FXUS61 KRNK 260144
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
844 PM EST FRI DEC 25 2009

.SYNOPSIS...
HIGH PRESSURE REMAINS WEDGED DOWN THE EAST SIDE OF THE
APPALACHIANS. WEAK LOW PRESSURE DEVELOPING IN THE NORTH CAROLINA
PIEDMONT WILL TRACK INTO EASTERN VIRGINIA BY SATURDAY MORNING.
COLDER HIGH PRESSURE WILL SLOWLY BUILD INTO THE REGION OVER THE
WEEKEND.

&&

.NEAR TERM /THROUGH SATURDAY/...
RADAR SHOWING ONLY LIGHT RETURNS AND WILL CUT POPS BACK QUICKER
FROM THE SOUTH...WITH MODEL SOUNDINGS DEPICTING FOG/DRIZZLE
SCENARIO. FOG IS DENSE OVER PARTS OF THE NC MTNS/FAR SW VA MTNS
INTO THE FOOTHILLS. 

ATTM...THINK THE DENSE FOG CAN BE COVERED BY AN SPS...BUT IF IT
STAYS AROUND A LITTLE LONGER...WILL ISSUE A DENSE FOG ADVISORY.
MODEL SOUNDINGS SUGGEST DENSE FOG POTENTIAL THROUGH ABOUT
07Z...THEN MORE OF A STRATUS LAYER.

WITH COLD ADVECTION LAGGING AND THE OCCLUDED FRONT NOT COMING
THROUGH MOST OF THE AREA UNTIL MORNING...I KEPT OVERNIGHT LOWS
CLOSER TO THE WARMER MAV. SATURDAY WILL BE A MILD DAY FOR ALL BUT
THE WESTERN MTNS AS WELL...WITH MORE OF A WEST-SOUTHWEST FLOW OF
COLD ADVECTION JUST GRADUALLY BRINGING COLDER AIR INTO TEH AREA. I
KEPT HIGHS SATURDAY ON THE WARM SIDE OF GUIDANCE...ESPECIALLY IN
THE PIEDMONT.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
COLD FRONT WILL CONTINUE PUSHING EAST OVER THE ATLANTIC AS SURFACE 
RIDGING NOSES IN FROM THE SOUTHWEST INTO THE WESTERN PORTION OF THE 
FORECAST AREA. COLDER DRIER AIR WILL FILTER FROM THE WEST ACROSS THE 
REGION WITH 850H TEMPERATURES BELOW 0 DEGREES C THROUGH MONDAY NIGHT. 
THE COLDEST AIR PUNCHES IN WITH -12 DEGREES C AT 850H IN SOUTHEASTERN 
WEST VIRGINIA SUNDAY NIGHT. MAX TEMPERTURES WILL RANGE FROM THE MID 
30S WEST OF THE BLUE RIDGE MOUNTAINS TO NEAR 50 IN THE PIEDMONT. 
WITH COLD AIR ADVECTION IN COMBINATION WITH THE CLOUDS 
THINNING...LOW TEMPERATURES WILL DROP INTO THE UPPER TEENS TO LOWER 
20S IN THE MOUNTAINS WITH MID 20S EAST SUNDAY AND MONDAY NIGHT.

A DISTURBANCE WILL APPROACH THE AREA SUNDAY NIGHT WITH A 
SOUTHWESTERLY FLOW OUT AHEAD INCREASING MOISTURE INTO THE WESTERN 
ZONES. AS THE WAVE APPROACHES...WINDS WILL VEER TOWARD THE WEST TO 
NORTHWEST GIVING WAY TO AN UPSLOPE COMPONENT. CONTINUE SLIGHT CHANCE 
POPS IN THE FAVORABLE WESTERN UPSLOPE REGIONS BUT THE MODELS SEEM TO 
BE SLOWING DOWN THE TIMING OF THE PRECIP WHICH MAY DELAY THE ONSET 
UNTIL LATER SUNDAY NIGHT. WITH TEMPERATURES BEING BELOW 
FREEZING...PRECIP WILL BEGIN AS ALL SNOW AND WILL CONTINUE THROUGH 
MONDAY NIGHT. 

