FXUS61 KRLX 091433
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
920 AM EST WED DEC 9 2009
.SYNOPSIS...
STRONG COLD FRONT WITH GUSTY WINDS WILL MOVE THROUGH THE REGION
TODAY. COLDER WITH RAIN CHANGING TO SNOW TONIGHT. HIGH PRESSURE
THURSDAY NIGHT AND FRIDAY. LOW PRESSURE THIS WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
MORNING UPDATE...WELL DEFINED DRY SLOT WILL MOVE ACROSS THE AREA
THIS MORNING...FOLLOWED BY STRONG WEST WINDS...IMPRESSIVE COLD
ADVECTION WITH FALLING TEMPERATURES IN THE AFTERNOON...AND SCATTERED
SHOWERS. THUS...UPDATE WAS MAINLY TO LOWER SKY AND POPS IN DRY SLOT
THIS MORNING.
PREVIOUS DISCUSSION...
WARM FRONTAL RAIN IN ASSOCIATION WITH POTENT STORM SYSTEM...CENTERED
OVER NW IL/EASTERN IA...CONTINUES ACROSS THE REGION THIS MORNING.
RAIN HAS BEEN HEAVY AT TIMES...WITH MANY LOCATIONS REPORTING 1 TO
1.5 INCHES OF RAIN IN THE LAST 12 HOURS. COLD FRONT ASSOCIATED WITH
THIS SYSTEM IS CURRENTLY DRAPED SOUTH FROM CENTRAL IN THROUGH
CENTRAL KY AND AREAS SOUTH...AND IS PROGGED TO MOVE INTO THE CWA
AROUND 12Z...AND EXIT AROUND 18Z. MUCH OF THE PRECIPITATION ACROSS
THE CWA APPEARS TO HAVE CHANGED TO RAIN TONIGHT DUE TO WAA AHEAD OF
THE FRONT...AND WILL PLAN TO ALLOW WINTER WEATHER ADVISORY FOR
RANDOLPH AND POCAHONTAS COUNTIES TO EXPIRE AT 4AM. STILL EXPECTING
STRONG WINDS TO DEVELOP ACROSS THE CWA TODAY AS TIGHT SURFACE
PRESSURE GRADIENT...IN COMBINATION WITH STRONG WINDS ALOFT...AFFECT
THE REGION. KRLX INDICATES WINDS IN THE FIRST FEW THOUSAND FEET
ABOVE THE SURFACE OF 50 TO 60 KTS. STRONGEST WINDS WILL OCCUR AFTER
COLD FRONT MOVES THROUGH REGION...AND WINDS ALOFT ARE ABLE TO MIX
DOWN TOWARDS THE SURFACE. ONLY MAJOR CHANGE MADE TO THE FORECAST
TODAY...WAS TO REMOVE MENTION OF THUNDER FROM THE FORECAST AS LATEST
SPC GUIDANCE INDICATES ONLY SHALLOW CONVECTION WILL BE LIKELY...AND
THAT CLOUD TOPS WILL NOT BE HIGH/COLD ENOUGH FOR CHARGE SEPARATION
TO OCCUR.
PRECIPITATION WILL GRADUALLY TAPER OFF ACROSS THE REGION TODAY AS
THE LOW CONTINUES TO MOVE OFF TO THE NORTHEAST...AND DRIER AIR WORKS
ITS WAY INTO THE REGION. COLDER AIR WILL FILTER INTO THE REGION
ON THE BACK END OF THE LOW. ANY LINGERING PRECIPITATION WILL CHANGE
TO SNOW OVERNIGHT...WITH ONLY LIGHT ACCUMULATIONS EXPECTED.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
BIG WIND MAKER PULLS AWAY FROM THE AREA TONIGHT AND THURSDAY...WITH
UPPER FLOW GOING ZONAL AS IT WEAKENS A BIT...AND HEIGHTS GRADUALLY
RISE. SFC PRESSURE GRADIENT GRADUALLY SLACKENS AS INTENSE LOW
CENTER OVER LAKE SUPERIOR THIS EVENING SHIFTS E TO THE SAINT
LAWRENCE RIVER VALLEY BY THU EVENING. UPSLOPE SNOW SHOWERS SHOULD
ALSO DIMINISH DURING THIS TIME PERIOD AS THE FLOW WEAKENS. THE WSW
DIRECTION IS NOT THE MOST FAVORABLE UPSLOPE DIRECTION SO HAVE KEPT
SNOWFALL TOTALS ACROSS THE HIGH TERRAIN UNDER THREE INCHES.
