTAL TEMP ADVCTN VS UVV AS PRES FCST TO RISE STEADILY ON THE ISENTROPIC SFCS IN QUESTION (I.E. STEADY WARMING)...NOT SURPRISING CONSIDERING TRACK OF SHRTWV WELL TO THE NW. OTRW...VARIOUS MOS FCST HI TEMPS CONSISTENT WITH READINGS EXPECTED FM EXPLICIT GFS FCST SDNGS.

TNGT...SHRTWV OVER SRN CANADA FCST TO MOVE INTO NW ONTARIO BY 12Z THU. THERE IS SOME DISCREPANCY WITH REGARD TO THE POSITION OF SFC LO BY 12Z...WITH NAM FARTHEST TO THE NW JUST E OF LK WINNIPEG AND UKMET FARTHEST TO THE S NR DLH. 00Z GFS/12Z ECMWF LOOK TO BE A RSNBL COMPROMISE BTWN THESE SOLNS WITH SFC LO JUST N OF INL. GFS SHOWS BEST ISENTROPIC LIFT AS WELL AS DPVA/SHARPER H85-5 QVECTOR CNVGC/UPR DVGC TO THE N. CONSIDERING THE PLACEMENT OF THESE BETTER DYNAMICS AND LINGERING DRY AIR...HAVE OPTED TO RESTRICT CHC POPS TO OVER THE NRN TIER AND DOWNWIND OF LK MI WHERE STRONG SLY FLOW WL BE ABLE TO PICK UP SOME MSTR IN LONG FETCH OVER LK. IN FACT...GFS FCST SDNG FOR ERY AT 06Z SHOWS RELATIVELY DEEP MSTR...SO HIEST CHC POPS IN THIS LOCATION. OTRW...EXPECT RELATIVELY LTL DIURNAL VARIATION OF TEMP WITH STRG SLY FLOW...GFS SHOWS H925 WINDS UP TO 35-40 KTS. WL ISSUE GALE WRNG FOR LK SUP AS THIS LLJ MOVES OVHD TO THE S OF AREA OF SHARP PRES FALLS MOVING ACRS ONTARIO.

ON THU...SHRTWV/SFC LO FCST TO SHEAR TO THE ENE...DRAGGING SFC COLD FNT TO THE E AND SCNTRL ZNS BY LATE IN THE DAY. ALTHOUGH SOME LLVL MSTR REMAINS...DRYING ALF IN JET SURGE REGION UNDER H85-5 QVECTOR DVGC SUGS ANY PCPN WL BE ON THE LGT SIDE. TEMPTED TO RESTRICT POPS TO JUST THE N AND E DURING THE MRNG BEFORE DEEPER MSTR EXITS... BUT 00Z GFS HINTS SOME UPR DVGC IN RRQ OF JET PASSING TO THE NE WL CAUSE AN AXIS OF HIER H7 RH OVER THE FNT LATER IN THE DAY OVER THE SCNTRL AND E. SINCE SEVERAL OTHER OPS MODELS ARE SLOWER PUSHING THE FNT THROUGH UNDER SW FLOW ALF PARALLEL TO SFC BNDRY...WL RETAIN AT LEAST A 20 POP OVER THE ENTIRE FA. WL ALSO INCLUDE MIX WITH RA OVER THE SCNTRL AS SFC TEMPS WL RISE WELL ABV 32 AND FCST SNDGS HINT AT SUFFICIENT DEPTH OF ABV FRZG NR SFC LYR TO JUSTIFY LIQUID PCPN. WITH RELATIVELY WARM START...THU LOOKS TO BE THE WARMEST DAY OF THE WEEK EVEN THOUGH CONSIDERABLE CLD COVER WL RESTRICT DIURNAL TEMP RISE.

COLDER AIR FCST TO GRDLY FILTER BACK INTO UPR MI THU NGT/FRI AS UPR FLOW GRDLY VEERS FM SW TO MORE W WITH TIME. BUT GFS/UKMET HINT THAT RRQ OF UPR JET IN CONFLUENCE ZN BTWN NRN AND SRN BRANCHES WL REMAIN OVER THE FA WITH A POCKET OF HIER H7 RH NEAR FOCUSED H8-7 FGEN WELL TO THE N OF RELATIVELY SHALLOW ARCTIC INTRUSION. ALTHOUGH NLY FLOW OF ARCTIC AIR APPEARS TO BE RATHER DRY...WL MAINTAIN SOME CHC POPS DURING THIS TIME FOR EITHER THE FGEN FORCING OR LES POTENTIAL. CONSIDERING THE FAIRLY HI STABILITY AND SHARP H8-7 FGEN...HAVE TRENDED DOWN ON FCST TEMPS THU NGT/FRI PER GFS FCST SDNGS AND GFS/ETA MOS GUIDANCE.

MUCH UNCERTAINTY REMAINS IN THE LATER PDS AS TO INTERACTION BTWN NRN BRANCH AND SRN BRANCH CLOSED LO OVER THE DESERT SW. LATEST GUIDANCE HAS TRENDED A BIT SLOWER WITH EJECTION OF THIS FEATURE...SO ADDED LO CHC POPS OVER THE SCNTRL ZNS ON SUN NGT/MON TO MATCH SURROUNDING OFFICES.

COORDINATED WITH APX/GRB/DLH.

