FXUS61 KRLX 112049
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
345 PM EST FRI DEC 11 2009
.SYNOPSIS...
HIGH PRESSURE YIELDS DRY AND WARMER WEATHER THROUGH
SATURDAY. ANOTHER SYSTEM PASSES SOUTHWEST TO NORTHEAST SUNDAY
MORNING. COLD FRONT TUESDAY.
&&
.NEAR TERM /THROUGH SATURDAY/...
NOT MUCH TO TALK ABOUT IN THE NEAR TERM. SFC HIGH WILL GRADUALLY
SLIDE EAST OF THE CWA THROUGH SAT. MID DECK FROM EARLIER TDY WILL
CONT TO SHIFT SOUTH AND EAST OF THE AREA THIS AFTN. WINDS SHOULD
FINALLY DIMINISH OVERNIGHT. THIS SHOULD ALLOW FOR A GOOD RADIATIONAL
COOLING SETUP. ONLY CAVEAT IS A MINOR PUFF AT TOP OF BL WITH A
FEW HIGH CLOUDS TOWARD DAWN. WAA WILL ALSO BE COMMENCING...WITH H85
TEMPS COMING UP TO ARND -5C BY MORNING. DIDNT GET TOO CARRIED
AWAY CONSIDERING...HOWEVER DID GENERALLY GO A FEW DEGREES BELOW
MAV...CLOSER TO LCL MOS. THIS GIVE LWR-MID TEENS OUTSIDE OF
MTNS...WITH SOME SINGLE DIGITS POSSIBLE ACROSS THE MORE PROTECTED
AREAS OF GREENBRIER VALLEY. TRIED TO CODE UP A NON-DIURNAL ACROSS
THE HIGHEST ELEVATIONS...IE SNOWSHOE...TO ACCOUNT FOR INCREASING
WAA BY MORNING.
HIGH AND MID CLOUDS WILL BE ON THE INCREASE
THROUGHOUT THE DAY SAT FRM SW TO NE...AS NEXT SYSTEM APPROACHES.
CODED UP A BLEND OF MET AND INHERITED NUMBERS FOR MAXT
SAT...GIVING LWR- MID 40S OUTSIDE OF THE MTNS.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
MAIN CONCERN IS POTENTIAL FOR BRIEF LIGHT FREEZING RAIN EVENT EARLY
SUNDAY MORNING IN THE EASTERN SLOPES OF THE CENTRAL TO NORTHERN WV
MOUNTAINS.
WELL ADVERTISED SHORTWAVE TRAVELS THROUGH THE WEST-SOUTHWEST FLOW
ALOFT SATURDAY NIGHT THROUGH SUNDAY MORNING. MODELS ARE PRETTY MUCH
IN AGREEMENT NOW ON THIS EVENT...WHICH WILL BE PURELY DRIVEN BY
UPPER LEVEL FEATURES. 700MB PETTERSSEN FRONTOGENESIS AXIS MARKS WHAT
EFFECTIVELY IS A WARM FRONT ALOFT. ON THE NAM AT 06Z SUNDAY IT IS
JUST ABOUT TO ENTER THE AREA FROM THE SOUTHWEST...AND BY 12Z SUNDAY
IS ALREADY MUCH OF THE WAY THROUGH THE CWA...ORIENTED ROUGHLY FROM
PERRY COUNTY OH TO SNOWSHOE. HOWEVER...THERE IS NO COUPLING WITH ANY
SURFACE FEATURES...AND Q VECTOR CONVERGENCE LAGS BY SEVERAL
HOURS...AND IS ALSO MAINLY TO OUR NORTHWEST.
THAT BEING SAID...OUR AREA IS WITHIN THE RIGHT ENTRANCE REGION OF
THE 300MB JET. OVERALL...PRECIPITATION AMOUNTS WILL BE LIMITED TO A
FEW TENTHS OF AN INCH BY THE SPEED OF THE SYSTEM...AND BY RELATIVE
LACK OF PHASING OF THE UPPER LEVEL FEATURES.
