FXUS61 KRLX 100030
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
730 PM EST WED DEC 9 2009
.SYNOPSIS...
STRONG AND GUSTY WINDS WILL DIMINISH OVERNIGHT AS THE LOW PULLS
AWAY. HIGH PRESSURE WITH COLD BUT IMPROVING WEATHER THURSDAY.
ANOTHER STORM SYSTEM MOVES IN FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH THURSDAY/...
UPDATED POPS AND EXTENDED WIND ADV/WRNG TIL 10PM. WINDS ARE JUST
BARELY AT OR BELOW ADV/WRNG CRITERIA AND WILL CONTINUE TO DIE DOWN
THE REST OF TONIGHT. DELAYED POPS EVERYWHERE AND DECREASED POPS
IN THE NORTHERN MOUNTAINS TO CHC POPS AS BULK OF WRAP AROUND SNOW
SHOWERS WON'T GET TO THE AREA FOR ANOTHER COUPLE OF HOURS AND
WESTERLY FLOW NOT OPTIMUM UPSLOPE. OTHERWISE REST OF FORECAST
LOOKS ON TRACK.
PREVIOUS DISCUSSION...
POWERFUL LOW PRESSURE SYSTEM PULLS AWAY
TONIGHT...WITH HIGH PRESSURE BUILDING IN LATER TONIGHT AND
THURSDAY. THE VERY STRONG WINDS OF THIS AFTERNOON...WHICH WERE ON
THE HIGH END OF THE WIND ADVISORY CRITERIA IN THE LOW LANDS...AND
A LITTLE ABOVE WIND WARNING CRITERIA ON SOME HILL TOP AREAS OF THE
LOWLANDS...WILL DIMINISH TO BELOW WARNING/ADVISORY CRITERIA THIS
EVENING. THIS HILL TOP FACTOR WAS ADDRESSED IN THE ADVISORY. THE
HIGH WIND WARNING OF THE MOUNTAINS...WHICH WAS EASILY
REACHED...WILL ALSO DIMINISH THIS EVENING. HOWEVER...IT WILL STILL
BE ON THE WINDY SIDE TONIGHT...EVEN AS THE LARGE LOW PRESSURE
SYSTEM PULLS AWAY.
OTHERWISE...WIDELY SCATTERED TO SCATTERED RAIN SHOWERS BEHIND THE
FRONT WILL RAPIDLY CHANGE TO SCATTERED SNOW SHOWERS THIS EVENING
ACROSS THE AREA. SINCE MOISTURE DEPTH IS SHALLOW...AND WESTERLY
WINDS ARE NOT IDEAL FOR UPSLOPE...EXPECT ANY SNOW ACCUMULATIONS
OVERNIGHT TO BE MOSTLY IN THE HIGHER ELEVATIONS OF THE NORTHERN
MOUNTAINS...UP TO 2 INCHES. GIVEN THE STRONG COLD ADVECTION...GOING
ON THE COLDER SIDE OF GUIDANCE TONIGHT.
FOR THURSDAY...STILL GUSTY AND COLD...BUT MOUNTAIN SNOW SHOWERS END
AND CLOUDS BEGIN DECREASING IN THE WEST AS THE HIGH BUILDS IN.
AGAIN...GOING ON THE COLDER SIDE OF GUIDANCE GIVEN LOW LEVEL TEMP
PROFILE.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
HIGH PRESSURE BUILDS IN WITH COLD AIR MASS REMAINING IN PLACE
THURSDAY NIGHT. GRADIENT FLOW WEAKENS...WITH UPPER LEVEL HEIGHT
FIELDS SHOWING A MORE ZONAL PATTERN...WITH GRADUALLY RISING HEIGHT
VALUES BY THE WEEKEND.
MODELS IN PRETTY GOOD AGREEMENT IN KEEPING CONDITIONS DRY TO CLOSE
OUT THE WEEK. LATEST NAM AND GFS HAVE TRENDED TOWARDS KEEPING THE
WEEKEND SYSTEM AT BAY FOR ANOTHER DAY. THIS NEXT FEATURE DUE FOR THE
WEEKEND IS A SOUTHERN STREAM SYSTEM AND WILL DEVELOPING ALONG THE
GULF COAST SATURDAY.
SLIGHTLY WARMER AIRMASS RETURNS DURING THE DAY ON SATURDAY WITH SOME
OVER-RUNNING. THUS...AN UPTICK ON THE MID TO UPPER LEVEL CLOUDS CAN
BE EXPECTED.
