000
FXUS61 KRLX 200920
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
420 AM EST THU NOV 20 2008
.SYNOPSIS...
A COLD FRONT WILL PUSH SOUTHEAST THIS MORNING. UPSLOPE SNOW WILL
DEVELOP TODAY...AND CONTINUE THROUGH FRIDAY. HIGH PRESSURE RETURNS
FOR THE WEEKEND. A NEW COLD FRONT ARRIVES MONDAY.
&&
.NEAR TERM /THROUGH FRIDAY/...
COLD FRONT NEARING THE AREA WILL CROSS DURING MIDDAY AND EARLY
AFTERNOON HOURS TODAY...ALTHOUGH THE COLD AIR LAGS WAY BEHIND...NW
OF CHICAGO. THE FRONT ITSELF IS DRY OWING TO LACK OF DEEP MOISTURE
AND LOW LEVEL CONVERGENCE. PRECIPITATION EVENT WILL THEREFORE BE
LIMITED TO THE UPSLOPE DRIVEN SNOW SHOWERS. TOUGH CALL AS TO JUST
WHEN THIS GETS GOING...PARTICULARLY WITH COLD ADVECTION LAGGING.
DELAYED ONSET UNTIL LATER THIS MORNING...WITH POPS THEN GOING TO
LIKELY AND CATEGORICAL THIS AFTERNOON IN THE MOUNTAINS. SOME SHORT
RANGE LOCAL MODELS DO SUPPORT MEASURABLE PRECIPITATION BY NOON TODAY.
UPSLOPE SNOW EVENT CONTINUES THROUGH TONIGHT AND MOST OF FRIDAY.
DURING FRIDAY AFTERNOON...UPPER TROUGH SHIFTS E OF THE AREA...COLD
ADVECTION SHUTS OFF AND LOW LEVEL FLOW STARTS TO BECOME
ANTICYCLONIC. WENT WITH AN HPC / NAM BLEND ON PRECIPITATION LEANING
A LITTLE CLOSER TO HPC....AND THEN APPLYING UPSLOPE EFFECT. NAM
CONTINUES TO BE PARTICULARLY DRY WITH THIS SYSTEM AS THE LOCAL
SHORT RANGE MODELS ARE BEGINNING TO POINT OUT...INCLUDING THE WSETA
INTERESTINGLY ENOUGH.
THIS YIELDS SLIGHTLY LOWER SNOW AMOUNTS THAN PREVIOUS PACKAGE...BUT
INSPECTION OF THESE GRIDS STILL WARRANTS A WARNING FOR THE TWO
COUNTIES WITH THE HIGHEST TERRAIN IN THE AREA...WITH A THIN / COUNTY
WIDE / ENVELOP OF ADVISORIES AROUND THAT...FROM NOON TODAY THROUGH 6
PM FRI.
STRATOCUMULUS DECK PUT A MONKEY WRENCH IN TEMPERATURE FORECAST WED.
ALTHOUGH CLOUDS WILL PREVAIL AGAIN TODAY...BETTER MIXING HAS ALREADY
RESULTED IN HIGHER TEMPERATURES...BUT RISE TODAY WILL AGAIN BE
LIMITED BY CLOUDS AND...EVENTUALLY....COLD ADVECTION. HIGHS ARE A
LITTLE HIGHER THAN CURRENT TEMPERATURES AND CLOSE TO GUIDANCE AND
PREVIOUS PACKAGE...NOTWITHSTANDING THE LOW FWC IN A COUPLE OF CASES
ALBEIT WHAT HAPPENED WED IS CAUSE FOR A SECOND GLANCE THERE.
PREVIOUS PACKAGE AND CURRENT NUMBERS WERE VERY WELL CLUSTERED ON
LOWS TONIGHT. PREVIOUS FORECAST WAS AN AVERAGE OF THE NEW NUMBERS
FOR HIGHS FRIDAY SO AGAIN LITTLE CHANGE APPEARED WARRANTED.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
UPSLOPE SNOW SHOWERS SHOULD BE DIMINISH FRIDAY NIGHT AS SURFACE HIGH
PRESSURE BUILDS IN. REMAINDER OF THIS PERIOD AS THE HIGH REMAINS IN
CONTROL. MODELS INDICATE A WEAK UPPER LEVEL FEATURE WILL SLIDE BY
SATURDAY NIGHT INTO SUNDAY. HOWEVER...MOISTURE IS EXPECTED TO BE
LIMITED...AND ONLY EXPECT A FEW MORE CLOUDS WITH THIS FEATURE.