&&

.MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVY UNTIL 15Z WED MIZ006-007-085. GALE WRNG E 1/2 LK SUP. &&

$$ KC

UPDATE...MID MRNG UPDATE ONLY INVOLVED THE END OF THE SNOW ADVSRY FOR THE FAR WRN ZNS. CAMERAS IN FAR WRN MD/ERN WV SHOW IMPRVG CONDITIONS.

WOODY!

****

SHORT TERM (TODAY AND TONIGHT)... WATER VAPOR LOOP SHOWS A LONG WAVE TROUGH MOVING EAST OF THE REGION...WITH A RIDGE ACROSS THE ROCKIES. ACARS 400-250MB WIND OBSERVATIONS REVEAL A NORTHWEST JET OF 140-170KT FEEDING INTO THE BASE OF THE TROUGH FROM SOUTH CENTRAL CANADA THROUGH THE MID ATLANTIC. 04Z SURFACE ANALYSIS PLACED A TROUGH IN THE LEE OF THE APPALACHIANS...WITH A 1032MB ANTICYCLONE ACROSS THE SOUTH CENTRAL CONUS. SEVERAL NEARLY STATIONARY WEST-EAST BOUNDARIES WERE DRAPED ACROSS SOUTH CENTRAL CANADA AND UPPER MIDWEST.

WHILE 03Z SHORT RANGE ENSEMBLES AND 00Z NAM INDICATE ADDITIONAL SNOW WATER EQUIVALENT OF A TENTH OF AN INCH ACROSS THE MOUNTAINS EARLY THIS MORNING...NATIONAL RADAR LOOP SHOWS STREAMERS STILL COMING OFF THE GREAT LAKES. HAVE THEREFORE EXTENDED THE SNOW ADVISORY UNTIL 10:00 AM FOR AN ADDITIONAL 1-2" OF SNOW IN THE FAVORED UPSLOPE LOCATIONS. WITH ANTICYCLONIC FLOW SUPPORTED BY RIDGE BUILDING IN THIS AFTERNOON...WARM ADVECTION AND LOW LEVEL SHEAR WILL DIMINISH REMAINING SNOW SHOWERS AND MUCH OF THE UPSLOPE CLOUDINESS.

EAST OF THE MOUNTAINS...STEEP LOW LEVEL LAPSE RATES ARE SUPPORTING ISOLATED FLURRIES EARLY THIS MORNING. THESE FLURRIES WILL DIMINISH SHORTLY AFTER SUNRISE AS UPSLOPE SNOW SHOWERS BECOME LESS NUMEROUS AND EFFICIENT. CLOUDS WILL BE BREAKING EARLY THIS MORNING...WITH SOME REDEVELOPMENT OF CUMULUS DURING THE LATE MORNING. WITH STRONG COLD ADVECTION...WENT BELOW MOS FOR HIGH TEMPERATURES.

SKY WILL BECOME CLEAR ACROSS THE REGION BY LATE EVENING AS HIGH PRESSURE SURFACE AND ALOFT SETTLES INTO THE MID ATLANTIC. LOOSENING GRADIENT WILL ALLOW WINDS TO DECOUPLE...AND WITH DRY AIRMASS WILL SEE GREAT RADIATIONAL COOLING. ANTICIPATE SINGLE DIGITS IN FAR WESTERN VALLEYS...MID TEENS RURAL AREAS...LOW TO MID 20S ACROSS THE CITIES AND UPPER TEENS ABOVE 2500FT.

AVIATION... GRADIENT WILL SUPPORT NW WIND GUSTS TO 25KTS TODAY.

MARINE... WILL HAVE WINDS OF 20-25KT IN THE FORECAST TODAY...WITH THE SMALL CRAFT ADVISORY CONTINUING UNTIL EARLY EVENING.

PARTIAL DOWNSLOPE THU NIGHT INTO FRI AND A DECENT PRES GRAD BEHIND THE DEPARTING HIGH PRES. CONCERNED ABOUT POSSIBLE SCA WINDS DEVELOPING BUT FOR NOW NOT HIGH ENOUGH CONFIDENCE AND NOT ANY PERSUASIVE MODEL WIND DATA ATTM TO MENTION IN THE FCST...WILL JUST NEED TO KEEP AN EYE ON LATER RUNS.

GRAD TIGHTENS AGAIN AROUND SUNDAY BETWEEN OH VLY LOW AND ATLC HIGH AND GOOD SW WINDS...WITH ANOTHER POSSIBLE SCA HEADLINE.

LONG TERM...THURSDAY THROUGH TUESDAY...

THU-FRI HIGH PRES WILL MOVE OFFSHORE AND ALLOW WARM SW FLOW TO DEVELOP ACROSS THE MID ATLANTIC. 850 WINDS WILL INCREASE TO NEAR 50 KT ON SUN AS A WARM FRONT MOVES NORTH OF THE REGION ASSOCIATED WITH THE DEEPENING LOW OVER THE LOWER OHIO VALLEY. STILL MOISTURE TRANSPORT OVER THE VIRGINIAS IS PRETTY POOR AND DON`T SEE MUCH IN THE WAY OF PRECIPITATION FOR THE STERLING CWFA IN THIS WARM SECTOR...TIL THE STRONG COLD FRONT APPROACHES SUN NIGHT. BETTER CHANCES ON MONDAY AS FRONT DEVELOPS AN IMPRESSIVE POOL OF LIFT ACROSS MD/VA. WITH SOME RUN-RUN CONSISTENCY IN MONDAY PRECIP CHANCES HAVE INCREASED POPS TO BETWEEN 40 TO 50 ACROSS THE CWFA. COLDER AIR WILL FILTER IN MONDAY NIGHT AND ESPECIALLY TUESDAY...WILL CONTINUE TO INDICATE SNOW MIXING IN DURING THE TAIL OF THE PRECIP MONDAY NIGHT WITH SOME UPSLOPE SNOW SHOWERS POSSIBLE ALONG THE ALLEGHENY FRONT ON TUESDAY. HAVE BACKED OFF THE POPS PREVIOUSLY INDICATED TUE AND TUE NIGHT EAST OF THE RIDGE WHERE MOISTURE WILL PROBABLY BE LACKING.

