FXUS61 KRLX 092033
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
333 PM EST WED DEC 9 2009
.SYNOPSIS...
STRONG AND GUSTY WINDS WILL DIMINISH THIS EVENING 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/...
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 /20Z WEDNESDAY THROUGH MONDAY/...
18Z WEDNESDAY THRU 18Z THURSDAY...
MAIN FEATURE IS THE STRONG WINDS EXPECTED AHEAD OF AND BEHIND COLD
FRONTAL PASSAGE TODAY. EXPECT SUSTAINED WINDS OF 20 TO 30KTS WITH
GUSTS OF UP TO 50 KTS. HIGHEST GUSTS/WINDS CAN BE EXPECTED OVER THE
HIGHER TERRAIN...WHERE GUSTS OF UP TO 60KTS CAN BE EXPECTED. WINDS
WILL SLOWLY DIMINISH THIS EVENING...BUT WILL STILL BE A FACTOR
THROUGH THE PERIOD.
COLD FRONT CURRENTLY MOVING ACROSS THE AREA THIS AFTERNOON...
EXITING THE MOUNTAINS OF WV BY 22Z. A LINE OF RAIN SHOWERS AND AN
ISOLATED THUNDERSTORM MAY ACCOMPANY THE FRONT...FOLLOWED BY WIDELY
SCATTERED TO SCATTERED POST FRONTAL RAIN SHOWERS. EXPECT MAINLY VFR
CEILINGS AROUND 3500 FEET...BUT OCCASIONAL MVFR CEILINGS IN
SCATTERED SHOWERS THIS AFTERNOON. ANY LINGERING RAIN SHOWERS WILL
BEGIN TO CHANGE OVER TO SNOW AFTER 21Z.
AFTER 00Z EXPECT MVFR/ISOLD IFR CONDITIONS IN SNOW SHOWERS...MAINLY
IN THE MOUNTAINS. ELSEWHERE MAINLY VFR CEILINGS.
AFTER 18Z THURSDAY...
WINDS WILL STILL BE MODERATE DURING THURSDAY. BRIEF IFR CONDITIONS
WILL BE POSSIBLE IN THE MOUNTAINS IN MORNING SNOW SHOWERS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR WVZ005>011-
013>020-024>032-039-040.
HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR WVZ033>038-
046-047.
OH...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR OHZ066-067-075-
076-083>087.
KY...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR KYZ101>103-105.
VA...HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR VAZ003-004.
&&
$$
SYNOPSIS...KMC/MDP/JMV
NEAR TERM...JMV
SHORT TERM...KMC
LONG TERM...MDP
AVIATION...JMV
