Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 032038
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
438 PM EDT TUE MAY 3 2016

.SYNOPSIS...
A COLD FRONT WILL MOVE SLOWLY EAST OF THE AREA THROUGH TONIGHT. A
COOLER AND DRIER AIR MASS WILL MOVE IN BEHIND THE FRONT ON
WEDNESDAY. ANOTHER COLD FRONT WILL CROSS THE REGION WEDNESDAY NIGHT
AND USHER IN A MUCH COOLER AIR MASS FROM CANADA FOR THE END OF THE
WORK WEEK. HIGH PRESSURE SHOULD RETURN WITH A WARMING TREND FOR THE
BALANCE OF THE WEEKEND...WITH A FRONT SLOWLY APPROACHING FROM THE
NORTH.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 430 PM...STRONG STORMS STILL ONGOING ACROSS THE WATCH AREA...
WITH ISOLATED STORMS FORMING BACK OVER THE NC FOOTHILLS. ISOLATED
STORMS ARE LINGERING ACROSS THE LAKELANDS AS WELL. LATEST MESOSCALE
GUIDANCE SHOWS THE BEST COVERAGE WILL REMAIN OVER THE WATCH AREA...
SCATTERED COVERAGE BACK TOWARD THE FOOTHILLS...AND ISOLATED AT BEST
ELSEWHERE BEFORE DIMINISHING WITH LOSS OF HEATING AND EASTWARD
MOVEMENT OF THE FRONT AND DEEP MOISTURE. HAVE UPDATED POP TO SHOW
THESE TRENDS. WILL LEAVE THE WATCH IN PLACE FOR NOW GIVEN THE
ONGOING STRONG STORMS.

LATER TONIGHT...A COLD FRONT SHOULD PUSH EAST OF THE AREA...AND 850
MB FLOW WILL PICK UP OUT OF THE NW. DRIER AIR WILL WORK IN AND
SHOULD CUT OFF POPS TO JUST ALONG THE TN BORDER THANKS TO UPSLOPE BY
DAYBREAK WEDNESDAY. THIS WILL BE IN SPITE OF A MORE POTENT SHORTWAVE
TROF APPROACHING FROM THE WEST AS IT ROUNDS THE BASE OF THE LONG
WAVE TROF OVER THE OH/TN VALLEYS. BOTH THE GFS AND NAM SHOW
LINGERING MID LEVEL MOISTURE...SO I EXPECT THIS WAVE WILL AT LEAST
FORCE A FAIR AMOUNT OF MID LEVEL CLOUDINESS OVERNIGHT. TEMPS WILL
RUN A CATEGORY OR TWO ABOVE NORMAL.

