FXUS61 KRNK 142047
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
347 PM EST MON DEC 14 2009

.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA TUESDAY...FOLLOWED BY DRY
HIGH PRESSURE FOR WEDNESDAY THROUGH FRIDAY.  ASIDE FOR SOME
MOUNTAIN SHOWERS...LITTLE IN THE WAY OF WETTING RAIN OR SNOW
IS EXPECTED FOR THE REMAINDER OF THIS WEEK. 

&&

.NEAR TERM /THROUGH TUESDAY/...
A RELATIVELY MILD DECEMBER NIGHT EXPECTED TONIGHT PER INFLUENCE OF
WARM TEMPERATURES ALOFT...+10 DEG AT 85H. SURFACE COLD FRONT
OVER THE OHIO VALLEY WILL APPROACH THE AREA OVERNIGHT WITH
SOUTHERLY WINDS KEEPING THINGS MIXED IN THE HIGHER ELEVATIONS.
LOWER ELEVATION MAY ONCE AGAIN DECOUPLE FOR A WIDE RANGE IN
T-MINS. FOG MAY DEVELOP IN THE VALLEY LOCATIONS AND IN THE
PIEDMONT EAST OF THE MOUNTAINS. THERE IS QUITE A BIT OF LOW 
LEVEL CLOUD COVER OVER THE CAROLINAS...AND THIS LOW LEVEL CLOUD
DECK COULD EASILY EXPAND NORTH TO ENCOMPASS AREAS EAST OF THE BLUE
RIDGE PER INCREASING SOUTHERLY FLOW AHEAD OF THE APPROACHING
FRONT. ALL THINGS CONSIDERED KEPT T-MINS PRETTY CLOSE TO
MOS...WARMEST IN THE HIGHER ELEVATIONS AND COOLEST IN THE VALLEYS.

FCST MOISTURE PROFILES INDICATE LITTLE IN THE WAY OF PRECIP THREAT
WITH TUESDAY MORNINGS FRONTAL PASSAGE......MOIST IN THE BOUNDARY
LAYER AND MOIST ABOVE 10 KFT...BUT DRY IN THE MID LEVELS. AS SUCH
WILL MAINTAIN PRETTY LOW POPS GOING INTO THE DAY TUESDAY...WITH
THE BIGGEST BY-PRODUCT FROM THIS FRONTAL PASSAGE BEING IN THE FORM
OF CLOUD COVER. THE GREATEST POPS WILL BE OVER THE WINDWARD SLOPES
WHERE THE FRONT MIGHT BE ABLE TO SQUEEZE OUT A FEW HUNDRETHS
THERE. DEEPER GULF MOISTURE LOOKS LIKE IT WILL GET SHUNTED OFF TO
OUR SOUTHEAST...LEAVING THE REST OF THE AREA DRY...NOT THAT NEED
ANYMORE AT THE MOMENT.