TEMPS WILL BE WELL ABOVE NORMAL FRI THROUGH MON IN SOUTHWESTERLY FLOW. 00Z GFS AND ESPECIALLY THE LATEST ECMWF CONTINUE TO SHOW A NICE CHUNK OF ARCTIC AIR DROPPING INTO THE MIDWEST WITH THIS SYSTEM MON-TUE...BUT STILL NOT CONVINCED AIRMASS WILL REMAIN INTACT OR FOR THAT MATTER MAKE IT TO THE MID ATLANTIC TO BRING US SOME MORE REALISTIC MID-WINTER CONDITIONS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR ANZ530>537.

&&

$$

.UPDATE...DID AN ERLY MRNG UPDT OF ZNS/EOL TO REMOVE MENTION OF FLURRIES IN METRO AREAS. SNOW ADVSRY FAR W REMAINS IN EFFECT.

WOODY! ****

.SHORT TERM (TODAY AND TONIGHT)... WATER VAPOR LOOP SHOWS A LONG WAVE TROUGH MOVING EAST OF THE REGION...WITH A RIDGE ACROSS THE ROCKIES. ACARS 400-250MB WIND OBSERVATIONS REVEAL A NORTHWEST JET OF 140-170KT FEEDING INTO THE BASE OF THE TROUGH FROM SOUTH CENTRAL CANADA THROUGH THE MID ATLANTIC. 04Z SURFACE ANALYSIS PLACED A TROUGH IN THE LEE OF THE APPALACHIANS...WITH A 1032MB ANTICYCLONE ACROSS THE SOUTH CENTRAL CONUS. SEVERAL NEARLY STATIONARY WEST-EAST BOUNDARIES WERE DRAPED ACROSS SOUTH CENTRAL CANADA AND UPPER MIDWEST.

WHILE 03Z SHORT RANGE ENSEMBLES AND 00Z NAM INDICATE ADDITIONAL SNOW WATER EQUIVALENT OF A TENTH OF AN INCH ACROSS THE MOUNTAINS EARLY THIS MORNING...NATIONAL RADAR LOOP SHOWS STREAMERS STILL COMING OFF THE GREAT LAKES. HAVE THEREFORE EXTENDED THE SNOW ADVISORY UNTIL 10:00 AM FOR AN ADDITIONAL 1-2" OF SNOW IN THE FAVORED UPSLOPE LOCATIONS. WITH ANTICYCLONIC FLOW SUPPORTED BY RIDGE BUILDING IN THIS AFTERNOON...WARM ADVECTION AND LOW LEVEL SHEAR WILL DIMINISH REMAINING SNOW SHOWERS AND MUCH OF THE UPSLOPE CLOUDINESS.

EAST OF THE MOUNTAINS...STEEP LOW LEVEL LAPSE RATES ARE SUPPORTING ISOLATED FLURRIES EARLY THIS MORNING. THESE FLURRIES WILL DIMINISH SHORTLY AFTER SUNRISE AS UPSLOPE SNOW SHOWERS BECOME LESS NUMEROUS AND EFFICIENT. CLOUDS WILL BE BREAKING EARLY THIS MORNING...WITH SOME REDEVELOPMENT OF CUMULUS DURING THE LATE MORNING. WITH STRONG COLD ADVECTION...WENT BELOW MOS FOR HIGH TEMPERATURES.

SKY WILL BECOME CLEAR ACROSS THE REGION BY LATE EVENING AS HIGH PRESSURE SURFACE AND ALOFT SETTLES INTO THE MID ATLANTIC. LOOSENING GRADIENT WILL ALLOW WINDS TO DECOUPLE...AND WITH DRY AIRMASS WILL SEE GREAT RADIATIONAL COOLING. ANTICIPATE SINGLE DIGITS IN FAR WESTERN VALLEYS...MID TEENS RURAL AREAS...LOW TO MID 20S ACROSS THE CITIES AND UPPER TEENS ABOVE 2500FT.

&&

.AVIATION... GRADIENT WILL SUPPORT NW WIND GUSTS TO 25KTS TODAY...WITH ISOLATED FLURRIES POSSIBLE FROM STRATOCU DECK NORTH OF KCHO EARLY THIS MORNING (NO REDUCTION OF CEILINGS OR VISIBILITIES ARE ANTICIPATED). BUILDING RIDGE WILL ALLOW CLOUDS TO DIMINISH AS WINDS DECOUPLE THIS EVENING.

