000
FXUS61 KRNK 200505
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1205 AM EST THU NOV 20 2008
.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO SHIFT SOUTH OF THE AREA TONIGHT
AHEAD OF ANOTHER COLD FRONT APPROACHING FROM THE NORTHWEST. THIS
FRONT WILL PASS THROUGH THE REGION THURSDAY. COLDER AIR ARRIVES
THURSDAY NIGHT AND FRIDAY WITH ADDITIONAL MOUNTAIN SNOW SHOWERS
LIKELY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
CLIPPER WILL RACE ACROSS THE GREAT LAKES OVERNIGHT AND BY MORNING
MAY HAVE SOME INFLUENCE ACROSS WESTERN SLOPES OF SOUTHEASTERN WEST
VIRGINIA. WITH MOISTURE THIS EVENING BEING CONFIDED BETWEEN
7-9KFT...4-6KFT IN SE WV...NOT EXPECTING ANY THING TO FALL UNTIL
AROUND SUNRISE. AND IF ANY PRECIPITATION DOES FALL TOWARDS MORNING...IT
WILL LIKE BE ALONG WESTERN SLOPES/HIGHER ELEVATIONS OF GREENBRIER.
AMOUNTS MAY BE HARD PRESSED TO MEASURE SO WILL LEAVE CURRENT LOW
POPS AS IS. FLOW DOES BACK TO THE SOUTHWEST OVERNIGHT AND WITH
INCOMING WARM AIR ADVECTION...I ADDED FLURRIES TO OTHER WESTERN SLOPES
TOWARDS MORNING...NAMELY THE BLUEFIELD AREA.
STILL A FAIR AMOUNT OF CLOUDS OVER THE NORTHERN HALF OF THE CWA
(LWB-RNK-DAN) WITH SOME CLEARING TO THE SOUTH. THIS CLEARING TREND
SHOULD PERSIST THROUGH THE NIGHT WITH THE EXCEPTION OF THE GREENBRIER
VALLEY AND ALLEGHANY HIGHLANDS. CLOUDS TO REAPPEAR ALONG WESTERN
SLOPES AROUND SUNRISE AS WARM AIR NOSES IN AHEAD OF THE CLIPPER.
THIS WARM AIR MAY KEEP RIDGES WARMER THAN THE VALLEYS AND EAST
OVERNIGHT. HOWEVER...CLEAR SKIES...LIGHT WINDS AND SNOW ON THE
GROUND MAY OFF SET THE WARM AIR ADVECTION. NEVER THE
LESS...TEMPERATURES WILL BE COLD AND ABOUT 10F TO 15F BELOW NORMAL.
WITH INVERSION REMAINING THROUGH THE OVERNIGHT HOURS...INCREASING
LOW LEVEL JET SHOULD NOT MIX DOWN UNTIL MID MORNING THURSDAY. WINDS
WILL BECOME BREEZY/GUSTY DURING THE DAY THURSDAY.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/...
COLD FRONT WILL BE CROSSING THE AREA FROM THE WEST EARLY THU WITH
SUBSEQUENT COLD AIR ADVECTION GRADUALLY SPILLING IN FROM THE WEST IN
THE AFTERNOON. MOISTURE INITIALLY REMAINS RATHER LIMITED
ALONG/BEHIND THE FRONT IN WESTERLY FLOW REGIME AND LAGGING DEEP COLD
AIR. HOWEVER EXPECT MAY SEE A BAND OF SNOW/RAIN SHOWERS JUST AHEAD
OF THE ONSET OF THE BETTER 85H COLD ADVECTION IN THE AFTERNOON.
SINCE QPF WITH THIS APPEARS RATHER LIGHT AND SPOTTY...REDUCING POPS
SOME UNTIL LATE WHEN WILL KEEP LOW LIKELYS NW WHICH MIGHT BE
GENEROUS. OTRW LOW CHANCE POPS ACROSS THE UPSLOPE REGION WITH
DOWNSLOPE PC TO MOSTLY SUNNY PIEDMONT. HIGHS SHOULD SEE A RANGE FROM
LOW 50S SE TO MID/UPPER 30S SE WVA WHERE BEST COLD AIR ALOFT WILL
ARRIVE SOONER.
BETTER SURGE OF REAL COLD AIR ARRIVES THU NIGHT AND CONTINUES THRU
FRIDAY AS NEXT S/W SLIDES IN FROM THE WEST WITH THE UPPER TROF.
