FXUS61 KRNK 291504
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1004 AM EST SUN NOV 29 2009

.SYNOPSIS...
HIGH PRESSURE WILL BE ON CONTROL TODAY...THEN GIVE WAY TO A COLD 
FRONT APPROACHING FROM THE WEST EARLY MONDAY...WHICH WILL PASS 
THROUGH THE APPALACHIANS AND INTO THE PIEDMONT BY EARLY AFTERNOON 
MONDAY. WEDNESDAY AND THURSDAY...A LARGE LOW PRESSURE SYSTEM WILL 
MOVE FROM THE LOWER MISSISSIPPI VALLEY ACROSS THE MID ATLANTIC 
STATES.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A WEAK SHORT WAVE MOVING INTO SOUTH CAROLINA WAS BRINGING SOME MID
AND HIGH CLOUDS TO THE SOUTHERN FORECAST AREA. BUT NOT ENOUGH
CLOUD COVER TO KEEP TEMPERATURES FROM CLIMBING QUICKLY THIS
MORNING. WITH 850 MB TEMPERATURES AROUND +9 MOST LOCATIONS WILL
HAVE HIGH TEMPERATURES ABOVE NORMAL AGAIN TODAY. ONLY MINOR
CHANGES MADE TO THE FORECAST FOR THIS AFTERNOON. 

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
THE FRONT SO FAR HAS VERY LITTLE MSTR TO WORK WITH BUT THE
SYSTEM SHOULD BEGIN TO TAP SOME GULF MSTR BY TONIGHT AS IT MOVES
INTO OHIO VALLEY AND EAST OF THE MISSISSIPPI RIVER. MODELS ARE IN
GOOD AGREEMENT WITH TIMING OF FRONT TO REACH WRN SLOPES BETWEEN
09Z AND 12Z MONDAY...THEN QUICKLY PUSH EAST OF THE CWA BETWEEN 15Z
AND 18Z...JUMPING INTO A WEAK LEE TROUGH. THIS IS A LITTLE FASTER
THAN PREVIOUS RUNS. 

LOOKS LIKE MUCH OF THE PRECIP WILL BE RIGHT WITH THE FRONT AND A
LITTLE BEHIND IT...AND GIVEN FAST MOVEMENT AND TAPPING GULF MSTR
LATE IN THE GAME...NOT LOOKING AT QPF VALUES OVER A QTR OF AN INCH
IN THE WEST...WITH THE USUAL BREAK UP OF SHWRS TO SOME DEGREE AS
IT PASSES OVER BLUE RDG...AND THEN SOME REDEVELOPMENT AGAIN TO THE
EAST...AND MAYBE JUST ON OUR FAR SOUTHEASTERN FRINGE. AS
SUCH...WENT WITH CATEGORICAL POPS IN WEST STARTING 12Z
MONDAY...AND THIS MAY NOT BE SOON ENOUGH...TO LIKELY UP TO ABOUT
THE BLUE RIDGE...THEN DROPPING TO CHC ACROSS MOST OF THE WEST WITH
LOW LIKELY IN THE PIEDMONT AFTER 18Z...BUT EVEN THIS QUICKLY
DROPPING TO CHC BY 21Z. PROBABLY WILL NEED TO SPEED THIS UP EVEN
MORE. USED SREF PRECIP PROBABILITIES TO TIME MOST OF THESE
POPS...AND TO SHOW A SMALL GAP IN CENTRAL PART OF CWA WHERE NOT
EVEN WORTH GOING WITH LIKELY POPS AS SHWRS WITH FRONT BREAK UP A
LITTLE.

FOR MONDAY TEMPS...ALSO WENT CLOSER TO MAV GUIDANCE WITH COOLER 
HIGHS IN THE WEST AND BOTH MAV AND MET SIMILAR IN THE EAST. TEMPS 
MAY END UP WARMER THAN GUIDANCE IN THE EAST IF PRECIP MOVES OUT MORE 
QUICKLY AND A PERIOD OF AFTERNOON SUN WITH DOWNSLOPE 
WARMING...DESPITE THE COLD ADVECTION...TAKES PLACE.

UPSLOPE SHWRS MAY CONTINUE IN FAR WRN SLOPES OF WEST VIRGINIA 
THROUGH MONDAY EVENING...BUT FLOW TURNS FROM NW TO WESTERLY
PRETTY QUICKLY SO NOT IDEAL. DECIDED TO KEEP A SMALL STRIP OF
LIKELY ACROSS WRN GREENBRIER TO FLAT TOP...AS COLDER AIR MOVES IN
LATE IN DAY AND OVERNIGHT TO TURN RAIN SHOWERS INTO SNOW SHWRS.
VERY MINOR ACCUMULATIONS...IF ANY...GIVEN VERY LITTLE MSTR AND
POOR TRAJECTORIES...AS WELL AS SHORT LIVED NW FLOW CONDITIONS. BY
06Z...ANY LINGERING SNOW SHWRS SHOULD BE FADING AWAY UP THERE AS
FLOW TURNS WESTERLY.

BEHIND THE FRONT I INCREASED WINDS ALONG RIDGES A BIT GIVEN A 
SLIGHT UPWARD TREND IN MODEL GUIDANCE...BUT STILL WELL SHORT OF ADV 
CRITERIA. 