&&

.MARINE... 00Z GFS/ETA MOS AT THOMAS POINT BOTH SUGGEST SUSTAINED WINDS WILL BE IN THE 19-22KT RANGE TODAY...AND AROUND 10KT RANGE TONIGHT. 00Z NAM/GFS PROXIMITY LAND BUFKIT FORECAST SOUNDINGS SUGGEST ADDITIONAL WIND GUST MOMENTUM OF 24-28KT. WILL HAVE WINDS OF 20-25KT IN THE FORECAST TODAY...WITH THE SMALL CRAFT ADVISORY CONTINUING UNTIL EARLY EVENING.

PARTIAL DOWNSLOPE THU NIGHT INTO FRI AND A DECENT PRES GRAD BEHIND THE DEPARTING HIGH PRES. CONCERNED ABOUT POSSIBLE SCA WINDS DEVELOPING BUT FOR NOW NOT HIGH ENOUGH CONFIDENCE AND NOT ANY PERSUASIVE MODEL WIND DATA ATTM TO MENTION IN THE FCST...WILL JUST NEED TO KEEP AN EYE ON LATER RUNS.

GRAD TIGHTENS AGAIN AROUND SUNDAY BETWEEN OH VLY LOW AND ATLC HIGH AND GOOD SW WINDS...WITH ANOTHER POSSIBLE SCA HEADLINE.

&&

.LONG TERM...THURSDAY THROUGH TUESDAY...

THU-FRI HIGH PRES WILL MOVE OFFSHORE AND ALLOW WARM SW FLOW TO DEVELOP ACROSS THE MID ATLANTIC. 850 WINDS WILL INCREASE TO NEAR 50 KT ON SUN AS A WARM FRONT MOVES NORTH OF THE REGION ASSOCIATED WITH THE DEEPENING LOW OVER THE LOWER OHIO VALLEY. STILL MOISTURE TRANSPORT OVER THE VIRGINIAS IS PRETTY POOR AND DON`T SEE MUCH IN THE WAY OF PRECIPITATION FOR THE STERLING CWFA IN THIS WARM SECTOR...TIL THE STRONG COLD FRONT APPROACHES SUN NIGHT. BETTER CHANCES ON MONDAY AS FRONT DEVELOPS AN IMPRESSIVE POOL OF LIFT ACROSS MD/VA. WITH SOME RUN-RUN CONSISTENCY IN MONDAY PRECIP CHANCES HAVE INCREASED POPS TO BETWEEN 40 TO 50 ACROSS THE CWFA. COLDER AIR WILL FILTER IN MONDAY NIGHT AND ESPECIALLY TUESDAY...WILL CONTINUE TO INDICATE SNOW MIXING IN DURING THE TAIL OF THE PRECIP MONDAY NIGHT WITH SOME UPSLOPE SNOW SHOWERS POSSIBLE ALONG THE ALLEGHENY FRONT ON TUESDAY. HAVE BACKED OFF THE POPS PREVIOUSLY INDICATED TUE AND TUE NIGHT EAST OF THE RIDGE WHERE MOISTURE WILL PROBABLY BE LACKING.

TEMPS WILL BE WELL ABOVE NORMAL FRI THROUGH MON IN SOUTHWESTERLY FLOW. 00Z GFS AND ESPECIALLY THE LATEST ECMWF CONTINUE TO SHOW A NICE CHUNK OF ARCTIC AIR DROPPING INTO THE MIDWEST WITH THIS SYSTEM MON-TUE...BUT STILL NOT CONVINCED AIRMASS WILL REMAIN INTACT OR FOR THAT MATTER MAKE IT TO THE MID ATLANTIC TO BRING US SOME MORE REALISTIC MID-WINTER CONDITIONS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR MDZ501.

VA...SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ021.

WV...SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR WVZ054-501-503.

MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR ANZ530>537.

&&

$$

SHORT TERM/HYDROLOGY/AVIATION/TIDES...ROGOWSKI LONG TERM...BROTHERTON MARINE...ROGOWSKI/BROTHERTON

.UPDATE...

LES IS WINDING DOWN STEADILY THIS MORNING AS HIGH PRES RIDGE MOVES ACROSS THE AREA. RIDGE CURRENTLY RUNS FROM LAKE MICHIGAN TO CNTRL LAKE SUPERIOR. UPSTREAM...VIGOROUS SHORTWAVE HEADING INTO SRN SASKATCHEWAN IS LEADING TO STRONG WAA PATTERN OVER THE NRN PLAINS. 12Z SOUNDING AT KBIS SHOWED 850MB TEMP OF 7C WITH SW WIND AT 35KT WHILE KINL/CYQD HAD 850MB TEMPS OF -11/-19C RESPECTIVELY. WAA/ISENTROPIC ASCENT REGIME HAS RESULTED IN MID CLOUD DECK FROM THE DAKOTAS ACROSS NRN MN. RADARS SHOW RETURNS FROM CLOUD DECK...BUT ONLY A FEW OBS HAVE SHOWN ANY SNOW IN NRN MN AS DRY AIRMASS PER 12Z KINL SOUNDING HAS KEPT MUCH OF THE SNOW FROM REACHING THE GROUND.

