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FXUS62 KRAH 012048
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
345 PM EST SUN MAR 01 2009

.SYNOPSIS...
A STRENGTHENING STORM SYSTEM OVER THE DEEP SOUTH WILL SWING EAST 
THEN NORTHEAST UP THE CAROLINA COAST THROUGH EARLY MONDAY MORNING. 
AS COLD AIR SPILLS INTO OUR REGION... WINTER STORM CONDITIONS ARE 
POSSIBLE OVER PORTIONS OF OUR REGION LATE SUNDAY INTO MONDAY.

&&

.NEAR TERM /TODAY THROUGH TONIGHT/...
AS OF 345 PM SUNDAY...

A WINTER STORM WARNING REMAINS IN EFFECT THIS AFTERNOON THROUGH MID 
MORNING MONDAY FOR AREAS ALONG AND WEST OF HIGHWAY 1. A WINTER 
WEATHER ADVISORY REMAINS IN EFFECT FOR THE REMAINDER OF THE 
CWA EXCEPT FOR THE FAYETTEVILLE / CLINTON / GOLDSBORO AREAS FOR 
TONIGHT.

THROUGH EARLY EVENING: WE STILL EXPECT A BRIEF LULL THIS EVENING IN 
THE WIDESPREAD PRECIPITATION ACROSS CENTRAL NC... AS A PRONOUNCED 
MID LEVEL DRY SLOT EAST OF THE UPPER LOW PUNCHES ACROSS OUR REGION. 
INDEED... THE BACK EDGE OF THE INITIAL PRECIPITATION SHIELD--DRIVEN 
BY STRONG UPWARD MOTION IN THE DIFLUENT DEFORMATION ZONE NORTH AND 
NORTHEAST OF THE UPPER LOW... IN THE DIVERGENT EXIT REGION OF A NOW 
120+ KT JET NOW NOSING INTO WESTERN NC... AND A DEEP ZONE OF INTENSE 
FGEN OVER THE CAROLINAS--HAS RECENTLY CROSSED THE SC/NC STATE LINE. 
BEFORE THIS BANDED PRECIPITATION SHIELD EXITS... A QUICK CHANGEOVER 
TO SLEET AND SNOW (WITH LITTLE SNOW/SLEET ACCUMULATION) IS LIKELY 
OVER THE NW PIEDMONT THROUGH EARLY EVENING... OWING TO AN ERODING 
WARM NOSE ALOFT SAMPLED BY THE LATEST AMDAR SOUNDINGS AND 18Z RAOB 
AT GSO. IN FACT... LOCATIONS JUST TO THE WEST FROM HICKORY TO MOUNT 
AIRY TO REIDSVILLE HAVE RECENTLY CHANGED OVER TO ALL SNOW THIS 
AFTERNOON. THE WARM NOSE IS FORECAST TO REMAIN PRONOUNCED OVER THE 
TRIANGLE EASTWARD THROUGH 00Z... SO ONLY RAIN WITH A BRIEF POCKET OF 
SLEET IS EXPECTED WITH THIS FIRST PRECIPITATION SHIELD. 