PREVIOUS MAXT/MINT NUMBERS ARE VERY SIMILAR TO THE NEW GUIDANCE FOR
MOST LOCATIONS...SO ONLY MINOR TWEAKS MADE. THE MAJOR EXCEPTION IS
LOWS FOR SATURDAY NIGHT...WHERE GUIDANCE IS SUGGESTING COLDER TEMPS
THAN PREVIOUSLY THOUGHT. HAVE TWEAKED TEMPS DOWN A FEW
DEGREES...ESPECIALLY IN THE MOUNTAINS LOCATIONS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
LATEST GFS/ECMWF CONTINUE TO INDICATE A COLD FRONT WILL PUSH
SOUTHEAST MONDAY AND MONDAY NIGHT...WITH AN UPPER LOW EXPECTED TO
IMPACT THE REGION MONDAY NIGHT INTO TUESDAY. THE ECMWF INDICATES
THE UPPER LOW WILL TRACK ACROSS SOUTHEAST OHIO AND NORTHERN WEST
VIRGINIA...WHILE THE TRACK BASED ON THE GFS IS ACROSS PENNSYLVANIA.
WHICHEVER MODEL VERIFIES...THE END RESULT WILL BE INCREASING POPS
SUNDAY NIGHT...AND THEN PRECIPITATION CHANCES CONTINUING UNTIL THE
UPPER LOW MOVES EAST. THE PRECIPITATION SHOULD END TUESDAY NIGHT AS
HIGH PRESSURE BUILDS IN. DRY WEATHER IS EXPECTED ON WEDNESDAY.
AHEAD OF THE COLD FRONT...MOST OF THE PRECIPITATION SHOULD BE IN
LIQUID FORM. HOWEVER...COLD AIR ALOFT WILL RESULT IN THE RAIN
SHOWERS CHANGING TO SNOW SHOWERS MONDAY NIGHT.
WITH SURFACE TEMPS EXPECTED TO APPROACH 40 DEGREES ACROSS THE LOWER
ELEVATIONS ON TUESDAY...WOULD THINK MUCH OF THE PRECIPITATION WOULD
CHANGE BACK TO RAIN. HOWEVER...COLD 850 MB AIR WITH TEMPS OF -6 TO
-10 DEGC WILL MOVE ACROSS THE AREA TUESDAY AND TUESDAY NIGHT. THIS
COLD AIR SHOULD ACT TO KEEP MUCH OF THE PRECIPITATION AS SNOW.
FEEL GUIDANCE FOR MONDAY HIGHS IS TOO WARM. WILL GENERALLY LEAVE
TEMPERATURES AS THEY WERE FOR THE ENTIRE PERIOD.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
06Z THURSDAY THRU 06Z FRIDAY...
WESTERN EDGE OF VFR CEILINGS...AROUND 4-5KFT...HAS SHIFTED BACK TO
THE W AND NOW ENCOMPASSES ALL SITES. OVC MAY STILL BREAK SW SITES
EVEN AS COLD FRONT MOVES THROUGH THIS MORNING. INCREASING W FLOW
EVEN AHEAD OF FRONT WILL BECOME WNW IN ITS WAKE LATER TODAY. THE
VFR STRATOCU CIGS WILL GRADUALLY LOWER AFTER THE FRONTAL PASSAGE
WITH MVFR BECOMING COMMON BY THE END OF THE DAY TODAY. SNOW SHOWERS
MAY SHOW UP LATER THIS AFTERNOON. THIS IS MOST LIKELY IN THE
MOUNTAINS WHERE VSBYS AT LEAST AS LOW AS MVFR ARE POSSIBLE THIS
EVENING.......AS THE WNW UPSLOPE FLOW KICKS IN.
AVIATION OUTLOOK /BEYOND 06Z FRIDAY/...IFR CONDITIONS MAY DEVELOP IN
THE MOUNTAINS IN SNOW SHOWERS LATER OVERNIGHT THURSDAY NIGHT INTO
FRIDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 PM EST FRIDAY FOR
WVZ036>040.
WINTER STORM WARNING FROM NOON TODAY TO 6 PM EST FRIDAY FOR
WVZ046-047.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...TRM/JSH
NEAR TERM...TRM
SHORT TERM...JSH
LONG TERM...JSH
AVIATION...TRM
