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Area Forecast Discussion

316
FXUS62 KGSP 252102
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
502 PM EDT FRI JUL 25 2014

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN ACROSS THE AREA THROUGH THE WEEKEND.
ANOTHER COLD FRONT IS EXPECTED TO REACH THE AREA FROM THE NORTHWEST
BY EARLY MONDAY. HIGH PRESSURE WILL REGAIN CONTROL ON TUESDAY...
LASTING THROUGH AT LEAST MID-WEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 440 PM EDT...THE LATE AFTERNOON CUMULUS FIELD CONTINUES TO
SHOW SOME MODERATE DEVELOPMENT MAINLY ALONG THE EASTERN ESCARPMENT
OF THE MTNS. LAPS AND MODEL PROFILES SHOW MODEST POTENTIAL FOR ISOLD
CONVECTIVE DEVELOPMENT IN THIS AREA AND ALSO IN THE BETTER DEWPOINTS
OF THE EXTREME SE PIEDMONT WHERE OUTFLOWS FROM MIDLANDS ACTIVITY
COULD ARRIVE...SO LOW END POPS WILL BE MAINTAINED FOR A COUPLE HOURS
MORE.

OTHERWISE...ANY CONVECTION SHOULD DIMINISH FAIRLY QUICKLY THIS
EVENING. LOW LEVEL MOISTURE REMAINS SUFFICIENT FOR DEVELOPMENT OF
VALLEY FOG AND LOW STRATUS LATE TONIGHT/EARLY SATURDAY. THERE COULD
BE ANOTHER ROUND OF LOW STRATUS OUTSIDE THE MTNS...ALTHOUGH VEERING
LOW LEVEL FLOW MAKES THAT LESS OF POSSIBILITY SAT MORNING. MIN TEMPS
SHOULD SETTLE VERY CLOSE TO CLIMO.

SATURDAY...FORECAST SOUNDINGS ARE CAPPED UNDER THE INFLUENCE OF
RISING HEIGHTS ALOFT...AS A RIDGE AXIS ASSOCIATED WITH THE
SUB-TROPICAL HIGH OVER THE GREAT PLAINS NOSES ITS WAY TOWARD THE
SOUTHEAST COAST. AS A RESULT...THERE IS LITTLE TO NO MODEL QPF
RESPONSE ACROSS THE AREA SATURDAY AFTERNOON...AND A DRY FORECAST
WILL BE MAINTAINED AS INHERITED. OTHERWISE...TEMPS WILL WARM
NOTICEABLY FROM TODAY/S READINGS...WITH MAXES EXPECTED TO REACH THE
LOWER 90S IS MOST LOCATIONS EAST OF THE MTNS...AND MID/UPPER 80S
EXPECTED IN THE MTN VALLEYS.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 100 PM FRI...BROADLY CYCLONIC UPPER LEVEL FLOW WILL CONTINUE
ACRS THE ERN HALF OF THE CONUS SATURDAY NIGHT AND SUNDAY...BEFORE
BEGINNING TO AMPLIFY MONDAY AS A POTENT SHORTWAVE MOVES THRU THE
GREAT LAKES. A COLD FRONT ACCOMPANYING THE TROUGH WILL MOVE THRU THE
OHIO VALLEY SUNDAY...WITH MOST GUIDANCE INDICATING A PASSAGE ACRS THE
SRN APPALACHIANS EARLY MONDAY...BUT STILL IN PLACE TO AFFECT THE
PIEDMONT THAT AFTN.

