Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 261725
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
125 PM EDT TUE APR 26 2016

.SYNOPSIS...
OFFSHORE ATLANTIC HIGH PRESSURE WILL PERSIST OVER THE SOUTHEAST
THROUGH MIDWEEK. THEN...A WEAK COLD FRONT WILL ARRIVE FROM THE
NORTHWEST ON THURSDAY. WEAK HIGH PRESSURE WILL RETURN BRIEFLY ON
FRIDAY...AS A LOW PRESSURE SYSTEM APPROACHES FROM THE WEST OVER THE
WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 125 PM...BROKEN CU FIELD HAS DEVELOPED ACROSS THE MOUNTAINS
AND FOOTHILLS...WITH SCT COVERAGE ELSEWHERE. RADAR REMAINS ECHO FREE
FOR THE MOMENT. HAVE SLOWED CONVECTIVE INITIATION ONCE AGAIN...BUT
KEPT OVERALL COVERAGE AS IS. MAXES WILL REACH 5 TO 10 DEGREES ABOVE
CLIMO THROUGHOUT.

THE MESOSCALE MODELS DEVELOP QUITE A BIT OF CONVECTION ALONG THE
BACK DOOR FRONT APPROACHING THROUGH THE VIRGINIAS LATE TODAY THROUGH
TONIGHT...BUT GENERALLY HAVE COVERAGE DIMINISHING AS ANY ATTENDANT
CONVECTION APPROACHES THE NORTHERN TIER OF THE FORECAST AREA
TONIGHT. WILL KEEP ANY LINGERING ISOLATED TO SCATTERED CONVECTION
CONFINED TO THE NORTHERN TIER AND THE MOUNTAINS TONIGHT.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 245 AM TUESDAY...A FLAT UPPER RIDGE WILL HOLD SWAY ACROSS THE
SOUTHEAST STATES DURING THE SHORT TERM...WITH SOME INCREASE IN FLOW
AND VORT ENERGY STREAMING THRU ON THURSDAY. AT THE SFC...HIGH
PRESSURE OFF THE EAST COAST WILL CONTINUE TO SUPPLY LLVL MOISTURE
INTO THE REGION. SO MODELS SHOW INCREASING INSTBY WEDNESDAY
AFTN...WITH THURSDAY LOOKING LIKE THE MOST UNSTABLE DAY. EXPECT BEST
COVERAGE ACRS THE MTNS ON WEDNESDAY...WHERE UPSLOPE AND DIFFERENTIAL
HEATING WILL SUPPLY SOME CONVERGENCE. ON THURSDAY...A WEAK COLD
FRONT IS PROGGED TO ENTER THE AREA IN THE AFTN. SO BETTER COVERAGE
EVEN EAST OF THE MTNS IS EXPECTED. SHEAR WILL BE MARGINAL FOR
ORGANIZING SOME UPDRAFTS THURSDAY...ON THE ORDER OF 30 KTS UP TO 6
KM. SO A SEVERE TSTM OR TWO WILL BE POSSIBLE. TEMPS WILL BE WELL
ABOVE NORMAL ACRS THE ENTIRE AREA...WITH HIGHS IN THE 80S AND LOWS
IN THE 60S ACRS THE PIEDMONT.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 315 AM TUESDAY...DRY NWLY LLVL FLOW AND WEAK CAA WILL DEVELOP
ATOP THE CWFA BEYOND THE FRONT BY DAYBREAK FRIDAY...MAKING FOR A DRY
DAY. TEMPS WILL ACTUALLY BE SLIGHTLY WARMER IN THE LOWER ELEVATIONS
THANKS TO DOWNSLOPE NEGATING THE CAA. HIGHS IN THE MID TO UPR 80S IS
EXPECTED ACRS THE PIEDMONT...AND IN THE UPR 70S TO AROUND 80 IN THE
MTN VALLEYS.

THE DRY WEATHER WILL BE SHORTLIVED...AS MODELS AGREE THAT THE UPPER
RIDGE WILL AMPLIFY AND SHIFT EAST...BRINGING INCREASING DEEP-LAYER
SWLY FLOW ACRS THE REGION. AT THE SFC...DRY HIGH PRES WILL WEDGE SWD
EAST OF THE APPALACHIANS BY SATURDAY MORNING...WITH MODELS STILL IN
DISAGREEMENT ON HOW FAST MOISTURE RETURNS ATOP THE WEDGE. THE GFS
HAS CLOUDS AND QPF INCREASING BY SATURDAY EVENING...WHILE THE ECMWF
DOES NOT HAVE MUCH POP UNTIL SUNDAY EVENING. SO WILL CONTINUE TO
ADVERTISE A COOLING TREND WITH GRADUAL INCREASE IN CLOUDS AND
POPS...WITH HIGHEST POPS ON SUNDAY. MOIST UPGLIDE WILL CONTINUE
THRU MONDAY AS LLVL FLOW TURNS OUT OF THE SW. SO WILL CONTINUE WITH
SOLID CHANCE POPS WITH NEAR NORMAL HIGH TEMPS AND ABOVE NORMAL LOWS.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE...SAT PIX AND OBS SHOW MAINLY SCT CU FIELD
ACROSS THE PIEDMONT WITH BKN COVERAGE OVER THE MOUNTAINS AND
FOOTHILLS. HAVE GONE WITH THESE TRENDS INTO EARLY EVENING WHEN LOWER
VFR CLOUDS BEGIN DISSIPATING AND BKN MID AND HIGH CLOUDS MOVE IN.
GIVEN THE CURRENT RADAR TRENDS...HAVE ELIMINATED THE VCSH AT KHKY
AND BACKED UP THE TIMING OF VCTS AT KAVL. EXPECT VFR CONDITIONS MOST
OF THE NIGHT WITH SOME LINGERING LOWER VFR CLOUDS. KAND THE
EXCEPTION WITH MVFR FOG DEVELOPING TOWARD DAYBREAK. HAVE KEPT THE
LOW VFR AT FEW AFTER DAYBREAK...BUT COULD REACH SCT OR EVEN BKN
ACROSS THE NORTH WHERE MOISTURE IS BETTER. HAVE ADDED PROB30 AT KAVL
AND KHKY BY NOON AS THOSE LOCATIONS HAVE THE BEST CHANCE OF SEEING
ANY CONVECTION THAT EARLY. S TO SW WINDS WITH LOW END GUSTS BECOME
LIGHT S TO SW THIS EVENING. EXPECT SW WINDS AGAIN AFTER DAYBREAK
WEDNESDAY. KAVL THE EXCEPTION CALM WIND OVERNIGHT AND NNW WIND AFTER
DAYBREAK.

OUTLOOK...INSTABILITY WILL INCREASE ACROSS THE REGION WEDNESDAY
AFTERNOON AS A BACK DOOR FRONT STALLS TO THE NORTH. PRECIPITATION
CHANCES AND ASSOCIATED RESTRICTIONS SHOULD INCREASE INTO THURSDAY
AHEAD OF A COLD FRONT APPROACHING FROM THE NORTHWEST. SOME DRYING IS
EXPECTED ON FRIDAY BEFORE UNSETTLED WEATHER RETURNS FROM THE WEST
OVER THE WEEKEND.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
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 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...ARK
NEAR TERM...HG/RWH
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...RWH



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