SURFACE HIGH PRESSURE WILL CROSS EAST OVER THE AREA TUESDAY INTO 
TUESDAY NIGHT. AS SKIES CLEAR OUT TUESDAY AFTERNOON TEMPERATURES 
WILL BE HOVERING NEAR SEASONAL NORMS GIVE OR TAKE A COUPLE DEGREES.

A LOW PRESSURE SYSTEM DEVELOPS OVER THE GULF OF MEXICO AND SLIDES 
NORTHEAST BRINGING OUR NEXT CHANCE FOR PRECIP WEDNESDAY INTO 
THURSDAY. MODELS ARE HAVING A HARD TIME AGREEING ON THE TIMING OF 
THIS SYSTEM. ECMWF HAS BEEN CONSISTENTLY SLOWER THAN THE GFS IN ITS 
LATEST RUNS. HAVE LEANED TOWARD THE ECMWF AND HAVE SLOWED THE FRONT 
COMING INTO THE FORECAST AREA. AS A RESULT...HAVE LINGERED THE 
PRECIP A LITTLE LONGER ACROSS THE FORECAST AREA. DECENT OVERRUNNING 
PRECIP WILL SPREAD ACROSS THE COUNTY WARNING AREA WEDNESDAY 
AFTERNOON BEGINNING IN THE SOUTHWEST AND PUSHING NORTH NORTHEAST. 
RAIN COULD BE HEAVY AT TIMES WITH MOIST WARM AIR ADVECTING OVER THE 
REGION AND AN INCREASING LOW LEVEL JET. RAINFALL AMOUNTS OF A HALF 
OF AN INCH TO AN INCH POSSIBLE WEDNESDAY INTO THURSDAY MORNING. 
HIGHER AMOUNTS OF AN INCH OR TWO POSSIBLE ALONG EASTERN SLOPES OF 
THE BLUE RIDGE. 

MODELS PROG A LOW LEVEL JET INCREASING TO 40 TO 50 KNOTS EAST OF THE 
BLUE RIDGE MOUNTAINS CONCENTRATED IN THE PIEDMONT AREAS OF VIRGINIA 
AND NORTH CAROLINA. WILL HAVE TO MONITOR THE SITUATION TO SEE HOW 
THE WINDS PLAY OUT TO SEE IF THEY WILL REACH ANY ADVISORY CRITERIA. 

WEDNESDAY WILL BE DAMP AND COLD. MAX TEMPERATURE READINGS WILL BE IN 
THE 40S IN THE MOUNTAINS TO LOWER 50S IN THE PIEDMONT AREAS 
WEDNESDAY. EXPECTING THE COLD AIR TO ADVECT IN LATE WEDNESDAY NIGHT 
BUT IF THE FRONT MOVES EVEN SLOWER...THEN THE COLDER AIR WILL NOT 
GET INTO THE AREA UNTIL THURSDAY NIGHT OR POSSIBLY LATER.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
THURSDAY WILL CONTINUE TO BE DAMP AND COLD IN THE WESTERN ZONES  
WITH HIGH TEMPERATURES IN THE LOWER 40S IN SOUTHEAST WEST VIRGINIA 
TO UPPER 50S IN THE PIEDMONT. THIS IS DUE TO A NORTHWESTERLY FLOW IN 
THE WAKE OF THE FRONT AND THE DOWNSLOPING COMPONENT WILL WARM UP 
READINGS A COUPLE DEGREES IN THE EAST FOR THURSDAY.

THE FRONT WILL BE EXITING THE AREA TO THE NORTHEAST THURSDAY NIGHT 
INTO FRIDAY WITH A LOW DEEPENING OFF THE COAST OF MAINE. UPSLOPE 
FLOW AND WRAP AROUND MOISTURE WILL MAINTAIN POSSIBLE SNOW SHOWERS 
ALONG THE USUAL WESTERN UPSLOPE REGION OF SOUTHEAST WEST VIRGINIA  
AND THE MOUNTAIN EMPIRE THROUGH FRIDAY. THE POPS WILL THEN TAPER OFF 
FRIDAY NIGHT AS HIGH PRESSURE BUILDS INTO THE AREA FROM THE 
SOUTHWEST BY THE WEEKEND.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS EXPECTED UNDER HIGH PRESSURE THROUGH EARLY MONDAY MORNING. 
A COLD FRONT WILL ARRIVE IN THE WEST BY AROUND DAWN MONDAY...WHICH SHOULD
BRING SOME MVFR OR LOWER CIGS TO THE BLF/LWB AREA...MAYBE EVEN TO
ROANOKE BY LATE AFTERNOON MONDAY. PLACED AN MVFR CIG AT BLF BEFORE
12Z IN THE TAF. ANY IFR CONDITIONS SHOULD BE VERY BRIEF AND PRECIP
WILL BE RATHER LIGHT. A BRIEF SNOW SHWR IS POSSIBLE BEHIND THE
FRONT MONDAY EVENING AT BLF AND LWB...BUT NOT EXPECTED TO HAVE ANY
IMPACT ON FLIGHT CATEGORIES. 

ANOTHER STORM SYSTEM WILL BRING A GOOD CHANCE FOR SIGNIFICANT RAIN
BY MIDWEEK...AND LOOKS LIKE A BETTER CHANCE FOR MORE WIDESPREAD
IFR CONDITIONS WITH THIS SYSTEM.

&&

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

&&

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