SATURDAY NIGHT SHOULD BE QUIET WITHIN OUR CWFA...AND SUNDAY SHOULD
START OFF QUIET. VARIOUS GUIDANCE SOURCES CONTINUE TO SHOW NOTABLE
DIFFERENCES IN QPF RESPONSE TO DIURNAL DESTABILIZATION. GFS IS
ESSENTIALLY THE DRIEST MODEL...WITH A WARM LAYER ALOFT CAPPING OFF
CONVECTION. OPNL NAM ALSO INDICATES SOME DEGREE OF CAPPING THOUGH IT
WEAKENS LATE IN THE DAY...PARTICULARLY OVER THE MTNS. SREF MEMBERS
ARE FAIRLY EVENLY SPREAD BETWEEN STRONG CAPPING AND FREE CONVECTION.
LAPSE RATES ABOVE THE WARM LAYER ARE DECENT...WHICH IN CONJUNCTION
WITH SFC TEMPS/DEWPTS SLIGHTLY ABOVE NORMAL MEANS UNCAPPED PARCELS
WILL BE SOMEWHAT MORE UNSTABLE THAN USUAL. THIS WOULD BE CONCURRENT
WITH STRENGTHENING UPPER FLOW AHEAD OF THE DIGGING TROUGH...SO IF THE
TIMING IS RIGHT THERE COULD BE A SEVERE THREAT. THIS BECOMES MORE OF
A CONCERN OVERNIGHT IN THE MTNS WHERE SOME PROG SOUNDINGS ARE
UNCAPPED FOR NEAR-SURFACE PARCELS AS SHEAR RISES TO 40-50 KT. SPC HAS
ALREADY INCLUDED A PORTION OF OUR MTNS IN A SLIGHT RISK ON THE DAY 3
OTLK VALID THRU 12Z MON...WITH MOST OF THE REST OF THE CWFA WITHIN
THE 5 PERCENT CONTOUR. REGARDLESS OF ANY CONVECTION...WINDS WILL
BEGIN TO BECOME RATHER GUSTY IN THE HIGHER ELEVATIONS SUNDAY NIGHT.
THIS WILL CONTINUE MONDAY EVEN POST-FROPA.

COOLER AND DRIER AIR ARE PROGGED TO BEGIN FILTERING INTO THE MTNS BY
MIDDAY MONDAY...AND THRU THE PIEDMONT BY 00Z TUE IN THE WAKE OF THE
FRONT. THERE STILL APPEARS TO BE TIME FOR DESTABILIZATION AHEAD OF
THE WIND SHIFT LINE SO FRONTAL ENHANCEMENT TO TSTM CHANCES APPEARS
LIKELY AT LEAST ALONG AND SOUTH OF I-85 IF NOT UP INTO THE FOOTHILLS.
HODOGRAPHS IN THIS AREA WILL BE RATHER LONG WITH H5 FLOW NEARING 50
KT INDICATING A SUPERCELL RISK IN OUR AREA. SPC IS CURRENTLY
HIGHLIGHTING AREAS OF ERN NC/VA ON THE DAY 4 GRAPHIC BUT THE RISKS
THEY DESCRIBE APPEAR TO BE PRESENT IN OUR ERN/SERN ZONES AS WELL.
MONDAY AFTN MAX TEMPS IN THE MTNS REFLECT THE COOL AIRMASS THAT WILL
REMAIN OVER THE REGION THRU MOST OF NEXT WEEK...BEING 2 OR 3
CATEGORIES BELOW NORMAL. THE PIEDMONT APPEARS TO STILL BE CAPABLE OF
MAXES NEAR NORMAL.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 2 PM EDT FRIDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
TUESDAY WITH A SIGNIFICANT UPPER TROF DIGGING DOWN OVER THE EASTERN
CONUS WHILE AN EQUALLY STEEP UPPER RIDGE IS IN PLACE OVER THE WEST.
NO MAJOR PATTERN CHANGES ARE EXPECTED AS THIS TROF WILL REMAIN
LARGELY IN PLACE THRU DAY 7 WITH SOME DEAMPLIFICATION LIKELY ON DAYS
6 AND 7.

