Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 032348
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
748 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 745 PM...STRONG STORMS STILL ONGOING ALONG A WEAK BOUNDARY
ACROSS THE NC PIEDMONT. EXPECT THESE STORMS TO DISSIPATE WITH THE
LOSS OF HEATING. WILL WAIT TO DROP THE WATCH UNTIL THE THREAT OF
STORMS HAS DIMINISHED. SCATTERED CLOUDS AND DRY CONDITIONS EXPECTED
ELSEWHERE EARLY THIS EVENING.

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 /00Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...LINGERING CONVECTION SHOULD REMAIN NORTH OF THE TERMINAL
THIS EVENING. HOWEVER...OUTFLOW BOUNDARIES FROM THE STORMS COULD
REACH THE AIRFIELD BRIEFLY TURNING THE WINDS NW BEFORE THE MAIN
FRONT MOVES THROUGH BRINGING A PERMANENT WIND SHIFT. OTHERWISE...
EXPECT VFR CONDITIONS WITH SW WIND BECOMING NW EARLY THIS EVENING.
WIND TURNS N OVERNIGHT AND REMAINS THERE UNTIL EARLY AFTERNOON WHEN
MIXING BRINGS A STRONGER WNW WIND. CANNOT RULE OUT SOME LOW END
GUSTS FOR THE AFTERNOON GIVEN THE DEEP MIXING. THERE WILL BE SOME
SCATTERED LOW VFR CLOUDS AROUND THROUGH THE PERIOD...WITH THE
POTENTIAL FOR OFF AND ON MID OR HIGH CLOUD CEILINGS.

ELSEWHERE...DO NOT EXPECT ANY ADDITIONAL CONVECTION AT TAF SITES...
WITH CONVECTION NORTH OF CLT MOVING OUT BEFORE MIDNIGHT. GUSTY WINDS
SHOULD DIMINISH THIS EVENING AFTER A COLD FRONT MOVES THROUGH. DO NOT
EXPECT ANY FOG AT TAF SITES...BUT BRIEF FOG COULD DEVELOP ELSEWHERE
BEFORE DRIER AIR MOVES IN BEHIND THE FRONT. SOME LINGERING LOW VFR
CLOUDS WILL CONTINUE OVERNIGHT. KAVL THE EXCEPTION WHERE MVFR CLOUDS
WILL MOVE IN AS MOISTURE MOVES UP THE VALLEY. THESE CLOUDS SHOULD
SCATTER OUT BEFORE NOON. SW WINDS BECOME NW THIS EVENING...THEN BACK
TO W DURING THE DAY WEDNESDAY. KAVL WILL SEE NNW WINDS THROUGH THE
PERIOD. GUSTY WINDS EXPECTED TO DEVELOP BY AFTERNOON MOST LOCATIONS
AS MIXING DEEP MIXING DEVELOPS.

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...

            23-05Z        05-11Z        11-17Z        17-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     MED   61%     MED   66%     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 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...RWH


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