National Weather Service Weather Forecast Office

Area Forecast Discussion

545
FXUS62 KGSP 031951
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
251 PM EST SUN MAR 3 2013

.SYNOPSIS...
WEAK HIGH PRESSURE BUILDS IN MONDAY AS A STRONG LOW PRESSURE SYSTEM
BEGINS TO MOVE SOUTHEAST THROUGH THE LOWER OHIO VALLEY BRINGING WITH
IT ABUNDANT MOISTURE. THE LOW PRESSURE SYSTEM WILL CROSS THE WESTERN
CAROLINAS ON WEDNESDAY...WITH HIGH PRESSURE RETURNING THROUGH THE
LATE WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 200 PM...A N-S ORIENTED CHANNELED VORT LOBE HAS ENTERED THE
WRN PART OF THE CWFA...AND SHUD EXIT TO THE EAST BY EARLY EVENING.
THE MID AND UPR QG FORCING WITH THIS FEATURE IS FAIRLY WEAK...AND
NOT TRANSLATING TO MUCH LIFT IN THE LLVLS. IN FACT...CUMULUS IS
STRUGGLIGN TO DEVELOP ACRS THE PIEDMONT ZONES THANKS TO LOW SFC
DWPTS. THERE IS STILL A DECENT STRATOCUMULUS DECK ACRS ERN
KY/TN...WITH OCCASIONAL FLURRIES AND ISOLD SNOW SHWRS ALONG THE
TN/NC BORDER. THIS ACTIVITY DOESN/T APPEAR TO BE CAUSING ANY
ADDITIONAL PROBLEMS WITH THE ROADS...AND SHUD OVERALL WANE LATER
THIS AFTN INTO THIS EVENING. OTHERWISE...A CHILLY DAY ACRS THE
REGION WITH TEMPS 10-20 DEG BELOW NORMAL FOR EARLY MARCH.

LATER TONIGHT...HIGH PRES SYSTEM BUILDS INTO THE AREA...WITH MOSTLY
CLEAR SKIES AND DIMINISHING WINDS. TEMPS EXPECTED TO BE SIMILAR TO
LAST NIGHT (ABOUT 10-15 DEG BELOW NORMAL).

MONDAY...MODELS GENERALLY AGREE ON THICKENING CIRRUS SPILLING OVER
THE UPPER RIDGE INTO THE AREA THRUT THE DAY. HOWVER...THE LLVLS WILL
BE VERY DRY...AS CENTER OF MODERATING POLAR AIR MASS CROSSES THE
REGION. THICKNESSES REBOUND UNDER THE BUILDING RIDGE...BUT STILL
REMAIN ONE TO TWO CATEGORIES BELOW NORMAL. THIS COMBINED WITH THE
DRY AIR WILL RESULT IN VERY LOW AFTN RH (SEE FIRE WX SECTION BELOW).

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 230 PM SUNDAY...THE SHALLOW UPPER RIDGE WILL BE MOVING EAST
AND OUT OF THE AREA MONDAY EVENING. AN UPPER LOW WILL BE OVER THE
DAKOTAS AT 00Z TUESDAY AND MOVE TO NC BY 12Z WEDNESDAY. ALTHOUGH THE
GFS HAS A TONGUE OF LIGHT PRECIP CROSSING THE NC MTNS AT 00Z
TUESDAY...ALL OTHER MODELS HOLD OFF ON INITIAL PRECIP UNTIL AROUND
06Z TUESDAY. NOT ALL GUIDANCE AND MODELS AGREE...BUT STILL FEEL
ENOUGH COLD AIR WILL BE IN PLACE ALONG THE SPINE OF THE NC MTNS TO
HAVE LIGHT FREEZING RAIN AT THE ONSET OF THIS SYSTEM. AT THIS
POINT...A TRACE TO 0.03 ICE ACCUM POSSIBLE FROM BALSAM TO
WEAVERVILLE TO NEWLAND UP UNTIL JUST AFTER SUNRISE TUESDAY.  AT THAT
TIME ALL PRECIP SHOULD QUICKLY CHANGE OVER TO RAIN. SURFACE LOW
PRESSURE FORMS OVER ARKANSAS MONDAY NIGHT AND MOVES TO OHIO BY 00Z
WEDNESDAY AS THE UPPER LOW REACHES ILLINOIS. THE COLD FRONT
EXTENDING SOUTH OF THE SURFACE LOW WILL BE PRECEDED BY INSTABILITY
WITH CAPE VALUES IN THE 100 TO 200 RANGE ON THE GFS AND LESS THAN
100 J/KG ON THE NEW ECMWF. SLIGHT CHANCE THUNDER WILL BE CROSSING
THE FORECAST AREA AROUND 00Z WEDNESDAY. AFTER THAT...TEMPS DROP
TUESDAY NIGHT AND THE RAIN CHANGES OVER TO SNOW IN THE NC MTNS. SNOW
SHOWERS CONTINUE ALONG THE TN BORDER THROUGH WEDNESDAY AS RAIN
SHOWERS TAPER OFF IN THE PIEDMONT. NOW GOING FOR UP TO 7 INCHES OF
SNOWFALL IN THE BULADEAN AND BEECH MTN AREA AS A TOTAL FOR WED AND
WED NIGHT. WILL BE QUITE BREEZY TO WINDY BY MID TO LATE DAY WED AS A
MORE POWERFUL SURFACE LOW DEEPENS TOWARD THE CAROLINA COAST. HIGH
TEMPS AROUND 10 DEGREES BELOW NORMAL TUESDAY AND 15 OR MORE BELOW ON
WEDNESDAY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AT 230 PM EST SUNDAY...A CLOSED UPPER LOW WILL BE NEAR THE MID
ATLANTIC COAST ON WEDNESDAY NIGHT...WHILE A RIDGE WILL BE UPSTREAM
OVER THE PLAINS. THIS RIDGE PROGRESSES VERY SLOWLY ON THURSDAY...
ONLY CROSSING THE MS RIVER VALLEY ON FRIDAY...AND THE SOUTHERN
APPALACHIANS ON SATURDAY. ON SUNDAY THE RIDGE AXIS CROSSES THE EAST
COAST...WHILE AN UPPER LOW MOVES INTO THE PLAINS FROM THE SOUTHERN
ROCKIES.

