FXUS61 KRNK 071552
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1052 AM EST MON DEC 7 2009

.SYNOPSIS...
HIGH PRESSURE WILL HEAD EAST OFF THE ATLANTIC COAST AS A WEAK
DISTURBANCE MOVES THROUGH THE OHIO VALLEY TONIGHT INTO TUESDAY. A
STRONG AREA OF LOW PRESSURE WILL MOVE THROUGH THE GREAT LAKES
REGION ON WEDNESDAY...BRINGING A COMPLEX SERIES OF FRONTS THROUGH
OUR REGION. HIGH PRESSURE WILL RETURN NEXT WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE OVER THE ERN HALF OF VA/NC WILL SLIDE EAST THIS
AFTERNOON. A SW FLOW WILL INCREASE SOME ALLOWING FOR TEMPS TO RISE
A LITTLE HIGHER THAN YESTERDAY OVER THE SNOW COVERED WEST AND
NORTH WITH MELTING EXPECTED. HOWEVER...THIS HIGH WILL KEEP EASTERN
TEMPERATURES COOL THIS AFTERNOON AS WINDS WILL REMAIN LIGHT AND VARIABLE.

WEAK TROUGH MOVING ACROSS THE CENTRAL APPS THIS MORNING WITH LIGHT
RAIN/SNOW WILL DRY UP AS IT MOVES INTO THE FORECAST AREA. 

THEN...A WEAK SURFACE BOUNDARY WILL APPROACH THE WESTERN SLOPES MONDAY
EVENING. MOISTURE IS LIMITED...BUT A FEW LIGHT RAIN
SHOWERS/SPRINKLES/FLURRIES COULD FALL ACROSS THE GREENBRIER VALLEY
INTO THE ALLEGHANY HIGHLANDS MONDAY EVENING. THIS BOUNDARY WILL
FALL APART CROSSING THE MOUNTAINS...BUT A LIGHT WEST WIND WILL
DEVELOP. THIS WESTERLY FLOW WILL BANK CLOUDS UP AGAINST WESTERN
SLOPES OVERNIGHT WHILE CLEARING TAKES PLACE EAST OF THE BLUE
RIDGE. WITH EVENING CLEARING...TEMPERATURES WILL BE ALLOW TO
RADIATE DOWN INTO THE LOWER 30S ACROSS MOST OF THE AREA...UPPER
20S POSSIBLE IN HIGHER ELEVATIONS AND MOUNTAIN VALLEYS HANGING ON
TO SNOW PACK. HIGH PRESSURE BEHIND THE WEAK SURFACE BOUNDARY
MONDAY NIGHT WILL MOVE FROM THE OHIO VALLEY AND OVER THE MID
ATLANTIC REGION. THIS RIDGE WILL WEDGE DOWN THE EAST COAST EARLY
TUESDAY MORNING AND SET THE STAGE FOR THE NEXT EVENT.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
STRONG LOW PRESSURE SYSTEM WILL TRACK FROM THE CENTRAL PLAINS INTO 
THE GREAT LAKES. LEANED TOWARD THE FASTER TIMING OF THE GFS ON 
TUESDAY AND WEDNESDAY. LOW LEVEL WINDS COME AROUND TO THE SOUTH BY 
TUESDAY MORNING THEN INCREASE SIGNIFICANTLY ON TUESDAY NIGHT AND 
WEDNESDAY. WILL HIGHLIGHT POTENTIAL FOR ADVISORY LEVEL WINDS IN THE 
SOUTHWEST COUNTIES OF THE FORECAST AREA TUESDAY NIGHT. 

HAVE RAISED THE PROBABILITY OF PRECIPITATION ON TUESDAY AFTERNOON 
AND TUESDAY NIGHT. EXPECT A WEDGE TO BE IN PLACE BY TUESDAY MORNING. 
WILL BE STARTING WITH HIGH CLOUDS AND CEILINGS WILL LOWER THROUGHOUT 
THE DAY SO HAVE LOWERED HIGH TEMPERATURES ON TUESDAY. WARM FRONT 
PUSHES NORTH AND ERODES THE WEDGE EARLY WEDNESDAY MORNING JUST 
BEFORE THE COLD FRONT COMES THROUGH. THIS WILL RESULT IN RISING 
OVERNIGHT TEMPERATURES IN THE SOUTHERN AND WESTERN COUNTY WARNING 
AREA. BUFKIT SOUNDING ARE SHOWING THE PRECIPITATION IN NORTHERN 
GREENBRIER AND BATH COUNTIES MAY START AS SLEET THEN CHANGE TO 
FREEZING RAIN AS THE AIR ABOVE THE CAD WARMS UP WELL ABOVE +3 DEG. 