CLOUD COVER WILL INHIBIT A LOT OF SOLAR INSOLATION ON TUESDAY.
IF ANYTHING...COLD AIR ADVECTION WILL DEVELOP OVER THE MOUNTAINS
BEHIND THE FRONT AND MAY ACTUALLY DRAG THE TEMPERATURES DOWN. IN
THE EAST...DOWNSLOPE FLOW WILL DEVELOP BEHIND THE FRONT...SO
SHOULD SEE ONE MORE RELATIVELY MILD DAY THERE BEFORE COLD AIR
ADVECTION TURNS THE TABLE EAST OF THE MOUNTAINS.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
TUESDAY AFTERNOON AND EVENING...A NORTHERN STREAM DISTURBANCE
WILL BE TRACKING EAST FROM LAKE ERIE TO OVER THE NEW ENGLAND
REGION. TOWARDS THE SOUTH AND ALONG ALONG THE GULF STATES...A
SOUTHERN STREAM DISTURBANCE WILL TRACK ACROSS FLORIDA AND OFF THE
SOUTHEAST COAST. A WEAK COLD FRONT...ATTACHED TO THE NORTHERN
STREAM DISTURBANCE WILL MOVE FROM THE OHIO VALLEY AND OVER THE
APPALACHIAN TUESDAY...THEN JUMP SOUTH TO THE GULF/SOUTHEAST
COASTAL DISTURBANCE BY THE EVENING. WITH THE FRONT WELL THROUGH
THE AREA BY TUESDAY EVENING...COLD AIR WILL FILTER INTO THE REGION
WITH ANY LEFT-OVER RAIN SHOWERS CHANGING OVER TO SNOW/FLURRIES.
85H TEMPERATURES COLD ENOUGH TO START THE CHANGE OVER ACROSS THE
HIGHER ELEVATIONS EARLY TUESDAY EVENING. THICKNESSES BETWEEN
1000-850 MB ABOVE 1300 M FOR LOWER ELEVATIONS P-TYPE TO REMAIN AS
RAIN/DRIZZLE THROUGH THE EVENING. OVERNIGHT TUESDAY...MOISTURE
BECOMES LIMITED TO ONLY HAVE A FEW WESTERN UPSLOPE SNOW SHOWERS
ACROSS SOUTHEASTERN WEST VIRGINIA AND POSSIBLE FLURRIES TOWARDS
THE BLUE RIDGE. HIGH PRESSURE AND DRIER AIR MOVES CLOSER TO THE
AREA WEDNESDAY MORNING TO SHUT OFF THE SNOW SHOWERS AND HAVE SKIES
MOSTLY CLEAR ACROSS THE ENTIRE AREA. THIS HIGH PRESSURE WILL
INFLUENCE OUR WEATHER INTO THURSDAY.

WITH THE FRONTAL PASSAGE...BRIEF BUT STRONG PRESSURE RISES AND A 45 
KT LOW LEVEL JET WILL BRING WINDY CONDITIONS TO THE MOUNTAINS TUESDAY 
NIGHT. HIGHER ELEVATIONS ABOVE 3000 FEET COULD SEE ADVISORY CRITERIA 
FOR GUSTS BUT NOT ENOUGH COVERAGE AT THIS TIME FOR A HEADLINE. 
LIGHTER WINDS BUT STILL BREEZY CONDITIONS EXPECTED FOR WEDNESDAY. 

DESPITE COLD AIR MOVING OVER THE REGION...OVERNIGHT MIXING SHOULD 
KEEP TEMPERATURES ABOVE NORMAL TUESDAY NIGHT. STILL LOOKING AT A 
COLD NIGHT WITH MOUNTAIN TEMPERATURES IN THE MID TO UPPER 20S AND 
30F TO 35F EAST. WITH THE WIND BLOWING...YOU CAN KNOCK OFF ABOUT 5F 
FOR THE APPARENT TEMPERATURES WEDNESDAY MORNING. CHILLY BUT NEAR 
NORMAL TEMPERATURES EXPECTED WEDNESDAY FOR THE EAST...WHILE THE 
MOUNTAINS REMAIN IN THE 30S. WITH MORE INFLUENCE FROM THE SURFACE 
RIDGE WEDNESDAY NIGHT...RADIATIONAL COOLING WILL HAVE TEMPERATURES 
DROPPING BELOW NORMAL. A WARM FRONT WILL HAVE TEMPERATURES 
MODERATING ABOVE NORMAL THURSDAY AND THURSDAY NIGHT.
&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
THE UPPER LEVEL FLOW WILL SLOWLY AMPLIFY OVER THE WEEKEND. 
DRY INITIALLY...WILL HAVE TO MONITOR CLOSELY FOR SURFACE LOW
PRESSURE DEVELOPMENT ALONG THE SOUTHEAST COAST. ON SATURDAY...
SURFACE RIDGE IS STILL HANGING ACROSS THE COUNTY WARNING AREA.
THIS WILL RESULT IN CONTINUING DRY WEATHER THROUGH THE EARLY PART
OF THE WEEKEND. AS THE SURFACE HIGH PUSHES NORTHEAST...UPPER LEVEL
TROUGHING WILL MOVE OVERHEAD BY LATE SATURDAY.