WEDNESDAY...ANOTHER POTENT SHORTWAVE WILL DIVE THRU THE LONGWAVE
TROF AXIS...SHARPENING THE TROF AND CLOSING OFF AN UPPER LOW BY END
OF THE DAY OVER THE OHIO VALLEY. A SECONDARY COLD FRONT ASSOCIATED
WITH THIS ENERGY WILL BE KNOCKING ON THE DOOR OF THE NC MTNS BY 00Z
THU. THE FRONT WILL HAVE SOME MOISTURE WITH IT...AND POPS WILL START
TO RAMP UP ALONG THE TN/NC BORDER DURING THE DAY. EAST OF THE
MTNS...MID CLOUDS ARE EXPECTED TO THIN OUT RESULTING IN A PARTLY TO
MOSTLY SUNNY DAY. HOWEVER...THICKNESSES FALL SHARPLY FROM PREVIOUS
DAY...SO TEMPS WILL BE NOTICEABLY COOLER WITH LESS HUMIDITY. HIGHS
WILL BE AT OR SLIGHTLY BELOW NORMAL.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 230 PM EDT TUESDAY...A 500 MB LOW CENTER WILL MOVE SOUTHEAST
OVER THE SOUTHERN APPALACHIANS WED NIGHT THROUGH THU. H5 TEMPS WILL
DIP TO MINUS 25 DEG C OR COLDER UNDER THE LOW CENTER...WITH STEEP
MID LEVEL LAPSE RATES RESULTING THROUGH THE SHORT RANGE PERIOD. MOST
OF THE MOISTURE ASSOCIATED WITH THE UPPER LOW AND REINFORCING
SURFACE COLD FRONT SHOULD BE AT LOW LEVELS...WITH NW UPSLOPE
MOISTURE BEING THE MAIN DRIVER FOR WESTERN MOUNTAIN PRECIPITATION
EARLY THU THROUGH FRI. ALTHOUGH PROFILES GET MARGINALLY COLD ENOUGH
FOR SNOW OR GRAUPEL ALONG THE HIGHEST RIDGES...ESPECIALLY THU
MORNING...A SURFACE BASED WARM LAYER SHOULD KEEP ANY ACCUMULATIONS
AT BAY. WILL ALSO PERMIT LOWER CHANCE PROBABILITIES FOR SHOWERS TO
SPREAD EAST ALONG MAINLY THE INTERSTATE 40 CORRIDOR THROUGH THU
AFTN. THE 500 MB LOW CENTER WILL THEN MEANDER AND VERY SLOWLY FILL
ALONG THE EASTERN SEABOARD THU NIGHT THROUGH FRI...WITH WESTERN
CAROLINA PRECIPITATION CHANCES SLOWLY DIMINISHING.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 240 PM EDT TUESDAY...500 MB HEIGHTS WILL RISE FROM THE WEST ON
SATURDAY AS THE CLOSED UPPER LOW DEPARTS TO THE EAST. DRIER SURFACE
HIGH PRESSURE MOVE INTO PLACE...BUT WITH A SLOWLY APPROACHING BACK
DOOR COLD FRONT OVER THE WEEKEND. BETTER MOISTURE POOLING ALONG THE
COLD FRONT COULD FLIRT WITH THE NORTHERN TIER LATE IN THE
WEEKEND...BUT WITH FAIRLY LOW PRECIPITATION CHANCES. THE BOUNDARY
SHOULD STALL SOMEWHERE IN THE REGION SUNDAY INTO MONDAY...BEFORE
RETURNING NORTH AS A WARM FRONT EARLY NEXT WEEK. DIURNAL ISOLATED TO
SCATTERED MOUNTAIN SHOWERS WILL RETURN AND INCREASE INTO
TUESDAY...ALONG WITH RISING TEMPERATURES.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
AT KCLT...STORM CURRENTLY OVER THE AIRFIELD WILL MOVE EAST BY 21Z.
CANNOT RULE OUT ANOTHER SHOWER OR STORM BEFORE SUNSET...BUT CHANCE
IS LOW. OTHER THAN VARIABLE WIND GUSTS ASSOCIATED WITH THE
CONVECTION...WINDS SHOULD FAVOR A SW DIRECTION THRU ABOUT 02Z...WITH
A COLD FRONT SHOULD PASS TO THE EAST. THEN WINDS SWITCH TO NW FOR
THE REST OF THE PERIOD...INCREASING TO 6 KT OR MORE BY MIDDAY
WEDNESDAY. CONDITIONS ARE EXPECTED TO BE VFR OTHER THAN WITH THE
TSRA...WITH LINGERING LOW VFR CIGS OVERNIGHT...SCATTERING OUT AFTER
DAYBREAK WEDNESDAY.

ELSEWHERE...CONVECTION IS FAVORING A SUBTLE BOUNDARY ROUGHLY ALONG
THE NC/SC BORDER...WITH ONLY ISOLATED TO SCATTERED SHRA/TSRA
EXPECTED ELSEWHERE THE REST OF THE AFTN. A COLD FRONT WILL EXIT TO
THE EAST EARLY THIS EVENING...WITH DRYING NWLY FLOW TAKING OVER THE
AREA FOR THE REST OF THE PERIOD. MOISTURE WILL LINGER FOR VFR CIGS
MAINLY IN THE NC FOOTHILLS/PIEDMONT...AND MVFR CIGS WORKING UP THE
VALLEY TO KAVL. THERE MAY BE SOME PATCHY FOG AROUND ANY SITES THAT
RECEIVE SOME RAIN THIS AFTN/EVE THEN SEE WINDS GO LIGHT WITH
CLEARING SKIES. BUT OVERALL...NOT EXPECTING MUCH FOG TONIGHT. CLOUDS
SHOULD SCATTER OUT AFTER DAYBREAK WEDNESDAY...AS DRIER AIR FILTERS
IN FROM THE NW.

OUTLOOK...A STRONG UPPER LOW WILL SWING THRU THE AREA WED NIGHT THRU
FRIDAY...AND WILL BRING SHRA AND TSRA MAINLY ACROSS THE NC SITES
BOTH THU AND FRI AFTN.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     MED   73%     MED   76%     HIGH 100%
KHKY       HIGH  89%     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 SCHEDULE TAF ISSUANCE FLIGHT RULE CATEGORY.  COMPLET HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK:

WWW.WEATHER.GOV/GSP/AVIATION

&&

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

&&

$$
SYNOPSIS...HG
NEAR TERM...ARK/RWH
SHORT TERM...HG
LONG TERM...HG
AVIATION...ARK/RWH



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