WINDS WILL STILL BE GUSTY OUT OF THE SOUTHWEST TO WEST ON WEDNESDAY 
NIGHT AS COLD AIR SURGES INTO THE AREA. IN ADDITION TO THE COLD AIR 
ADVECTION STRONG PRESSURE RISES ARE FORECAST. BY WEDNESDAY EVENING 
THE PRECIPITATION WILL TRANSITION TO UPSLOPE SHOWERS...WHICH SHOULD 
BE ALL SNOW BY LATE WEDNESDAY NIGHT.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE UPPER PATTERN NEXT WEEK WILL BE DOMINATED BY AN OMEGA BLOCK OVER 
ALASKA...AND A VERY STRONG POLAR VORTEX SPINNING THROUGH EXTREME NW 
CANADA. TYPICALLY THIS SETUP DOES NOT MERIT COLD AIR DELIVERY INTO 
THE MIDDLE ATLANTIC. HOWEVER...A PIECE OF THIS GYRE WILL BREAK OFF 
AND FORM A RATHER STRONG UPPER LOW SOUTH OF HUDSON BAY. DESPITE THE 
LACK OF ANY HIGH LATITUDE BLOCKING ACROSS GREENLAND...THIS SECOND 
UPPER LOW WILL BE ENOUGH TO ALLOW COLDER AIR TO SPILL INTO THE CWA 
LATE NEXT WEEK AND INTO NEXT WEEKEND. STILL POSSIBLE THAT PERHAPS 
H85 PROGGED TEMPS WARM SOMEWHAT...AND THIS WILL BE IMPORTANT 
CONSIDERING AN AREA OF LOW PRESSURE MOVING ALONG THE SOUTHEAST COAST 
PER THE 0Z ECMWF AND THE 12Z GFS NEXT SATURDAY. THIS SYSTEM WILL BE 
THE BEST OPPORTUNITY FOR PRECIP THROUGH THE LONG TERM FORECAST. 
EXPECTING MAX TEMPS AROUND 40S ELEVATIONS AND MID UPPER 40S 
PIEDMONT/SOUTHSIDE.

&&

.AVIATION /16Z MONDAY THROUGH FRIDAY/...
SOUTHWEST FLOW ALOFT BRINGING IN SOME MILDER AIR ACROSS THE
MOUNTAINS. AS THIS AIR MOVES OVER RESIDUAL SNOW PACK...PATCHY FOG
WILL DEVELOP...ESPECIALLY IN VALLEYS. ANY FOG THAT DOES DEVELOP
WILL BURN OFF QUICKLY THIS MORNING. 

ONE HIGH PRESSURE SYSTEMS EXITS WHILE ANOTHER TRACKS FROM THE
OHIO VALLEY AND OVER THE MID ATLANTIC REGION MONDAY NIGHT. AS THIS
SECOND HIGH WEDGES DOWN THE EAST COAST...A DISTURBANCE WILL MOVE
OUT OF THE GULF. THESE TWO SYSTEMS WILL INTERSECT OVER THE AREA
BEGIN TUESDAY AFTERNOON. THIS DISTURBANCE WILL BRING RAIN AND IFR
OR LOWER RESTRICTIONS TO THE AREA INTO WEDNESDAY MORNING.
TEMPERATURE PROFILES LOOKING WARM ENOUGH TO HAVE THE WHOLE EVENT
AS RAIN...BUT POCKETS OF FREEZING RAIN ARE POSSIBLE...ESPECIALLY
OVER THE GREENBRIER AND ALLEGHANY HIGHLAND VALLEYS. WIND/WIND
SHEAR WILL BE PROBLEMATIC AS SOUTHWEST LOW LEVEL JET IN THE RANGE
OF 60-70 KTS IS POSSIBLE TUESDAY NIGHT. THESE STRONGER WINDS WILL
REMAIN ALOFT AS SURFACE WEDGE IS DRAPED ACROSS THE AREA.

THE SYSTEM AND ASSOCIATED RAIN WILL MOVE OUT OF THE AREA BY WEDNESDAY 
AFTERNOON. TIGHTENING PRESSURE GRADIENT AND WESTERLY WINDS WILL 
INCREASE ACROSS THE REGION. WINDY AND GUSTY CONDITIONS POSSIBLE INTO 
THURSDAY NIGHT.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.

&&

$$
SYNOPSIS...RCS
NEAR TERM...RCS/WP
SHORT TERM...AMS
LONG TERM...KM
AVIATION...RCS