UNDERCUT GUIDANCE FOR BOTH MAX AND MIN TEMP VALUES INTO FRIDAY.
ADJUSTED TEMPS A LITTLE CLOSER TO MAV NUMBERS LATER IN THE PERIOD AS
NEXT SYSTEM APPROACHES.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
BUSY NEARLY ZONAL FLOW CONTINUES THROUGH THE PERIOD. MAIN CONCERN IS
OPPORTUNITY OF WINTRY MIX AGAINST THE EASTERN MOUNTAINS WITH WARM
AIR ADVECTION ON BACKSIDE OF HIGH SATURDAY NIGHT INTO SUNDAY.
ALSO...A POTENTIALLY STRONG COLD FRONT MAY PASS EARLY TUESDAY.
TREND IN MODELS IS TO SLOW DOWN WARM AIR ADVECTION PRECIPITATION
THAT COMES IN FROM THE SOUTH SATURDAY NIGHT INTO SUNDAY. ALSO
HOWEVER...MOST OF THE MOISTURE REMAINS TO OUR SOUTH. I WENT SLIGHTLY
BELOW HPC POPS TO ACCOUNT FOR THIS TREND. HOWEVER...COLD AIR DAMMING
ALONG THE EAST SLOPES OF THE WV MOUNTAINS...IS SUPPORTIVE OF
PROSPECT FOR POSSIBLE FREEZING RAIN THROUGH EARLY SUNDAY...WHILE
MOST OF THE REMAINDER OF THE AREA HAS PLAIN RAIN /PERHAPS A LITTLE
MIX IN THE NORTHERN LOWLANDS/. SO I HAVE ADDED ICE CHANCES TO THE
WEATHER GRIDS FOR THE AFFECTED AREAS. TEMPERATURES IN GENERAL WILL
BE COMPLICATED SATURDAY NIGHT...THAT IS...NON DIURNAL FOR MANY AREAS
DUE TO WARM AIR ADVECTION.
NEXT FEATURE OF INTEREST IS A COLD FRONT THAT LOOKS TO PASS THROUGH
SOMETIME IN THE LATE MONDAY NIGHT THROUGH TUESDAY MORNING TIME
FRAME. WENT ALONG WITH MID CHANCE RANGE FOR POPS...WITH MAINLY RAIN
ON FRONT END TRANSITIONING TO UPSLOPE SNOW FOR MAINLY THE MOUNTAINS
TUESDAY NIGHT INTO WEDNESDAY.
WHILE OPERATIONAL GFS AND ECMWF GENERALLY AGREE WITH THIS
SCENARIO...RUN-TO-RUN CONSISTENCY IS NOT GREAT AND THERE IS A FAIR
AMOUNT OF SPREAD IN THE ENSEMBLES. NOT SURE HOW AMPLIFIED THE
ASSOCIATED INCOMING TROUGH WILL BE...AND THE DEGREE OF COLD AIR
ADVECTION BEHIND THE FRONT INTO MIDWEEK. THE ONLY CERTAIN THING WILL
BE A STRONG TEMPERATURE GRADIENT FROM THE GREAT LAKES IN THE
NORTH...TO THE OHIO VALLEY IN THE SOUTH.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
00Z THURSDAY THRU 00Z FRIDAY...
STRONG WESTERLY WINDS WILL CONTINUE TO DECREASE OVER NIGHT...BUT
STILL BE RATHER GUSTY WITH GUSTS EXPECTED TO BE IN THE 30 TO 40
RANGE TIL AROUND 03Z THEN DIMISH OVER NIGHT WITH GUSTS IN THE 20
TO 30 KT RANGE.
EXPECT ISOLD MVFR TO IFR CONDITIONS IN SNOW SHOWERS BETWEEN 03Z
AND 12Z...MAINLY IN THE MOUNTAINS...WITH MOSTLY VFR CIGS THROUGHOUT.
AFTER 00Z FRIDAY...
WINDS WILL STILL BE MODERATE DURING THURSDAY NIGHT.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR WVZ005>011-
013>020-024>032-039-040.
HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR WVZ033>038-
046-047.
OH...WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR OHZ066-067-075-
076-083>087.
KY...WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR KYZ101>103-105.
VA...HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR VAZ003-004.
&&
$$
SYNOPSIS...KMC/MDP/JS/JMV
NEAR TERM...JS/JMV
SHORT TERM...KMC
LONG TERM...MDP
AVIATION...JS