VAST MAJORITY OF THE AREA WILL ONLY SEE PLAIN RAIN BECAUSE OF THE
STRONG WARM AIR ADVECTION...BUT TEMPERATURES IN THE EASTERN UPSLOPE
REGION OF THE CENTRAL TO NORTHERN WV MOUNTAINS...ESPECIALLY THE
GREENBRIER VALLEY...WILL BE COLD ENOUGH AT THE ONSET FOR SOME
FREEZING RAIN. I FEEL COLD AIR DAMMING AGAINST THE EASTERN
SLOPES...WHILE PRESENT...WILL NOT BE VERY STRONG OF THE COLD SURFACE
HIGH BEING LOCATED DUE EAST OFFSHORE THE MIDATLANTIC...INSTEAD OF
OVER NEW ENGLAND WHICH WOULD BE MORE FAVORABLE. SO WHILE FREEZING
RAIN IS LIKELY AT FIRST FOR THE EASTERN SLOPES...THERE SHOULD BE A
FAIRLY QUICK TRANSITION TO PLAIN RAIN EVEN FOR THOSE LOCATIONS BY
MID MORNING SUNDAY BECAUSE OF THE RELATIVELY GREATER STRENGTH OF THE
WARM AIR ADVECTION ALOFT. IN FACT...WINDS AT 850MB WILL BE FROM THE
SOUTH-SOUTHWEST AROUND 40-50KTS SUNDAY MORNING. THE VERY STABLE LOW
LEVEL ATMOSPHERIC PROFILE WILL PREVENT IT FROM MIXING TO THE SURFACE
FOR THE LOWLANDS...BUT THE HIGHER RIDGES AND LOCATIONS SUCH AS
SNOWSHOE MAY HAVE SOME STRONG GUSTS.
RAIN QUICKLY DIMINISHES SUNDAY AFTERNOON AS WAVE QUICKLY EXITS.
SURFACE HIGH BRIEFLY PASSES SUNDAY NIGHT...TO MONDAY MORNING...WHILE
WARM AIR ADVECTION FROM THE SOUTHWEST CONTINUES ALOFT THROUGH
MONDAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
MINOR DISCREPANCIES NOTED FROM MODELS DEPICTING COLD FRONT PUSHING
EAST LATE MONDAY NIGHT/EARLY TUESDAY. THE GFS IS FASTER WITH THE
VORT MAX ENERGY ALOFT...CLOSELY FOLLOWED BY THE ECMWF...AND THEN BY
THE GEM. HPC GUIDANCE SEEMS TO FOLLOW THE GFS/ECMWF WHICH ARE THE
PREFERRED SOLUTIONS.
MODELS SHOW DEEP SOUTHWEST FLOW BRINGING WARM ADVECTION TO THE AREA
MON NGT. WITH H850 TEMPS AROUND 3C...AND SOME CLOUDS MOVING
IN...EXPECT WARMER TEMPS THAN GMOS/HPC FOR LOWS ON TUE NGT.
CONSEQUENTLY...DELAYED THE ONSET OF WINTRY PCPN...ALLOWING
STRATIFORM RAIN TO SPREAD ACROSS THE AREA MON NGT. ON TUE...STRONG
H850 COLD AIR ADVECTION TAKES PLACE SUGGESTED BY GFS/ECMWF ALLOWING
FOR A NON DIURNAL TEMPERATURES TREND AND HIGH TEMPS IN THE UPPER
40S.
PCPN WILL TRANSITION TO WINTRY MIX OVER THE NORTHEAST MOUNTAINS TUE
EVENING....TO ALL SNOW LATER TUE NIGHT...WHILE THE REST OF THE
LOWLANDS WILL REMAIN LIQUID.
ON WED AND THU...NORTHWEST FLOW WILL TRANSFORM ANY LINGERING
MOISTURE LEFT WEST OF THE MOUNTAINS...AND COMING FROM THE GREAT
LAKES TO UPSLOPE SNOW. THEREFORE...KEPT CHANCE POPS AT ELEVATIONS
HIGHER THAN 2500 FEET.
GENERALLY WENT AT OR BELOW HPC NUMBERS FOR TEMPS THRU THE PERIOD.
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
VFR THROUGH THE PERIOD COURTESY OF HIGH PRESSURE. SFC WINDS WILL
DIMINISH OVERNIGHT WITH GENERALLY LIGHT WINDS EXPECTED ON SAT. LIGHT
TO MODERATE WSW WINDS ALOFT SAT.
AFTER 18Z SATURDAY...
IFR POSSIBLE IN RAIN SATURDAY NIGHT AND SUNDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...MDP/ARJ/30
NEAR TERM...30
SHORT TERM...MDP
LONG TERM...ARJ
AVIATION...30