HIGH PRESSURE SAILS ACROSS THE AREA FRIDAY INTO SATURDAY...WITH
MODELS NOT INDICATING THAT THE NEXT LOW PRESSURE SYSTEM...A SOUTHERN
STREAM FEATURE...DOES NOT IMPACT THE AREA UNTIL SATURDAY NIGHT.
WITH ONLY A WEAK UPPER LEVEL SHORT WAVE TROUGH INVOLVED...AND THE
SURFACE LOW CENTER ITSELF PASSING WELL SOUTH OF THE AREA...THE
PRECIPITATION ASSOCIATED WITH THIS SYSTEM WILL BE LIGHT...AND
BOUNDARY LAYER TEMPERATURES LIKELY ABOVE FREEZING DURING THE DAY.
CONTINUED UNDERCUTTING GUIDANCE THROUGH FRI WITH THE AIR MASS COMING
IN. USED LOW LEVEL MODEL DATA TAKING ADVANTAGE OF GOOD MIXING
BELOW H925 WED NT THROUGH THU...WHEN ANOTHER SHOT OF COLD ADVECTION
TAKES PLACE. AFTER A COLDER FRI NT PER STIFF ARMING OF WEEKEND
SYSTEM...FCST GETS CLOSER TO THE NUMBERS FOR HIGHS SAT AND LOWS SAT
NT.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
A HIGH PRESSURE BUILDS IN BRINGING A VERY COLD AND DRY AIR MASS PER
NAM/SREF SHOWING H8 TEMPS IN THE MINUS 13-15C. STILL SOME GUSTY
WINDS UP TO 35 KNOTS WILL BE POSSIBLE OVER THE HIGHEST ELEVATIONS OF
OUR NORTHEAST MOUNTAINS ON FRIDAY. UNDER THESE CONDITIONS...CLEAR
SKIES WILL CONTINUE ON FRIDAY...WITH SOME CLOUDS MOVING IN FROM THE
WEST FRI NIGHT. LOWS FOR FRI NIGHT/SAT MORNING WILL RANGE FROM THE
MID 20S SOUTHERN COALFIELDS...TO THE MID TEENS NORTHEAST MOUNTAINS.
ANOTHER UPPER WAVE MOVES FROM THE SOUTHERN PLAINS...EAST AND
NORTHEAST INTO THE AREA...TO BRING A MORE SOUTHERLY FLOW INCREASING
TEMPERATURES AND HUMIDITY ON SUNDAY. KEPT SLIGHT CHANCE POPS ACROSS
THE SOUTHERN HALF OF THE AREA...SATURDAY...INCREASING TO CHANCE POPS
SAT NIGHT INTO SUNDAY. PCPN EXPECTED TO BE ALL SNOW FRI NIGHT...
CHANGING TO RAIN AND MIX SAT ACROSS THE LOWLANDS AS WARM ADVECTION
TAKES PLACE. HOWEVER...PCPN CHANGES BACK TO SNOW SAT NIGHT AREAWIDE.
DELAYED ONSET OF PCPN...BUT WENT FASTER THAN MODELS WITH LIGHT PCPN
ON SAT. STICK CLOSER TO HPC TEMPERATURES TWEAKING DOWN FEW DEGREES
LOW TEMPS THROUGH THE PERIOD.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
14Z WEDNESDAY THRU 12Z THURSDAY...
MAIN FEATURE ARE 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 55KTS CAN BE EXPECTED.
WELL DEFINED DRY SLOT WITH MAINLY CLEAR SKIES OVER THE AREA AT 14Z.
COLD FRONT WILL MOVE ACROSS THE AREA DURING THE DAY...REACHING THE
OHIO RIVER AROUND 17Z...AND EXITING THE MOUNTAINS OF WV BY 22Z. A
LINE OF RAIN SHOWERS 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 AND IN THE MOUNTAINS THIS AFTERNOON. ANY LINGERING
RAIN SHOWERS WILL BEGIN TO CHANGE OVER TO SNOW AFTER 21Z. THEN AFTER
00Z EXPECT MVFR/ISOLD IFR CONDITIONS IN SNOW SHOWERS...MAINLY IN THE
MOUNTAINS.
AFTER 12Z THURSDAY...
STRONG WINDS WILL SLOWLY DIMINISH WEDNESDAY NIGHT. BRIEF IFR
CONDITIONS WILL BE POSSIBLE IN THE MOUNTAINS AS WELL IN 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...TRM/SL
NEAR TERM...JMV
SHORT TERM...TRM
LONG TERM...ARJ
AVIATION...JMV