850H WINDS INCREASE TO 40 TO 45 KNOTS IN WHICH THE RIDGETOPS COULD 
BECOME GUST TO 20 TO 25 MPH MONDAY MORNING AND LAST THROUGH THE DAY.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
MID-WEEK PERIOD LOOKS TRANQUIL WITH SURFACE HIGH PRESSURE CENTERED 
ACROSS THE MID-MISSISSIPPI VALLEY EARLY TUESDAY SLIDING EAST TO THE 
MID-ATLANTIC BY WEDNESDAY. CORE OF THE COLDEST AIR REMAINS WELL TO 
THE NORTH ACROSS NORTHERN NEW ENGLAND BUT WITH CLEAR SKIES AND H85 
TEMPS -2 TO -6C SHOULD SEE SEASONABLY CHILLY TEMPS TUE AND WED 
MORNINGS...GENERALLY UPPER TEENS WEST TO MID-20S EAST. HIGHS ALSO 
NEAR TO SLIGHTLY BLO LATE DEC NORMALS RANGING FROM LOW 30S NW TO 
MID-40S SE. BOTH GFS/ECMWF TRY TO DEVELOP LOW PRESSURE ALONG THE 
GULF COAST BY EARLY THU AS HIGH PRESSURE DEPARTS THE EAST COAST AND 
A SHORT-WAVE ROUNDS THE BASE OF THE LONG-WAVE TROUGH CENTERED 
SOMEWHERE IN THE CENTRAL CONUS. THE LATEST RUNS...12Z GFS AND 00Z 
EC...BOTH PRODUCE AN INVERTED TROUGH ALONG THE SOUTHEAST COAST BY 
LATER THU AND THEN WEAK LOW PRESSURE OFF THE CAROLINA COAST. WEAK 
LOW PRESSURE ALONG THE COAST IS ALSO SHOWN BY NEARLY ALL THE GFS 
ENSEMBLES WITH THE BULK OF THE PRECIPITATION SOUTHEAST OF THE 
FORECAST AREA. HOWEVER THE GENERAL PATTERN REMAINS SOMEWHAT 
FAVORABLE FOR MORE SIGNIFICANT COASTAL DEVELOPMENT LATE IN THE WEEK 
AND RUN TO RUN MODEL FLUCTUATIONS ARE TO BE EXPECTED IN FUTURE. FOR 
NOW HAVE SIMPLY MAINTAINED SLIGHT CHANCE OR CHANCE POPS FROM EARLY 
THURSDAY THROUGH THE END OF THIS FORECAST CYCLE.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
RAIN WILL BE LIFTING NE AWAY FROM THE REGION THIS EVENING...WITH
LIGHT DRIZZLE LINGERING. ALL SITES ARE EXPECTED TO BE IFR OR LOWER
THROUGH THE NIGHT WITH A LIGHTER WIND FLOW AND ABUNDANT LOW LEVEL
MOISTURE. THE IFR CONDITIONS WILL LIKELY HANG ON UNTIL
AROUND/AFTER 12Z SATURDAY. VFR CONDITIONS ARE THEN EXPECTED AT ALL
SITES BY 18Z SATURDAY.

THERE WILL BE TYPICAL MVFR TO LOCALIZED IFR RESTRICTIONS
CONTINUING IN THE UPSLOPE AREAS WEST OF THE BLUE RIDGE (KBLF/KLWB)
DUE TO STRATOCUMULUS AND SCATTERED SNOW SHOWERS THROUGH SUNDAY.

&&

.HYDROLOGY...
SOME AREA CREEKS AND RIVERS ARE RUNNING HIGH...INCLUDING THE
YADKIN RIVER...THE ROANOKE RIVER. LOOKS LIKE THE ROANOKE RIVER
WILL NOT REACH FLOOD STAGE...BUT THE YADKIN RIVER IN ELKIN MAY
APPROACH FLOOD STAGE OF 16 FEET. FLOOD WARNING CONTINUES FOR DAN
RIVER AT SOUTH BOSTON.

&&

.CLIMATE...
RECORD PRECIPITATION HAS BEEN SET AT BOTH ROANOKE AND BLACKSBURG
FOR THE MONTH OF DECEMBER. SEE THE LATEST RER FOR DETAILS. THE 1.42
INCHES OF PRECIP TODAY WAS THE 2ND MOST PRECIP FOR CHRISTMAS. THE
FIRST BEING 1.5 INCHES IN 1969.

&&

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

&&

$$
SYNOPSIS...JJ/WP
NEAR TERM...JJ/WP
SHORT TERM...REB
LONG TERM...PC
AVIATION...JJ/WP
HYDROLOGY...PC
CLIMATE...WP