Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 252115
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
515 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 515 PM...FINALLY SEEING A FEW SHOWERS POP NEAR THE BLUE
RIDGE...IN NC AT THIS TIME. THE FCST ALREADY ACCOUNTS FOR THIS...SO
NO CHANGES ARE NECESSARY. TEMP/DEWPT TRENDS LOOK FINE.

CONVECTION WILL TAPER OFF QUICKLY THIS EVENING WITH LOSS OF HEATING.
EXPECT THE CUMULUS CLOUDS TO FOLLOW A SIMILAR PATTERN.

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 WILL LEAD TO LOW
CLOUDS FORMING ACROSS THE AREA TOWARD DAYBREAK...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 /21Z MONDAY THROUGH SATURDAY/...
AT KCLT AND ELSEWHERE...VFR CU SPREADING ACROSS THE AREA WITH
AFTERNOON HEATING. CANNOT RULE OUT A BRIEF CEILING THIS AFTERNOON
BUT KAVL MOST LIKELY TO SEE ONE. CU SHOULD DIMINISH THIS EVENING
WITH LOSS OF HEATING. HOWEVER...EXPECT MVFR CLOUDS TO REDEVELOP
TOWARD DAYBREAK GIVEN THE CONTINUED LOW LEVEL MOISTURE AND SOUTHERLY
FLOW...ALONG WITH A WEAK LOW LEVEL INVERSION. SHOULD SEE BKN MVFR
MOST LOCATIONS BY DAYBREAK WITH CLOUDS LIFTING OR SCATTERING OUT BY
15Z. KAND THE ONLY TAF SITE TO LIKELY SEE AN VSBY RESTRICTIONS.
EXPECT SCT LOW VFR TO LINGER INTO EARLY AFTERNOON. S TO SW WIND WITH
OCCASIONAL LOW END GUSTS THIS AFTERNOON WILL DIMINISH THIS EVENING.
SW WIND PICKS BACK UP AFTER DAYBREAK. KAVL THE EXCEPTION WITH NNW
WIND AFTER DAYBREAK.

OUTLOOK...INSTABILITY WILL INCREASE ACROSS THE REGION TUESDAY
AFTERNOON THROUGH WEDNESDAY AS A BACK DOOR COLD FRONT APPROACHES
FROM THE NORTH. PRECIPITATION CHANCES WILL INCREASE INTO THURSDAY
AHEAD OF A COLD FRONT TO THE NORTHWEST...WITH UNSETTLED WEATHER
POSSIBLE INTO FRIDAY.

CONFIDENCE TABLE...

            21-03Z        03-09Z        09-15Z        15-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH  98%     LOW   57%
KAVL       HIGH 100%     HIGH 100%     MED   61%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH  98%     MED   62%
KAND       HIGH 100%     HIGH 100%     LOW   47%     MED   67%

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...RWH



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