OVERNIGHT: THE TRAILING DEFORMATION/COMMA HEAD/TROWAL PRECIPITATION 
BAND OVER THE DEEP SOUTH IS FORECAST TO PIVOT NORTHEASTWARD... JUST 
WEST OF THE TRACK OF THE VERY DYNAMIC UPPER LOW CENTERED OVER 
CENTRAL GA BORDER AT 20Z... AS THE LOW LIFTS NORTHEASTWARD THROUGH 
THE CENTRAL CAROLINAS TONIGHT. INCREDIBLY... ALL MODELS ARE FINALLY 
IN VERY GOOD AGREEMENT SHOWING AROUND 0.15' LIQUID EQUIVALENT AT RWI 
TO AROUND 0.30' AT RDU TO AROUND TO 0.60' OVER THE WESTERN PIEDMONT 
OVERNIGHT... WITH THE SWEET SPOT ACCORDINGLY RUNNING FROM WADESBORO 
TO ASHEBORO TO GREENSBORO. USING A 10-14:1 SNOW RATIO-- HIGHEST AND 
EARLIEST WEST-- AND TAKING INTO ACCOUNT SOME INITIAL MELTING DUE TO 
THE WET GROUND AND ONLY MARGINALLY COLD SURFACE TEMPERATURES... THIS 
YIELDS SNOW ACCUMULATIONS FROM 3-6 INCHES OVER THE WESTERN PIEDMONT 
TO A RANGE OF 2-4 INCHES FROM EAST TO WEST ACROSS THE EASTERNMOST 
TIER OF WARNED COUNTIES FROM ROCKINGHAM TO RALEIGH TO WARRENTON... 
TO AROUND AN INCH IN THE I-95 CORRIDOR. SOME LOCATIONS WITHIN THE 
HEART OF THE DEFORMATION BAND COULD RECEIVE LOCALLY HIGHER AMOUNTS. 
IT IS IMPORTANT TO STRESS THAT ANY CHANGE IN TRACK OF THE MID LEVEL 
LOW COULD SHIFT THESE PRECIPITATION AMOUNTS SLIGHTLY EAST OR WEST. 
LOW WIND CHILLS IN THE TEENS ARE EXPECTED OVERNIGHT... AS STRONG AND 
GUSTY NORTHEASTERLY WINDS VEER TO N THEN NW AND INCREASE TO 15-20 
MPH SUSTAINED WITH GUSTS 30-35 MPH. LOW TEMPERATURES 24 TO 31 NW TO 
SE. 

&&

.SHORT TERM /MONDAY/...
AS OF 345 PM SUNDAY...

MONDAY WILL BE QUITE COLD AND BLUSTERY... AS THE MSLP GRADIENT 
REMAINS TIGHT BETWEEN THE NEW ENGLAND COAST BOUND ~1000 MB WINTER 
CYCLONE AND INCOMING ~1035 MB ARCTIC HIGH PRESSURE FROM THE GREAT 
LAKES. EXPECT NW WINDS OF 13-17 MPH WITH GUSTS 25-30 MPH THROUGH 
MIDDAY... TAILING OFF AS THE GRADIENT RELAXES IN THE AFTERNOON. HIGH 
TEMPERATURES WITH AN EXPECTED FRESH SNOW PACK EXPECTED TO RANGE FROM 
AROUND FREEZING OVER THE WESTERN PIEDMONT TO MIDDLE 30S IN THE 
COASTAL PLAIN. 

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
AS OF 355 AM SUNDAY...

MAIN CHANGE TO THE LONG TERM WAS TO ADJUST TEMPS DOWNWARD MONDAY 
NIGHT AND TUESDAY IN ANTICIPATION OF SNOW COVERAGE. ARCTIC HIGH OVER 
THE GREAT LAKES WILL BUILD/DROP SEWD TOWARD CENTRAL NC MON NIGHT AND 
TUESDAY. WHILE NOT EXPECTING NEAR SURFACE LAYER TO DECOUPLE...STILL 
EXPECT VERY COLD MIN TEMPS BY TUESDAY MORNING DUE TO THE ABNORMALLY 
COLD AIR ASSOCIATED WITH THE HIGH. MODEL THICKNESSES IN THE 1240S 
HISTORICALLY SUPPORT MIN TEMPS CLUSTERING AROUND 11-12 DEGREES 
ABOVE. MOS GUIDANCE TRENDING COOLER SO HAVE ADJUSTED MIN TEMPS 
SIMILAR TO HISTORICAL VALUES (NEAR 12 DEGREES NW TO 17/18 DEGREES 
FAR SE. SURFACE HIGH SETTLES OVER REGION BY LATE IN THE DAY. FULL 
SUN THICKNESSES SUGGEST MAX TEMPS IN THE MID/UPPER 30S. ACCOUNTING 
FOR EARLY MARCH SUN ANGLE AND WINDS BECOMING LIGHT...EXPECT MAX 
TEMPS TO RANGE UPPER 30S IN THE NW TO THE LOWER/MID 40S SOUTH. 
DEPENDING UPON DEPTH OF SNOW PACK...MAX TEMPS TUESDAY MAY END UP 
BEING A FEW DEGREES COOLER.

