FXUS61 KRNK 302047
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
347 PM EST MON NOV 30 2009
.SYNOPSIS...
A COLD FRONT WILL MOVE OFFSHORE THIS EVENING. ANOTHER STRONG LOW
PRESSURE SYSTEM ALONG THE GULF COAST LIFTS NORTH ALONG THE
APPALACHIANS WEDNESDAY INTO WEDNESDAY NIGHT...DELIVERING MUCH COLDER AIR
FOR THE END OF THE WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
SHORT WAVE MOVING INTO NORTHERN VIRGINIA AND ASSOCIATED COLD FRONT
AND AREA OF RAINFALL WILL BE EAST OF THE FORECAST AREA JUST AFTER
00Z. WINDS WILL BE GUSTY OUT OF THE NORTHWEST BEHIND THE
FRONT...ESPECIALLY IN THE NORTHERN COUNTY WARNING AREA AROUND 12Z ON
TUESDAY. MOST OF THE GUIDANCE KEPT THE 850 WINDS AOB 40 KNOTS SO
WILL HOLD OFF ON ANY ADVISORY FOR NOW.
MOISTURE IN THE UPSLOPE AREAS THIS EVENING BECOMES VERY SHALLOW BY
06Z. NOT LONG ENOUGH DURATION OF ANY SNOWFALL FOR MORE THAN AN INCH
OF SNOW IN SOUTHEAST WEST VIRGINIA.
850 MB TEMPERATURES AROUND -4 TO -6 DROP INTO THE WESTERN COUNTY
WARNING AREA OVERNIGHT BUT BY 12Z TUESDAY COLDER AIRMASS IS ALREADY
PULLING NORTHEAST OUT OF THE AREA. NOT MUCH SPREAD IN THE GUIDANCE
FOR LOWS TONIGHT. STAYED ON THE COOL SIDE OF MAV/MET NUMBERS IN MOST
LOCATIONS. WITH LOTS OF SUNSHINE ON TUESDAY HIGH TEMPERATURES WILL
BE BACK AROUND NORMAL.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
RAIN WILL BREAK OUT ON WEDNESDAY ACROSS THE CWA AS A STRONG AREA
OF LOW PRESSURE MOVES JUST WEST OF THE APPLN MTNS. THE OP
GFS/GEFS/ECMWF WERE FOLLOWED AS OPPOSED TO THE NAM...ALTHOUGH THE
18Z NAM HAS A MORE REASONABLE TRACK. H85 WINDS FROM THE GFS GET TO
75KTS JUST WEST OF A BLF/JFZ LINE WED PM...AND SOME TYPE OF WIND
HEADLINE WILL LIKELY BE NEEDED AS THE EVENT NEARS ACROSS THE WEST.
WITH A MOIST AND A NEARLY STABLE SOUNDING IN THE LLVLS...MIGHT BE
DIFFICULT TO GET HIGH WIND CRITERIA...ALTHOUGH SOME TREES MAY
TOPPLE WITH HVY RAIN. WILL HOLD OFF ANY HEADLINES FOR NOW
CONSIDERING MUCH OF THIS EVENT WILL OCCUR IN THE FOURTH PERIOD.
CONCERNED ABOUT CONVECTION ACROSS THE SE LIMITING QPF THIS FAR
NORTH...BUT WITH NEARLY EVERY MODEL ON BOARD...DID INC QPF FOR
THIS EVENT...BUT NOT QUITE AS HIGH AS HPC FOR THE TIME BEING. COLD
AIR AND DOWNSLOPING WIND BUILD IN QUICKLY INTO THURS MORNING...AND
REDUCED POPS QUICKER THAN PREVIOUS FORECAST...REMOVING THE HIGH
POPS EAST OF THE BLUE RIDGE THROUGH WED AFTERNOON. NOT THE BEST
UPSLOPE COMPONENT FOR SE WEST VA AND SW VA ON THURSDAY...BUT SOME
LIGHT ACCUMS ARE POSSIBLE THURSDAY ABV 3K FEET.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
ON FRIDAY...AN UPPER LEVEL LOW WILL BE IN THE VICINITY OF THE GREAT
LAKES WITH THE FLOW OVER THE SOUTHERN APPALACHIANS BEING
WEST-NORTHWEST. THIS PATTERN WILL NOT CHANGE MUCH THROUGH FRIDAY
NIGHT. THEREFORE...CONTINUED BROKEN STRATOCUMULUS CLOUDS WITH OFF
AND ON AGAIN LIGHT MOUNTAIN SNOW SHOWERS/FLURRIES. ANY ACCUMULATION
WILL BE CONFIDED TO EXTREME WESTERN SLOPES OF SOUTHEASTERN WEST
VIRGINIA. EAST OF THE BLUE RIDGE...WILL SEE MOSTLY SUNNY SKIES
BROUGHT TO YOU BY DOWNSLOPING WESTERLY WINDS. SNOW SHOWERS WILL END
AND SKIES WILL CLEAR ACROSS THE AREA THROUGH EARLY NEXT WEEK. WITH
HIGH PRESSURE OVER THE AREA AND ZONAL FLOW ALOFT...NO PRECIPITATION
IS EXPECTED UNTIL THE MIDDLE OF NEXT WEEK.
