FXUS61 KRNK 070942
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
442 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/...
COLD HIGH PRESSURE...CENTERED OVER THE AREA THIS MORNING...WILL
SLIDE OFF THE VA COAST THIS AFTERNOON. THIS HIGH WILL KEEP EASTERN
TEMPERATURES COOL TODAY AS WINDS WILL REMAIN LIGHT AND VARIABLE.
FARTHER TO THE WEST...THE EAST COAST HIGH WILL BEGIN TO LOSE ITS
AFFECT WITH A SOUTHERLY FLOW DEVELOPING. WITH TEMPERATURES BEING
ALLOWED TO WARM IN THE WEST AND REMAIN COOL IN THE EAST...UNIFORM
HIGHS IN THE 40S ARE EXPECTED. RESIDUAL SNOW PACK COULD OFF SET
WARMING IN THE WEST AND SOME SITES MAY ONLY REACH THE UPPER 30S.
THIS WILL BE MORE EVIDENT IN THE HIGHER ELEVATIONS.
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 /10Z MONDAY THROUGH FRIDAY/...
THERE IS THE POTENTIAL FOR SOME PATCHY FOG TO DEVELOP NEAR OR
SOUTH OF KBLF EITHER LATE TONIGHT OR EARLY MONDAY AS SW WINDS
START TO INCREASE AND ALLOW FOR AN INC IN LLVL MOISTURE. AT THIS TIME
CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE ANY REDUCED VSBYS AT
KBLF.
PATCHY MVFR CONDITIONS POSSIBLE MONDAY NIGHT INTO TUESDAY IN THE
MOUNTAINS WITH A PASSING COLD FRONT.
WINTRY MIX OF PRECIPITATION POSSIBLE OVER WESTERN AND NORTHERN
PARTS OF THE AREA TUESDAY NIGHT INTO WEDNESDAY AS AN EXPANSIVE
STORM SYSTEM MOVES THROUGH BOTH THE OHIO VALLEY AND CENTRAL AND
SOUTHERN APPALACHIANS. VERY STRONG WINDS WILL ALSO ACCOMPANY THIS
SYSTEM AND PRODUCE A MIX OF STRONG SURFACE GUSTS IN THE MOUNTAINS
WITH THE POTENTIAL FOR LOW LEVEL WIND SHEAR EAST OF THE BLUE RIDGE.
A TIGHT PRESSURE GRADIENT BEHIND THE SYSTEM WILL ALLOW GUSTY
CONDITIONS AND THE POTENTIAL FOR LOW LEVEL WIND SHEAR TO CONTINUE
INTO FRIDAY. THERE MAY EVEN BE SOME LINGERING UPSLOPE SE WV
SCATTERED SNOW SHOWERS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...RCS
NEAR TERM...RCS
SHORT TERM...AMS
LONG TERM...KM
AVIATION...DS/KM