LAST OF THE LES SHOULD END OVER THE FAR NE FCST AREA DURING THE NEXT FEW HRS AS WINDS BACK OFFSHORE WITH PASSAGE OF RIDGE AXIS. STRONG WAA REGIME WILL THEN BEGIN TO SPREAD E INTO WRN UPPER MI DURING THE AFTN...BUT EXPECT DRY AIR TO DELAY ONSET OF -SN SIGNIFICANTLY. RECENT TAMDAR SOUNDING FROM KSAW SHOWED DWPT DEPRESSIONS FROM 10 TO 25C BTWN 900 AND 700MB. INHERITED FCST LOOKED FINE JUST BRINGING CHC -SN TO WRN LAKE SUPERIOR DURING THE AFTN.

&&

.PREV DISCUSSION... ISSUED AT 335 AM EST

00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW TROF OVER ERN NAMERICA DOWNSTREAM OF UPR RDG BLDG INTO THE NRN PLAINS IN ADVANCE OF POTENT SHRTWV CRASHING INTO THE PAC NW (12Z-24Z H3 HGT FALL UP TO 250M IN NW WA STATE). CWA EARLY THIS MRNG REMAINS DOMINATED BY COLD AND GUSTY LLVL NW FLOW BTWN SFC HI PRES RDG APRCHG THE MS RIVER VALLEY AND DEEP LO PRES OVER QUEBEC. H85 TEMPS UPSTREAM STILL AS LO AS -21C AT YPL. ALTHOUGH LLVLS AT THIS SITE ARE RELATIVELY MOIST...ABSOLUTE MSTR IS LIMITED WITH SFC DWPTS BLO 0F IN MN AND ONTARIO NW OF LK SUP. 00Z INL SDNG IS QUITE A BIT DRIER THAN THE YPL SDNG CLOSER TO RDG AXIS...AND SKIES ARE MOCLR NOW IN THE MN ARROWHEAD. DESPITE THE VIGOROUS CAD OVER THE UPR LKS...THE COMBINATION OF THIS DRY AIR AND LO INVRN ARND H9 AS SHOWN ON THE 00Z INL/YPL RAOBS AS WELL AS TAMDAR SDNGS AT DLH/YQT HAVE NEGATIVELY IMPACTED LES AMTS EVEN OVER THE ERN ZNS WHERE LONGER FETCH ACRS THE LK HAS ALLOWED MORE LLVL MOISTENING AND DEEPER MIXED LYR UP TO H8 AS SHOWN ON THE 00Z TAMDAR SDNG FM SAW. NO MORE THAN 3-4 INCHES OF SN HAS FALLEN THRU 04Z. FARTHER UPSTREAM...MID/HI CLD IN WAD AHEAD OF SHRTWV MOVING INTO THE PAC NW HAS SPREAD THRU THE UPR RDG INTO NW MN. 00Z BIS SDNG IS QUITE DRY BLO H8...SO LEADING EDGE OF LGT SN TRAILS WELL BEHIND IN SE SASKATCHEWAN AT 04Z.

MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND LES TRENDS. FOCUS THEN SHIFTS TO TIMING/IMPACT OF SHRTWV NOW MOVING INTO THE PAC NW WITH CHC OF -SN AS EARLY AS THIS AFTN.

FOR TDAY...NUMERICAL GUIDANCE SHOWS H5 HGT RISES UP TO 120M AS RDG IN THE PLAINS CONTINUES TO BLD EWD. SFC RDG AXIS PROGGED TO REACH NR IWD AT 12Z BEFORE PUSHING E OF ANJ BY 00Z THU. AS THE RDG AXIS/LOWER INVRN HGT APRCH FM THE W...EXPECT ONGOING LES TO END AND WINDS TO DIMINISH W-E. HAVE OPTED TO EXTEND THE LES ADVY (WITHOUT THE BLSN) OVER THE E A FEW HRS TO ACCOUNT FOR FVRBL CONDITIONS FOR MORE SHSN INTO MID MRNG. OTRW...BRIEF CLRG WL GIVE WAY TO INCRSG HI/MID CLD WITH ONSET OF ISENTROPIC ASCENT AS SHOWN ON THE 280-300K SFCS. SINCE LLVLS ON THE BIS SDNG ARE SO DRY AND ISENTROPIC ASCENT APPEARS TO BE THE ONLY FORCING MECHANISM FOR UPWARD MOTION WITH DPVA/UPR DVGC ASSOCIATED WITH SHRTWV NOW MOVING INTO THE PAC NW REMAINING TO THE NW THRU 00Z (SHRTWV ITSELF FCST TO REACH SE SASKATCHEWAN AT 00Z)... HAVE OPTED TO TAKE OUT THE WAD POPS TDAY OVER THE ENTIRE CWA PER VARIOUS MOS FCSTS. RESOLVE STRENGTHENED BECAUSE ISENTROPIC LIFT APPEARS TO BE GOING MORE TOWARD HORIZONTAL TEMP ADVCTN VS UVV AS PRES FCST TO RISE STEADILY ON THE ISENTROPIC SFCS IN QUESTION (I.E. STEADY WARMING)...NOT SURPRISING CONSIDERING TRACK OF SHRTWV WELL TO THE NW. OTRW...VARIOUS MOS FCST HI TEMPS CONSISTENT WITH READINGS EXPECTED FM EXPLICIT GFS FCST SDNGS.

