Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 252344
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
744 PM EDT MON APR 25 2016

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO SLIDE OFFSHORE TONIGHT AND
TOMORROW...ALLOWING MOIST SOUTHWESTERLY FLOW TO OVERSPREAD THE
REGION BY MIDWEEK. A WEAK COLD FRONT WILL CROSS THE AREA FROM THE
WEST ON THURSDAY. IN THE FRONTS WAKE...WEAK HIGH PRESSURE
WILL RETURN FOR FRIDAY AND LINGER INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TUESDAY/...
AS OF 745 PM...SHOWERS NEAR THE BLUE RIDGE HAVE ALREADY
DISSIPATED...SO THE PRECIP CHANCES WILL BE REMOVED IN SHORT ORDER.
EXPECT THE CUMULUS CLOUDS TO FOLLOW A SIMILAR PATTERN. TEMP/DEWPT
TRENDS LOOK FINE.

EXPECT FLAT RIDGING TO REMAIN IN PLACE OVER THE SE CONUS AS ONE
SHORT WAVES MOVES EAST OVER THE MID-ATLANTIC STATES AND ANOTHER
MOVES INTO THE OH VALLEY. AT THE SURFACE...THE CENTER OF HIGH
PRESSURE MOVES OUT INTO THE ATLANTIC KEEPING A SOUTH TO
SOUTHWESTERLY FLOW OVER THE AREA. THIS MOIST FLOW MAY LEAD TO SOME
LOW CLOUDS FORMING ACROSS THE AREA TOWARD DAYBREAK...MAINLY IN THE
SAVANNAH R BASIN...WHICH SHOULD LIFT AND/OR SCATTER OUT THROUGH THE
MORNING TUESDAY. MODERATE INSTABILITY DEVELOPS OVER THE MOUNTAINS
AND I-40 CORRIDOR DURING THE AFTERNOON. INSTABILITY REMAINS WEAKER
ACROSS THE REST OF THE AREA...WITH EVEN A WEAK CAP REMAINING IN
PLACE. THEREFORE...HAVE LIMITED DIURNAL CONVECTION CHANCES TO THE
AREAS WITH GREATER INSTABILITY. LOWS TONIGHT AND HIGHS TUESDAY WILL
BE UP TO 10 DEGREES ABOVE NORMAL.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM MONDAY...TUESDAY EVENING BEGINS WITH A PATTERN OF WEAK
ZONAL FLOW ALOFT WITH A SMALL RIDGE WEST OF THE AREA AND AN ANTICYCLONIC
SURFACE HIGH OFF THE ATLANTIC COAST.  BL MOISTURE IS INCREASING ON
SW ADVECTION OF GULF MOISTURE AROUND THE SURFACE HIGH WHICH WILL
COMBINE WITH CONVERGENCE OVER THE MOUNTAINS ALONG A WEAK SURFACE
BOUNDARY TO PRODUCE SHOWERS AND THUNDERSTORMS IN THAT AREA TUESDAY
NIGHT.  AS UPPER RIDGE MOVES OVER THE AREA...ACTIVITY WILL DECLINE
WEDNESDAY MORNING...BUT APPROACH OF A MUCH MORE SIGNIFICANT UPPER
SYSTEM OUT WEST WILL INCREASE FORCING AND RESULTANT SHOWER ACTIVITY
WEDNESDAY EVENING THROUGH THURSDAY.  IMPROVING BL MOISTURE PERSISTS
ALL DAY WED. AND THURS. WHICH WILL PROGRESSIVELY INCREASE CONVECTIVE
INSTABILITY.  LI REACHES -2 TO -4 TUESDAY AFTERNOON AND -3 TO -6 ON
THURSDAY.  DEEP LAYER SHEAR IS NOT PARTICULARLY
STRONG...HOWEVER...WITH BULK SHEAR TO ONLY 20KTS SO SEVERE STORMS
ARE NOT ANTICIPATED...BUT THUNDERSTORMS ARE EXPECTED WITH THE
GREATEST COVERAGE THURSDAY AFTERNOON.  WARM ADVECTION PATTERN WILL
KEEP TEMPERATURES 5 TO 10 DEGREES ABOVE NORMAL...SURFACE WINDS OF 5
TO 10 KTS WITH A PERSISTENT SOUTHWESTERLY DIRECTION.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 230 PM MONDAY...THURSDAY NIGHT...MEDIUM RANGE MODELS INDICATE
THAT A STATIONARY FRONT WILL RUN WEST TO EAST ACROSS THE CWA DURING
THE MORNING HOURS. I WILL INDICATE CHC TO SCHC POPS THROUGH THE AM
HOURS...THEN DRYING DURING THE DAYLIGHT HOURS. A S/W WILL PASS NORTH
OF THE FORECAST AREA...EXPECTED TO HAVE LITTLE INFLUENCE OVER FA.
HIGH TEMPERATURES ARE FORECAST TO RANGE FROM AROUND 80 DEGREES
WITHIN THE MTN VALLEYS TO MID TO UPPER 80S ACROSS THE FOOTHILLS AND
PIEDMONT. FRIDAY NIGHT THROUGH SATURDAY MORNING...MID LEVEL RIDGING
WILL BUILD OVER THE SOUTHERN APPALACHIANS AS SFC HIGH PRESSURE
RIDGES FROM THE NORTH. TEMPERATURES ARE FORECAST TO COOL TO AROUND
CLIMO UNDER INCREASING CLOUD COVER. POPS WILL REMAIN LIMITED TO SCHC
EAST CHC WEST.