DID NOT CHANGE MUCH IN THE EXTENDED FORECAST WITH THE EXCEPTION OF
RAISING POPS FRIDAY ALONG WESTERN SLOPES AND EXTENDING THEM DEEPER
INTO FRIDAY NIGHT.
TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH THE WEEKEND WITH THE
TROUGH REMAINING TO THE WEST FRIDAY NIGHT FOLLOWED BY A CHILLY
SURFACE HIGH OVER THE WEEKEND. TEMPERATURES ARE EXPECTED TO REBOUND
EARLY NEXT WEEK WITH A PASSING OF A WARM FRONT.
THE 12Z GFS SHOWING A WAVE ROUNDING THE TROUGH IN THE SOUTHERN
PLAINS...GRABBING SOME GULF MOISTURE...THEN PRODUCING SNOW IN OUR
NECK OF THE WOODS FRIDAY NIGHT AND SATURDAY. THE 12Z GFS WAS THE
ONLY MODEL SHOWING THIS LIGHT SNOW EVENT. SURFACE FLOW REMAINS OUT
OF THE WEST-NORTHWEST...LOW LEVEL FLOW IS WESTERLY AND UPPER LEVEL
FLOW IS SOUTHWESTERLY. THE COLD FRONTAL BOUNDARY FROM WEDNESDAY
NIGHT RAIN EVENT WILL BE ALONG THE SOUTHERN TIP OF FLORIDA. GIVEN
THIS PATTERN...A MID LEVEL WAVE COULD RIDE OVER THE AREA BUT
MOISTURE SHOULD ONLY CREATE OVERCAST SKIES TO POSSIBLE FLURRIES. THE
GFS IS PRODUCING A TENTH TO A QUARTER INCH OF LIQUID PRECIP...WHICH
IS WAY OVER DONE. LIKING THE ECMWF WITH SHORT WAVES ROUNDING THE
TROUGH...BUT KEEPING BULK OF PRECIPITATION OVER FLORIDA.
&&
.AVIATION /21Z MONDAY THROUGH SATURDAY/...
A COLD FRONT WILL CROSS QUICKLY EAST THROUGH THE FORECAST AREA
THIS AFTERNOON. AT THE BEGINNING OF THE TAF PERIOD THE FRONT WILL
BE JUST EAST OF BLF AND LWB...AND BY 22Z WILL BE GOING THROUGH
DAN. DEEP MOISTURE CLEARS OUT RAPIDLY BEHIND THE FRONT WITH CLOUDS
STARTING TO BECOME SCATTERED EAST OF THE BLUE RIDGE BY 00Z.
ROA...LYH...AND DAN WILL BECOME VFR BY 03Z AND WILL REMAIN VFR FOR
THE REST OF THE FORECAST PERIOD.
COLD AIR ADVECTION AND LOW LEVEL MOISTURE WILL HOLD THE CLOUDS IN
LONGER AT LWB WHERE CLEARING IS NOT EXPECTED UNTIL AFTER 06Z.
LIGHT SNOW SHOWERS ARE ALSO POSSIBLE AT BLF AND LWB AFTER 21Z
TODAY AS COLD AIR SURGES INTO THE REGION. ANY SNOWFALL AMOUNTS
WILL BE LIGHT WITH OCCASIONAL MVFR CEILINGS AND VISIBILITIES.
WINDS WILL ALSO BE GUSTY BEHIND THE FRONT TONIGHT BUT WILL
DIMINISH ON TUESDAY AS HIGH PRESSURE BUILDS INTO THE AREA.
ANOTHER STORM SYSTEM WILL BRING A GOOD CHANCE FOR SIGNIFICANT
RAIN BY WEDNESDAY AFTERNOON...WITH WIDESPREAD IFR CONDITIONS...POSSIBLY
CONTINUING THROUGH THURSDAY. UPSLOPE SNOW SHOWERS LOOK TO LINGER
MVFR CONDITIONS ACROSS SE WVA INTO FRIDAY WITH VFR ELSEWHERE.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/KM
NEAR TERM...AMS
SHORT TERM...KM
LONG TERM...RCS
AVIATION...AMS/JH