TNGT...SHRTWV OVER SRN CANADA FCST TO MOVE INTO NW ONTARIO BY 12Z THU. THERE IS SOME DISCREPANCY WITH REGARD TO THE POSITION OF SFC LO BY 12Z...WITH NAM FARTHEST TO THE NW JUST E OF LK WINNIPEG AND UKMET FARTHEST TO THE S NR DLH. 00Z GFS/12Z ECMWF LOOK TO BE A RSNBL COMPROMISE BTWN THESE SOLNS WITH SFC LO JUST N OF INL. GFS SHOWS BEST ISENTROPIC LIFT AS WELL AS DPVA/SHARPER H85-5 QVECTOR CNVGC/UPR DVGC TO THE N. CONSIDERING THE PLACEMENT OF THESE BETTER DYNAMICS AND LINGERING DRY AIR...HAVE OPTED TO RESTRICT CHC POPS TO OVER THE NRN TIER AND DOWNWIND OF LK MI WHERE STRONG SLY FLOW WL BE ABLE TO PICK UP SOME MSTR IN LONG FETCH OVER LK. IN FACT...GFS FCST SDNG FOR ERY AT 06Z SHOWS RELATIVELY DEEP MSTR...SO HIEST CHC POPS IN THIS LOCATION. OTRW...EXPECT RELATIVELY LTL DIURNAL VARIATION OF TEMP WITH STRG SLY FLOW...GFS SHOWS H925 WINDS UP TO 35-40 KTS. WL ISSUE GALE WRNG FOR LK SUP AS THIS LLJ MOVES OVHD TO THE S OF AREA OF SHARP PRES FALLS MOVING ACRS ONTARIO.

ON THU...SHRTWV/SFC LO FCST TO SHEAR TO THE ENE...DRAGGING SFC COLD FNT TO THE E AND SCNTRL ZNS BY LATE IN THE DAY. ALTHOUGH SOME LLVL MSTR REMAINS...DRYING ALF IN JET SURGE REGION UNDER H85-5 QVECTOR DVGC SUGS ANY PCPN WL BE ON THE LGT SIDE. TEMPTED TO RESTRICT POPS TO JUST THE N AND E DURING THE MRNG BEFORE DEEPER MSTR EXITS... BUT 00Z GFS HINTS SOME UPR DVGC IN RRQ OF JET PASSING TO THE NE WL CAUSE AN AXIS OF HIER H7 RH OVER THE FNT LATER IN THE DAY OVER THE SCNTRL AND E. SINCE SEVERAL OTHER OPS MODELS ARE SLOWER PUSHING THE FNT THROUGH UNDER SW FLOW ALF PARALLEL TO SFC BNDRY...WL RETAIN AT LEAST A 20 POP OVER THE ENTIRE FA. WL ALSO INCLUDE MIX WITH RA OVER THE SCNTRL AS SFC TEMPS WL RISE WELL ABV 32 AND FCST SNDGS HINT AT SUFFICIENT DEPTH OF ABV FRZG NR SFC LYR TO JUSTIFY LIQUID PCPN. WITH RELATIVELY WARM START...THU LOOKS TO BE THE WARMEST DAY OF THE WEEK EVEN THOUGH CONSIDERABLE CLD COVER WL RESTRICT DIURNAL TEMP RISE.

COLDER AIR FCST TO GRDLY FILTER BACK INTO UPR MI THU NGT/FRI AS UPR FLOW GRDLY VEERS FM SW TO MORE W WITH TIME. BUT GFS/UKMET HINT THAT RRQ OF UPR JET IN CONFLUENCE ZN BTWN NRN AND SRN BRANCHES WL REMAIN OVER THE FA WITH A POCKET OF HIER H7 RH NEAR FOCUSED H8-7 FGEN WELL TO THE N OF RELATIVELY SHALLOW ARCTIC INTRUSION. ALTHOUGH NLY FLOW OF ARCTIC AIR APPEARS TO BE RATHER DRY...WL MAINTAIN SOME CHC POPS DURING THIS TIME FOR EITHER THE FGEN FORCING OR LES POTENTIAL. CONSIDERING THE FAIRLY HI STABILITY AND SHARP H8-7 FGEN...HAVE TRENDED DOWN ON FCST TEMPS THU NGT/FRI PER GFS FCST SDNGS AND GFS/ETA MOS GUIDANCE.

MUCH UNCERTAINTY REMAINS IN THE LATER PDS AS TO INTERACTION BTWN NRN BRANCH AND SRN BRANCH CLOSED LO OVER THE DESERT SW. LATEST GUIDANCE HAS TRENDED A BIT SLOWER WITH EJECTION OF THIS FEATURE...SO ADDED LO CHC POPS OVER THE SCNTRL ZNS ON SUN NGT/MON TO MATCH SURROUNDING OFFICES.

COORDINATED WITH APX/GRB/DLH.

&&

.MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING E HALF OF LAKE SUPERIOR. &&

$$

ROLFSON (UPDATE) KC (PREV DISCUSSION)