FORECAST SOUNDINGS SUGGEST UPSLOPE RH WILL DEEPEN ENOUGH FOR AREAS OF
-SHSN WEST...LEADING TO MORE SUBSTANTIAL BANDING LATE AS VORT
PASSES. HOWEVER BEST NW FLOW LAKE TRAJECTORY WONT DEVELOP UNTIL
LATER THU NIGHT/FRIDAY MORNING WHICH MAY COINCIDE WITH LESSENING LOW
LEVEL MOISTURE. THIS IN COMBO WITH LESS DIGGING NATURE TO THE UPPER
SYSTEM SUGGESTS TOTALS OUTSIDE OF THE HIGHEST PEAKS MAY STAY BELOW
WARNING CRITERIA WRN GREENBRIER CTY...WITH 1-3 INCHES ELSW INCLUDING
SOUTH INTO THE NW NC MTNS. SINCE CONFIDENCE TOO LOW WITH THIS EVENT
AS COMPARED TO THE LAST WONT POST AN ELEVATION WATCH AT THIS POINT
AND KEEP THE HWO MENTION OF ADVISORY LEVEL SNOWFALL FOR NOW. OTRW
POPS RANGING FROM LIKELY/CAT UPSLOPE AREAS TO CHANCEY EAST TO THE
BLUE RIDGE AND MAINLY PC/DRY EAST. WILL ALSO TURN MUCH COLDER AGAIN THU
NIGHT WITH THE ARRIVAL OF -12C 85H TEMPS...AND THEN WINDY/VERY COLD
MOUNTAINS FRIDAY WHERE HIGHS WILL LIKELY ONLY REACH THE MID/UPPER
20S.
UPSLOPE MOISTURE SHOULD DIMINISH FRIDAY EVENING AND GIVE WAY TO
CLEARING SKIES THRU SAT IN RESPONSE TO COLD HIGH PRESSURE BUILDING
IN FROM THE WEST. WILL HAVE SOME RESIDUAL FLURRIES EXTREME NW FRIDAY
EVENING OTRW CLEARING BUT BITTERLY COLD FRIDAY NIGHT WEST OVER SNOW
COVER AND UNDER LESS WIND. AGAIN LOOKS LIKE SOME SINGLE DIGITS IN THE
VALLEYS AND TEENS TO LOW 20S ACROSS THE PIEDMONT. HIGH BUILDS
OVERHEAD SATURDAY ALLOWING SOME SLOW TEMP RECOVERY UNDER SUNSHINE
BUT STILL LOW/MID 30S WEST TO MID 40S EAST. MAINLY CLEAR ALTHO STILL
VERY COLD SAT NIGHT WITH MORE TEENS/20S GIVEN THE RIDGE LINGERING
ABOUT OVERHEAD.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
BRIEF SPELL OF S/W RIDGING AND WARMING SUNDAY WILL GIVE WAY TO YET
ANOTHER 5H TROF AND ITS ASSOCIATED COLD FRONT LATER MONDAY. LOOKS
LIKE ENOUGH WARM ADVECTION UNDER INSOLATION TO PERHAPS PUSH ALL
AREAS INTO THE 40S WITH SOME 50S EAST SUNDAY...EXCEPT OVER THE NW
SNOW COVER WHERE 30S LIKELY TO LINGER. FRONT SLIDES THRU MONDAY
NIGHT PER THE SLOWER ECMWF WITH A ROUND OF RAIN SHOWERS THAT MAY
SWITCH TO SNOW SHOWERS MOUNTAINS BEFORE TRENDING TOWARD ANOTHER
ROUND OF UPSLOPE -SHSN LATER MONDAY NIGHT/TUESDAY. THUS WILL CARRY
CHANCE POPS MONDAY INTO MONDAY NIGHT...THEN MAINLY WESTERN ZONES
TUESDAY AS MORE S/W ENERGY ROUNDS THRU THE TROF AND ACROSS THE
REGION. SHOULD START TO SEE MORE DRYING WED AS THE 5H TROF STARTS
TO LIFT OUT AGAIN SO LOW POPS MAINLY FAR WESTERN ZONES FOR THE
MOST PART. HIGH TEMPS REMAIN MILD AS COMPARED TO LATE WITH THE
FROPA MONDAY...THEN SLOWLY COOL UNDER THE NEXT SHOT OF COLD
ADVECTION THRU WED...BRINGING HIGHS BACK INTO THE 30S/LOW 40S WEST
TO MID/UPPER 40S EAST OF THE BLUE RIDGE.
&&
.AVIATION /05Z THURSDAY THROUGH MONDAY/...
A COLD FRONT WILL CROSS THROUGH THE FORECAST AREA ON THURSDAY.
CEILINGS WILL LOWER TO MVFR ALONG AND BEHIND THE
FRONT...ESPECIALLY IN THE MOUNTAINS. UPSLOPE SNOW SHOWERS AND
SCATTERED FLURRIES ARE ALSO EXPECTED BUT VISIBILITIES MAY VARY
BETWEEN VFR AND MVFR AT BLF AND LWB.
AREAS EAST OF THE BLUE RIDGE SHOULD AGAIN REMAIN UNRESTRICTED DUE
TO DOWNSLOPE DRYING. HOWEVER...SFC WINDS THURSDAY AFTERNOON AND
EVENING BEHIND THE FRONT WILL INCREASE TO 10 TO 20 KNOTS WITH HIGHER
GUSTS.
LOW LEVEL WIND SHEAR COULD BE PROBLEMATIC BETWEEN 06Z AND 12Z AS 850
MB JET INCREASES TO AROUND 40KTS WHILE SURFACE WINDS REMAIN LIGHT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/KK/WP
NEAR TERM...RCS
SHORT TERM...JH
LONG TERM...JH
AVIATION...KM/RCS