SUNDAY THROUGH MONDAY...THE PATTERN IS FORECAST TO FEATURE LINGERING
RIDGED HIGH PRESSURE FROM THE NORTH. TO THE WEST...A MID LEVEL S/W
WILL RIPPLE ACROSS THE MS RIVER VALLEY EARLY NEXT WEEK. THE PASSAGE
OF THE S/W WILL SUPPORT THE FORMATION OF THE SFC LOW ACROSS THE
TN/AL/GA...RESULTING IN A WARM FRONT TO SQUEEZE THE W. CAROLINA
WEDGE NORTH. THIS PATTERN APPEARS RIPE FOR SHOWERS AND THUNDERSTORMS
BOTH DAYS. TEMPERATURES MAY RANGE FROM SLIGHTLY BELOW NORMAL SUNDAY
TO NEAR NORMAL ON MONDAY.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
AT KCLT AND ELSEWHERE...CUMULUS STARTING TO FADE NOW THAT HEATING IS
DIMINISHING AT DUSK. SHOULD BE QUIET OVERNIGHT WITH MAINLY CIRRUS.
STEADY S TO SW WIND AT FIRST SHOULD DIMINISH TO 6 KT OR SO FOR THE
OVERNIGHT. THE BIG QUESTION FOR THIS PERIOD WILL BE THE EXTENT/
AMOUNT OF LOW LEVEL MOISTURE THAT RETURNS FROM THE S. PRESENT
INDICATION IS THAT BEST CHANCE FOR RESTRICTIONS WILL BE THE SAVANNAH
R BASIN...WHICH IS CLOSER TO THE FCST MOISTURE PLUME. THIS COULD
AFFECT KAND/KGMU WITH AN MVFR CEILING OR VISIBILITY RIGHT AROUND
DAYBREAK. THE LATEST GUIDANCE IS NOT NEARLY AS FAVORABLE FOR A LOW
CLOUD CEILING AT KCLT. WILL FOLLOW THE GUIDANCE TREND AND KEEP SKY
CONDITION SCATTERED AT KCLT. SW WIND PICKS BACK UP AFTER DAYBREAK.
KAVL THE EXCEPTION WITH W TO NW WIND AFTER DAYBREAK. THERE COULD BE
A FEW THUNDERSTORMS OVER THE NC MOUNTAINS IN THE MID/LATE
AFTERNOON...THUS THE PROB30 AT KAVL.

OUTLOOK...INSTABILITY WILL INCREASE ACROSS THE REGION TUESDAY NIGHT
THROUGH WEDNESDAY AS A COLD FRONT APPROACHES FROM THE NORTH.
PRECIPITATION CHANCES AND ASSOCIATED RESTRICTIONS WILL INCREASE INTO
THURSDAY AHEAD OF A COLD FRONT APPROACHING FROM THE NORTHWEST...WITH
UNSETTLED WEATHER POSSIBLE INTO FRIDAY.

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  94%     LOW   58%
KAVL       HIGH 100%     HIGH 100%     MED   61%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH  94%     LOW   58%
KAND       HIGH 100%     HIGH 100%     LOW   44%     LOW   58%

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...JPT
NEAR TERM...PM/RWH
SHORT TERM...WJM
LONG TERM...NED
AVIATION...PM



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