A SURFACE LOW IS EXPECTED TO DEVELOP OVER THE GULF OF MEXICO AND 
SLIDE EAST ACROSS FLORIDA AND OVER THE ATLANTIC. BOTH THE GFS AND 
ECMWF SHOW THIS LOW PRESSURE SYSTEM MOVING FAR EAST ACROSS THE 
ATLANTIC WHILE A SECONDARY LOW DEVELOPS ON A WAVE ALONG THE 
SOUTHEAST COAST. THIS LOW WILL DEEPEN AS IT RIDES NORTHEAST 
WITH THE GFS INDICATING A STRONGER AND DEEPER LOW THAN THE ECMWF. 
THERE ARE STILL UNCERTAINTIES BEING IN THE EXTENDED WITH THE ECMWF 
CONTINUING TO BE SLOWER THAN THE GFS. 

COLD AIR ADVECTION FILTERS IN BY THE END OF THE WEEK AND GETS 
STRONGER BY LATE WEEKEND. IF THE TREND KEEPS UP...THE TEMPERATURES 
WILL DEFINITELY BE COLD ENOUGH FOR SNOW BUT THE QUESTION OF HOW MUCH 
MOISTURE WILL BE IN PLACE STILL REMAINS A MYSTERY. THE LATEST RUN OF 
THE ECMWF SHOWS MUCH LESS PRECIP THAN THE PREVIOUS RUN WHICH MATCHES 
MORE WITH THE GFS. AT THIS TIME...ONLY HAVE SLIGHT CHANCE POPS GOING 
FROM WEST TO EAST THROUGH SUNDAY NIGHT BEFORE TAPERING OFF IN THE 
EAST. WITH THE NORTHWESTERLY FLOW...LINGERING SNOW SHOWERS WILL 
IMPACT THE FAVORABLE UPSLOPE REGIONS OF THE FORECAST AREA.

TEMPERATURES WILL CONTINUE COOLING THROUGH THE WEEKEND WITH THE 
MOUNTAINS LOWERING INTO THE UPPER 30S...WHILE THE PIEDMONT WILL DROP 
INTO THE MID 40S BY SUNDAY. MIN TEMPS WILL FALL IN THE RANGE FROM 
UPPER TO LOWER 20S ACROSS THE BOARD. 

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
MAINLY VFR CONDITIONS THIS AFTERNOON. THERE IS A LAYER OF
CLOUDINESS THAT WILL DRIFT NORTH FROM THE CAROLINAS WITH CLOUD
BASES BETWEEN 025 AND 040 KFT AGL. AS SUCH TEMPO MVFR CONDITIONS
MAY BE OBSERVED ALONG AND EAST OF THE BLUE RIDGE...BUT FOR THE
SAKE OF SIMPLICITY KEPT CONDITIONS PREDOMINANTLY VFR WITH NO
TEMPO GROUPS.

FOR TONIGHT...THE TREND WILL LIKELY BE DOWN...WITH LOWERING CLOUD
BASES AHEAD OF AN APPROACHING COLD FRONT. SOME FOG IS
POSSIBLE...ESP EAST OF THE BLUE RIDGE...WHERE IFR CONDITIONS ARE
POSSIBLE...PERSISTING UNTIL THE FRONTAL PASSAGE EARLY TUESDAY MORNING.

A COLD FRONT WILL MOVE THROUGH THE REGION EARLY TUESDAY...BRINGING
A LOW THREAT OF PRECIPITATION AND MVFR TO IFR CONDITIONS IN THE
MOUNTAINS. ONCE THE FRONT PUSHES EAST OF THE MOUNTAINS...STRONG
DOWNSLOPE FLOW SHOULD DEVELOP WHICH SHOULD SCOUR ANY LOW
CLOUDINESS EAST OF THE MOUNTAIN. ALONG THE WINDWARD
SLOPES...CLOUDS WILL PERSIST...WITH STRONG COLD ADVECTION
RESULTING IN MOUNTAIN RAIN/SNOW SHOWERS.

COLD HIGH PRESSURE WILL BUILD OVER THE AREA TUESDAY NIGHT AND
WEDNESDAY WITH UNRESTRICTED FLIGHT CONDITIONS. AN UPPER LEVEL
DISTURBANCE WILL MOVE THROUGH THE OHIO VALLEY THURSDAY INTO FRIDAY
SPREADING CLOUDINESS BACK INTO THE MOUNTAINS WITH THE THREAT OF
SNOW SHOWERS.

&&

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

&&

$$
SYNOPSIS...PM
NEAR TERM...PM
SHORT TERM...RCS
LONG TERM...REB
AVIATION...PM