FXUS61 KRLX 071524
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
1024 AM EST MON DEC 7 2009
.SYNOPSIS...
WEAK FRONT WITH LIMITED MOISTURE TODAY. WARM FRONTAL PRECIPITATION
TUESDAY AFTERNOON AND NIGHT. STRENGTHENING LOW PRESSURE LIFTS
NORTHEAST INTO GREAT LAKES WEDNESDAY WITH FRONT PASSING.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...BAND OF LIGHT SNOW SHOWERS WILL FINISH TRAVERSING THE CWA
IN THE NEXT HOUR OR TWO. CANNOT RULE OUT LINGERING
FLURRIES/SPRINKLES ONCE THE LINE PASSES FOR THE REMAINDER OF THE
DAY. TEMPERATURES SHOULD CLIMB ABOVE FREEZING FAIRLY QUICKLY IN
THE NEXT COUPLE OF HOURS.
MID AND HIGH CLOUDS WILL CONTINUE TO INCREASE THIS MORNING AS A
SHORTWAVE...CURRENTLY MOVING INTO IL...APPROACHES THE REGION. THIS
SHORTWAVE...AND ASSOCIATED WEAK FRONTAL BOUNDARY...HAS GENERATED
LIGHT SNOW SHOWERS ACROSS MUCH OF CENTRAL IL OVERNIGHT...WITH RAIN
IN KY AND AREAS SOUTH. THIS SHORTWAVE WILL SHEAR APART AS IT MOVES
INTO THE OHIO VALLEY THIS MORNING...WITH MOISTURE BECOMING LIMITED
AS IT DOES SO. MODEL SOUNDINGS INDICATE PRECIPITATION IN THE FORM OF
RAIN ACROSS MOST OF THE FORECAST AREA TODAY...EXCEPT FOR A BRIEF
PERIOD OF SNOW SHOWERS OR A RAIN/SNOW MIX THIS MORNING OVER SE
OHIO...BEFORE CHANGING TO ALL RAIN LATER THIS MORNING. MOUNTAIN
ZONES WILL SEE SNOW OR A RAIN/SNOW MIX AT ELEVATIONS ABOVE 2000
FEET...CHANGING TO ALL SNOW LATER IN THE EVENING. WITH OVERALL LACK
OF DEEP MOISTURE...ANY PRECIPITATION THAT DOES OCCUR WILL BE
LIGHT...GENERALLY LESS THAN A TENTH OF AN INCH. PRECIPITATION WILL
TAPER OFF ACROSS THE CWA TONIGHT AS THE SHORTWAVE AND ASSOCIATED
FRONTAL BOUNDARY CONTINUE TO MOVE EAST. HOWEVER...A FEW UPSLOPE
SHOWERS WILL CONTINUE TO PERSIST TONIGHT OVER THE HIGHER
TERRAIN...IN THE WESTERLY FLOW ALOFT.
TUESDAY MORNING LOW TEMPS A BIT TRICKY TO FORECAST FOR AS AMOUNT OF
CLEARING WILL BE SOMEWHAT OF A DETERMINING FACTOR...BUT THINKING
ENOUGH CLOUD COVER SHOULD BE STREAMING IN IN ADVANCE OF THE NEXT
SYSTEM...IN ADDITION TO GOOD SOUTHWESTERLY FLOW...TO NOT ALLOW FOR
TOO GREAT OF A DIP IN TEMPERATURE. HAVE KEPT LOW TEMPS GENERALLY IN
THE UPPER 20 TO LOWER 30 FORECAST RANGE AS A RESULT. SEVERAL OF THE
MODELS ALSO INDICATE SOME LIGHT PATCHY FOG FORMING TOMORROW MORNING.
THIS CERTAINLY IS NOT OUT OF THE QUESTION CONSIDERING THE MOIST
BOUNDARY LAYER FROM RECENT SNOWFALL...AND WILL DEPEND ON THE AMOUNT
OF CLEARING.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
STRONG SHORT WAVE TROUGH THAT DIGS INTO NEVADA TODAY IS THE WEATHER
STORY THIS PERIOD. MODELS APPEAR A BIT FASTER WITH ITS APPROACH TO
FCST AREA TUE. PRECIPITATION SHOULD BREAK OUT AND SPREAD ACROSS
THE AREA QUICKLY TUE IN RESPONSE TO STRONG WARM ADVECTION /
ISENTROPIC LIFT COUPLED WITH GOOD UPPER LEVEL DIVERGENCE.
PRECIPITATION CONTINUES WELL INTO TUE NT UNTIL OCCLUSION SWEEPS
THROUGH EARLY WED MORNING.
COLD AIR DAMMING PER STRONG AGEOSTROPHIC FLOW IN THE SYNOPTIC SCALE
SE FLOW REGIME AHEAD OF THE SYSTEM WILL LIKELY LEAD TO FREEZING RAIN
ON THE EASTERN MOUNTAIN SLOPES FOR A TIME LATE TUE AND TUE EVE.
THE POTENTIAL FOR THIS IS A BIT LIMITED BY THE ITS AFTERNOON
ARRIVAL. IT APPEARS THIS MAY BE AN ADVISORY LEVEL EVENT AT BEST.
IN THE STRONG PRESSURE GRADIENT...STRONG WINDS ARE LIKELY TUE NIGHT
THAT MAY REQUIRE AN ADVISORY FOR GUSTS INTO THE 40S ON THE RIDGES
AND OVERTOP OF THE LOW LEVEL COLD AIR TRAPPED IN THE MOUNTAIN
VALLEYS. WILL HAVE TO WATCH THIS INTO WED MORNING WHEN OCCLUSION
PROVIDES MUCH BETTER MIXING AND DOWNWARD MOMENTUM TRANSPORT BEFORE
50KT H85 FLOW ABATES WED AFTN.