A SURFACE WAVE WILL MOVE OFF THE CAROLINA COAST SUNDAY NIGHT...WHILE
A TIGHT PRESSURE GRADIENT KEEP NW FLOW OVER THE WESTERN CAROLINA AND
NE GA...WITH NW FLOW SNOW SHOWERS NEAR THE TN BORDER. ON FRIDAY HIGH
PRESSURE MOVES EAST ACROSS THE TN VALLEY AND THE PRESSURE GRADIENT
RELAXES. HIGH PRESSURE CROSSES THE APPALACHIANS ON SATURDAY...
DRIFTING INTO SC ON SUNDAY...WHILE THE GULF OPENS UP TO MOIST INFLOW
BETWEEN THE FL PANHANDLE AND TX. TEMPERATURES WILL WARM WITH RISING
HEIGHTS ALOFT...REACHING NEAR NORMAL VALUES NEXT WEEKEND.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS ARE EXPECTED THROUGH THE 18Z
TAF PERIOD. WINDS HAVE BECOME RATHER VARIABLE THIS AFTN...AS A LEE
TROF TRIES TO ESTABLISH ACRS THE PIEDMONT. GENERALLY...EXPECT WINDS
TO FAVOR A NORTHWEST DIRECTION AT KCLT AND KHKY...AND SW AT KGMU AND
KAND. KGSP IS MOST UNCERTAIN...AS A GAP WIND HAS KEPT A CONSISTENT
NNW DIRECTION SO FAR TODAY...BUT LEE TROF MAY BRING WINDS BACK TO W
OR WSW. FEW TO SCT HIGH BASED STRATOCUMULUS IS DEVELOPING ACRS THE
LWR PIEDMONT. MAY SEE PERIODS OF BKN050 AT KCLT THRU THE AFTN. SKIES
CLEAR THIS EVENING...THEN SOME INCREASING HIGH CLOUDS BEGIN TO
RETURN FROM THE WEST AHEAD OF THE NEXT SYSTEM.

AT KAVL...PESKY CLOUDS JUST ABOVE 3000 FT CONTINUE TO AFFECT THE
TERMINAL FROM THE N. I WILL KEEP A TEMPO FOR OCCASIONAL CIGS AROUND
3500 FT. OTHERWISE...EXPECT CHANNELED UP-VALLEY FLOW TO KEEP
BRISK/GUSTY NNW WINDS INTO THIS EVENING....BEFORE FINALLY SLACKING
OFF OVERNIGHT. ALSO SHUD SEE DECREASE IN CLOUDS LATER THIS AFTN.

OUTLOOK...SFC HIGH PRESSURE WILL SUPPLY LIGHT WINDS AND VFR
CONDITIONS ON MONDAY. MONDAY NIGHT THROUGH WEDNESDAY...A LARGE LOW
PRESSURE SYSTEM WILL TRACK FROM WEST TO EAST ACROSS THE WESTERN
CAROLINAS. DEEP MOISTURE AND PRECIPITATION WILL LIKELY RESULT IN
RESTRICTIVE CEILINGS AND VISIBILITY AS THE LOW PASSES...ESPECIALLY
ACROSS THE NC TERMINALS. VFR CONDITIONS SHOULD RETURN ON THURSDAY
AND REMAIN INTO THE WEEKEND.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-20Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...PAT
NEAR TERM...ARK
SHORT TERM...DEO
LONG TERM...JAT
AVIATION...ARK