WEDNESDAY THROUGH SATURDAY WILL SEE A WARMING TREND AS L/W TROUGH 
LIFTS NE AND UPPER LEVEL FLOW BACKS WESTERLY. TEMPS SHOULD RETURN TO 
NEAR NORMAL LEVELS THU WITH ABOVE NORMAL VALUES EXPECTED FRI AS LOW 
LEVEL FLOW BECOMES SW IN RESPONSE TO SURFACE RIDGE DRIFTING OFFSHORE 
AND A COLD FRONT ADVANCING EAST ACROSS THE MID MS VALLEY AND LOWER 
OH VALLEY. EXPECT TO SEE AN INCREASE IN CLOUDINESS AS WARM AIR 
ADVECTION PATTERN WILL ALSO INCREASE MOISTURE ACROSS THE REGION. 
HOWEVER FRI INTO SATURDAY PERIOD STILL APPEARS TO BE DRY AS BEST 
FORCING FOR PRECIP REMAINS TO OUR NW. ABOVE NORMAL TEMPS EXPECTED ON 
SATURDAY...IN THE UPPER 60S TO NEAR 70. DEPENDING UPON CLOUD 
COVERAGE...MAX TEMPS SATURDAY COULD EASILY BE IN THE LOW/MID 70S.-WSS

&&

.AVIATION /12Z SUNDAY THROUGH FRIDAY/...
AS OF 230 PM SUNDAY...

IFR/LIFR CONDITIONS EXPECTED THROUGH TONIGHT... GRADUALLY IMPROVING 
TO MVFR EARLY MONDAY. 

WIDESPREAD PRECIPITATION (RAIN EXCEPT FOR A CHANGEOVER TO SLEET AND 
SNOW AT INT AND GSO)--IN ADVANCE OF A VIGOROUS UPPER LEVEL LOW--WILL 
GRADUALLY TAPER OFF FROM SW TO NE ACROSS CENTRAL NC THROUGH THE 
REMAINDER OF THE AFTERNOON AND EVENING... AS A MID LEVEL DRY SLOT 
SPREADS INTO OUR REGION FROM THE SOUTH. HOWEVER... PRECIPITATION IS 
EXPECTED TO SPREAD BACK ACROSS CENTRAL AND WESTERN NC TONIGHT... AS 
A COMMA HEAD OF PRECIPITATION (SNOW) OVER THE DEEP SOUTH THIS 
AFTERNOON PIVOTS NE'WRD. THE SNOW WILL BE MOST WIDESPREAD AND 
INTENSE (LOWEST VISIBILITIES) FROM RDU WESTWARD... WITH LIGHTER SNOW 
AT FAY AND RWI. CIGS WILL REMAIN IFR/LIFR THROUGH TONIGHT... THEN 
BECOME MVFR AS THE SNOW EXITS OUR REGION EARLY MONDAY. STRONG AND 
GUSTY (SUSTAINED 12-18 KTS GUSTS 25-30 KTS) NE WINDS WILL GRADUALLY 
BACK TO NW THROUGH EARLY MONDAY... AS A STRONG SURFACE LOW LIFTS 
NORTHEASTWARD ALONG THE NC COAST. THE WIND AND RESULTANT BLOWING 
SNOW MAY CAUSE SOME REDUCED VISIBILITIES AT EVEN AFTER THE 
PRECIPITATION ENDS... BUT HAVE NOT INCLUDED THIS RARE OCCURENCE AT 
THIS TIME. 

HAVE ALSO INCLUDED LLWS... THIS EVENING... WHEN WINDS AT 2 THSD FT 
ARE EXPECTED TO INCREASE TO AROUND 50 KTS WITHIN A PRONOUNCED LOW 
LEVEL INVERSION. THIS THREAT WILL DIMINISH AS THE INVERSION LIFTS 
AND ERODES LATE EVENING AND OVERNIGHT. 

VFR CONDITIONS MAKE A RETURN FROM WEST TO EAST LATE MONDAY 
AFTERNOON... AND WILL PERSIST INTO THURSDAY AS HIGH PRESSURE SETTLES 
INTO AND LINGERS OVER OUR REGION.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM NOON TODAY TO 9 AM EST MONDAY FOR 
NCZ007>010-021>026-038>041-073>076-083-084.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 9 AM EST 
MONDAY FOR NCZ011-027-028-042-043-077-085-086.

&&

1138

SYNOPSIS...MWS/HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...WSS
AVIATION...MWS