WILL CONTINUE MENTION OF BOTH HAZARDS ONGOING IN THE HWO AS WELL AS
THEIR RESPECTIVE IMPACTS IN THE RWS.
A MUCH COLDER WEATHER REGIME FOLLOWS IN THE WAKE OF THIS STRONG
SYSTEM THROUGH THE BALANCE OF THIS PERIOD WITH THE COLD AIR ARRIVING
WED. UPSLOPE RAIN SHOWERS WED WILL GO TO SNOW SHOWERS BY LATE IN
THE DAY THAT THEN CONTINUE INTO THURSDAY. DRIER AIR SHOULD TAKE
HOLD THURSDAY NIGHT.
LIKE THE LOW SIDE OF GUIDANCE IN THE STABLE DECEMBER REGIME FOR
HIGHS TUE. TEMPERATURES WILL BE NON DIURNAL TUE NIGHT AND WED AS IT
WARMS IN ADVANCE OF THE SYSTEM TUE NT AND THEN COOLS BACK DOWN WED
AFTN. THE MEX DID NOT APPEAR TO BE PICKING UP ON MUCH LOWER
TEMPERATURES ITS SOURCE MODEL SUGGESTS FOR THU AND THU NT.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
STRONG LOW PRESSURE LIFTS RAPIDLY THRU THE GREAT LAKES AND NEW
ENGLAND AT THE START OF THE PERIOD. STRONG COLD ADVECTION RAPIDLY
OVERSPREADS THE ENTIRE AREA WEDNESDAY EVENING...WITH ANY RAIN
SHOWERS CHANGING TO SNOW SHOWERS. DO NOT EXPECT MUCH OF A POST
FRONTAL WRAPAROUND SNOW EVENT OR EVEN A SIGNIFICANT UPSLOPE EVENT
WEDNESDAY NIGHT. FLOW AROUND THE DEPARTING LOW REMAINS MORE WESTERLY
WITH DEEPER MOISTURE REMAINING TO OUR NORTH. THUS...EXPECT LITTLE OR
NO SNOW ACCUMULATION IN MOST OF THE LOWLANDS...WHILE GENERALLY
LIGHT SNOW ACCUMULATIONS ARE EXPECTED IN THE NORTHERN AND CENTRAL
MOUNTAINS. THE BIGGER FACTOR WEDNESDAY NIGHT MAY BE THE GUSTY WEST
WINDS IN THE TIGHT PRESSURE GRADIENT AROUND THE LOW...ESPECIALLY
OVER SOUTHEAST OHIO AND THE HIGHER ELEVATIONS OF THE NORTHERN
MOUNTAINS. GOING A BIT COLDER THAN MOS GUIDANCE...GIVEN THE STRONG
850/950MB COLD ADVECTION.
FOR THURSDAY...HIGH PRESSURE BUILDS IN WITH LINGERING MOUNTAIN SNOW
SHOWERS RAPIDLY ENDING...WITH DECREASING CLOUDS IN THE WEST. HIGH
PRESSURE OVER THE AREA THURSDAY NIGHT WITH IDEAL RADIATIONAL
COOLING...AGAIN GOING BELOW GUIDANCE TEMP MINS.
ANOTHER MUCH WEAKER SYSTEM IN THE STRONG WESTERLY FLOW IS PROGGED TO
PASS SOUTH OF OUR AREA AROUND THE BEGINNING OF THE WEEKEND. GOING
WITH THE FASTER AND MORE SUPPRESSED GFS...WHICH MAY GIVE THE AREA A
LIGHT RAIN OR SNOW EVENT LATER FRIDAY NIGHT INTO SATURDAY
MORNING.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
12Z MONDAY THROUGH 12Z TUESDAY...
HIGH CLOUDS ALLOWING FOR PATCHY MVFR MIST TO START THIS MORNING
IMPACTING HTS-CRW-EKN.
AS THE MIST SLOWLY DISSIPATES...CIGS WILL LOWER AS A WEAK COLD FRONT
APPROACHES. LIGHT RAIN AND SNOW SHOWERS WILL MOVE INTO THE LOWLANDS
FROM THE WEST THIS MORNING...THEN CONTINUE E ACROSS CENTRAL WV...AND
THEN FINALLY REACHING THE HIGH TERRAIN BY 21Z TODAY.
THE SYSTEM MOVES OUT OF THE AREA LATER TONIGHT...BUT MVFR CIGS ARE
POSSIBLE IN THE MTNS FOR A TIME OVERNIGHT ON W UPSLOPE FLOW. THESE
CLOUDS SHOULD BREAK UP LATE TONIGHT. HIGH THIN CLOUDS LATE TONIGHT
WILL ALLOW PATCHY MIST TO FORM AGAIN...LIKELY IN THE SAME AREAS AS
THIS MORNING. THE HIGH CLOUDS WILL BEGIN TO LOWER AND THICKEN FROM
THE SW TOWARD DAWN TUE.
LIGHT SE SURFACE WINDS WILL VEER DURING THE DAY TODAY AS THE WEAK
FRONTAL BOUNDARY APPROACHES THE REGION...AND THEN BECOME W IN THE
WAKE OF THE FRONT LATE TODAY AND THIS EVENING...AND THEN LIGHT AND
VARIABLE OVERNIGHT AS A WEAK SURFACE HIGH PASSES BY. MODERATE WSW
WINDS ALOFT TODAY BECOME LIGHT WNW TONIGHT.
AFTER 12Z TUESDAY...
IFR IN MOSTLY RAIN LATE TUESDAY INTO WEDNESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...TRM/SL
NEAR TERM...26/SL
SHORT TERM...TRM
LONG TERM...JMV
AVIATION...TRM/SL