.DISCUSSION....EARLY THIS AFTERNOON...LATEST SURFACE/RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW HIGH PRESSURE OVER THE SOUTHERN PLAINS WHOSE SURFACE RIDGE AXIS BISECTS LOWER MICHIGAN. LOW LEVEL WINDS STARTING TO REFLECT THE AXIS PASSAGE WITH LIGHT LAKE EFFECT SNOW SHOWERS OVER NW LOWER AND TIP OF THE MITT DIMINISHING AS THE DISORGANIZED BANDS ARE TRYING TO ORIENT THEMSELVES IN THE SW-NE DIRECTION. THESE BANDS ARE ALSO FIGHTING PLENTY OF DRY AIR AS ACARS SOUNDINGS FROM PLN AND TVC SHOW INVERSION HEIGHTS CONTINUING TO FALL TO AROUND 860MB. AWAY FROM THE LES BANDS...SKIES HAVE TURNED PARTLY TO MOSTLY SUNNY. MEANWHILE UPSTREAM...STRONG SHORTWAVE NOW OVER ALBERTA AND ASSOCIATED LOW PRESSURE IS TRUCKING EAST ALONG THE CANADIAN BORDER...HELPING TO TIGHTEN THE PRESSURE GRADIENT OVER THE PLAINS. WARM AIR ADVECTION CLOUDS RIDING OVER THE 850MB WARM FRONT LOCATED OVER THE UPPER MISSISSIPPI RIVER VALLEY ARE STARTING TO CROSS LAKE MICHIGAN...AND WILL EVENTUALLY MAKE IT ACROSS THE CWA LATE THIS AFTERNOON/EVENING. THE INTERACTION OF THIS WARM FRONT AS IT MOVES NORTHEAST TONIGHT...AND WEAKENING LES WILL BE THE MAIN FORECAST CONCERN TONIGHT.

TONIGHT...UPSTREAM SHORTWAVE WILL MAKE IT TO MANITOBA (ASSOCIATED SURFACE LOW PRESSURE TO WESTERN ONTARIO) BY 12Z THURSDAY MORNING. THIS WAVE WILL HELP INCREASE THE SOUTHERLY FLOW AHEAD OF IT AND PUSH A 850MB WARM FRONT TO THE NORTHEAST TO NORTHERN LOWER BY 12Z. AS IT DOES SO...850MB TEMPERATURES MODERATE ALOT FROM MINUS 6-9C AT 00Z OVER NORTHERN LAKE MICHIGAN TO 0 TO MINUS 3 BY 12Z. A SURGE OF MOISTURE WILL ACCOMPANY THIS WAA...WHICH REDUCES CONDENSATION PRESSURE DEFICITS ON THE 285K AND 290K ISENTROPIC SURFACES TO LESS THAN 10MB BY APPROXIMATELY 03Z. NAM/GFS SOUNDINGS DIFFER OVERNIGHT...WITH THE NAM NOT NEARLY AS MOIST BELOW 800MB AS THE GFS. WITH ONSHORE FLOW OVER EASTERN UPPER FROM LAKE MICHIGAN WHILE DELTA T/S REMAINING ABOVE 8C DURING THE EVENING...LIKE THE MORE MOIST SCENARIO DEPICTED BY THE GFS...AND WILL KEEP CHANCE POPS ACROSS EASTERN UPPER AFTER 03Z. LOWER LEVELS LOOK TO DRY OVER NORTHERN LOWER FOR PRECIP AT THIS TIME. TEMPERATURES WILL BOTTOM OUT DURING THE EVENING TONIGHT BUT THEN SLOWLY RISE OVERNIGHT WITH THE INCOMING WARM AIR.

MARINE...TIGHTENING PRESSURE GRADIENT COMBINED WITH OVER-LAKE INSTABILITY AND COASTAL CONVERGENCE WILL CREATE WIND SPEEDS AT 925MB TO 40-50KTS TONIGHT AND GALE FORCE WIND GUSTS ALONG THE LAKE MICHIGAN SHORELINE FROM MANISTEE TO THE STRAITS. ELSEWHERE...MIXING TO 925MB REVEALS WIND GUSTS COULD POTENTIALLY REACH BETWEEN 30-35 KNOTS...OR JUST BELOW GALE FORCE...SO WILL INTRODUCE SMALL CRAFTS EVERYWHERE ELSE.

MPC

FOR THE REMAINDER OF THE WEEK...COLD AIR CONTINUES TO MODERATE AND RAPIDLY MOVE EAST OF THE REGION EARLY ON WHILE LOW AMPLITUDE MID LEVEL RIDGING DEVELOPS OVER THE EASTERN STATES...BUT NEXT CORE OF COLD AIR DESCENDS INTO THE NRN ROCKIES. ONE PIECE OF ENERGY (NOW NEAR LAKE WINNIPEG) FORECAST TO MOVE ACROSS SOUTHERN CANADA WITH AN ASSOCIATED LOW PRESSURE SYSTEM AND COLD FRONT SLOWING MOVING THROUGH AND IMPACTING THE REGION THURSDAY THROUGH FRIDAY. MAIN FORECAST ISSUES FOR THE NEAR TERM REVOLVE AROUND PRECIP CHANCES AND TYPE AS THIS SYSTEM PASSES THROUGH.

THURSDAY...AS MENTIONED ABOVE...NRN STREAM SHORTWAVE AND ASSOCIATED SFC LOW FORECAST TO SLOWLY MOVE INTO ONTARIO DURING THE DAY...WITH A WARM FRONT LIFTING THROUGH THE REGION OVERNIGHT/EARLY THURSDAY AND TRAILING COLD FRONT APPROACHING THE REGION BY LATE AFTERNOON. DECENT SHOT OF WARM ADVECTION MAY BE ENOUGH TO PRODUCE BAND OF LIGHT SNOWFALL ACROSS EASTERN UPPER MICHIGAN THURSDAY MORNING AND WILL KEEP A CHANCE GOING IN THE FORECAST FOR THAT AREA...ALTHOUGH LOWER LAYERS ARE A BIT ON THE DRY SIDE. BUT WITHOUT ANY HELP FROM THE LAKES (TEMPS TOO WARM) ANY ACCUMULATIONS SHOULD BE ON THE LIGHT SIDE. THURSDAY AFTERNOON...NORTHERN MICHIGAN WELL INTO THE WARM SECTOR WITH STRONG SW WINDS CONTINUING AND AFTERNOON TEMPS WARMING BACK INTO THE 30S TO AROUND 40 (WOULD BE EVEN WARMER WERE IT NOT FOR THE SNOW COVER). MEANWHILE...BOTH NAM AND PARTICULARLY THE GFS DEPICT SUBSTANTIAL MOISTENING IN THE SUB 800 MB LAYER DURING THE AFTERNOON (WARMER THAN -6C) AHEAD OF THE APPROACHING FRONT...WHILE MOISTURE ALOFT STRIPS OUT. NOT MUCH OUT THERE UPSTREAM TODAY IN TERMS OF LOW CLOUDS TO HANG YOUR HAT ON...BUT CAN SEE THIS TAKING SHAPE AS WARMER/MOIST AIR SURGES NORTH ACROSS THE SNOW COVER IN NORTHERN MICHIGAN. REMOVED MENTION OF ANY RAIN/SNOW FROM THE FORECAST FOR THE AFTERNOON...BUT MAY BE ENOUGH MOISTURE THERE TO GET SOME DRIZZLE GOING ESPECIALLY ACROSS THE HIGHER TERRAIN AREAS.

THURSDAY NIGHT THROUGH FRIDAY...COLD FRONT SLOWLY PRESSES EAST/SE THROUGH THE AREA THURSDAY NIGHT INTO EARLY FRIDAY AND SETTLE TO OUR SOUTH. ALTHOUGH STILL QUITE A BIT OF UNCERTAINLY REGARDING POPS DURING THIS TIMEFRAME...PERHAPS ENOUGH FORCING/MOISTURE ALONG THE FRONT TO SQUEEZE OUT MEASURABLE PRECIP BOTH THURSDAY NIGHT INTO FRIDAY...WITH PRIMARILY SNOW OVER THE NRN TWO-THIRDS OF THE CWA AND RAIN/SNOW OVER THE SOUTH. ALSO...AS COLDER AIR SLOWLY FILTERS INTO THE REGION...SHOULD START TO GET THE LAKES MORE INVOLVED BY FRIDAY. BUT OVERALL ACCUMULATIONS LOOKING TO BE ON THE MINOR SIDE AT THIS POINT.

SATURDAY THRU WEDNESDAY...FRONT CONTINUES TO SAG SOUTH OF THE REGION BY EARLY SATURDAY WITH COLDER AIR ONCE AGAIN SETTLING INTO THE STATE FOR THE WEEKEND. SPLIT FLOW REGIME EMERGES ACROSS THE LOWER 48 STATES BY THE END OF THE WEEK AND HEADING INTO THE WEEKEND...WITH A CLOSED MID LEVEL LOW SLOWLY DROPPING SOUTHWARD ALONG THE WEST COAST INTO THE 4 CORNERS REGION AND LOW AMPLITUDE RIDGING OVER THE EASTERN HALF OF THE CONUS. LATEST MEDIUM RANGE GUIDANCE SUGGESTS BROAD NRN STREAM HIGH PRESSURE WILL SETTLE ACROSS THE NRN PLAINS AND WESTERN GREAT LAKES SATURDAY INTO EARLY SUNDAY WITH TEMPS RUNNING NEAR NORMAL. STILL COLD ENOUGH HOWEVER FOR SOME LIGHT LAKE SNOW SHOWERS DURING THIS TIME ALTHOUGH PROBLEMATIC THIS FAR OUT TO PINPOINT THE EXACT FLOW REGIME AND LOCATIONS WITH THE BEST CHANCES FOR SNOW. BY LATE IN THE WEEKEND AND EARLY NEXT WEEK...SRN STREAM CUTOFF SYSTEM LOOKING TO LIFT THROUGH THE OHIO VALLEY AND INTO NEW ENGLAND. SYSTEM COULD PRODUCE A DECENT AMOUNT OF SNOW (SYSTEM AND LAKE ENHANCED) ACROSS LOWER MICHIGAN IF CURRENT SCENARIO PANS OUT. THEN AGAIN... MEDIUM RANGE SOLUTIONS HAVE SHOWN A GOOD AMOUNT OF UNCERTAINTY WITH REGARD TO LOCATION OF THE STORM TRACK AND TIMING/LOCATION OF DEEPENING WAVES RIDING ALONG THE BAROCLINIC ZONE UP THROUGH THE REGION. BEHIND THIS SYSTEM AS IT STANDS RIGHT NOW...SOME OF THE COLDEST AIR OF THE YEAR GETS PULLED INTO NRN MICHIGAN FOR TUESDAY AND WEDNESDAY...WHILE STRONG HIGH PRESSURE BUILDS INTO THE PLAINS AND WESTERN GREAT LAKES. HOWEVER...WITH THE COLD AIR IN PLACE WILL HAVE CONTINUING CHANCES FOR SNOW SHOWERS.

ADAM

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.APX...WATCHES/WARNINGS/ADVISORIES...GALE WARNING...TONIGHT THROUGH THURSDAY....LMZ323-342-344-345.

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