AT THE SFC...A FAIRLY STRONG WARM SEASON COLD FRONT WILL BE MOVING
THRU THE FCST AREA LATE MON/EARLY TUES WITH CONSIDERABLY COOLER AND
DRIER AIR SPREADING OVER THE CAROLINAS ON TUES. BEHIND THE DEPARTING
FRONT CANADIAN HIGH PRESSURE WILL KEEP NLY FLOW OVER THE AREA THRU
WED AS IT GRADUALLY SLIDES SOUTHEASTWARD. BY THURS...BNDRY LYR FLOW
SHOULD BE PRETTY WEAK AND POSSIBLY BECOME VRB FOR MOST OF THE
DAY/EVENING. ON FRI...THE LONG RANGE MODELS VEER THE LOW LVL FLOW
MORE FROM THE EAST TO NE AND MOVE A LARGE PLUME OF DEEPER LYR
MOISTURE OVER THE CWFA FROM THE SOUTH. THIS WILL PROVIDE OUR BEST
OPPORTUNITY FOR WIDESPREAD SHOWERS AND TS IN THE MEDIUM RANGE.
OTHERWISE...I EXPECT DRY CONDITIONS WITH UNSEASONABLY COOL TEMPS
THRU DAY 7.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE EXCEPT KAVL...SCT TO BKN VFR CUMULUS WILL
CONTINUE UNTIL SUNDOWN. STILL EXPECT THAT ANY TSTMS WILL DEVELOP
WELL SE OF KCLT AND POSSIBLY ALONG THE IMMEDIATE MTN ESCARPMENT WEST
OF THE FOOTHILL SITES LATE THIS AFTN. NOTHING WILL NEED TO BE
MENTIONED IN THE TAFS. EXPECT MAINLY LIGHT SE WINDS...WHICH MIGHT GO
CALM AT TIMES TONIGHT. WITH LOW LEVEL MOISTURE REMAINING IN
ABUNDANCE...THERE IS A CHANCE FOR BR AND POSSIBLY A RETURN OF LOW
STRATUS TOWARD DAYBREAK SATURDAY. HOWEVER...WITH LOW LEVEL FLOW
EXPECTED TO VEER TOWARD THE SW...THE PROBABILITY OF LOW CLOUDS
DEVELOPING APPEARS A BIT LOWER THAN WHAT WAS SEEN THIS MORNING...SO
VFR SKY CONDITIONS WILL BE MAINTAINED. WITH THE LATEST UPDATE...WILL
HINT AT LOWER CLOUDS AT KCLT WITH A SCT MENTION GIVEN THE PERSISTENT
RESTRICTIONS IN NAM MOS.

AT KAVL...CANNOT RULE OUT A SHOWER OR THUNDERSTORM PASSING NEAR THE
TERMINAL LATE THIS AFTERNOON...BUT COVERAGE SHOULD BE TOO LIMITED TO
WARRANT A VCTS/VCSH MENTION. OTHERWISE...PERIODS OF LOW VFR CIGS CAN
BE EXPECTED THROUGH THE AFTERNOON. PLENTIFUL LOW LEVEL MOISTURE
MEANS FOG AND PERHAPS LOW STRATUS ARE A GOOD BET TONIGHT...AND HAVE
STARTED THINGS OFF WITH A 3SM/SCT004 MENTION AFTER 06Z FOR NOW.

OUTLOOK...GENERALLY VFR THROUGH SUNDAY MORNING...EXCEPT FOR POSSIBLY
MORNING MTN VALLEY FOG. SCT THUNDERSTORMS MAY RETURN TO THE FORECAST
AREA FOR SUNDAY AFTERNOON THROUGH MON...AS ANOTHER COLD FRONT
APPROACHES AND THEN MOVES THROUGH THE AREA BY MON NIGHT. VFR
CONDITIONS WILL THEN LINGER THROUGH MID WEEK.

CONFIDENCE TABLE...

            21-03Z        03-09Z        09-15Z        15-21Z
KCLT       MED   70%     HIGH  99%     HIGH  88%     MED   72%
KGSP       MED   67%     HIGH 100%     HIGH  97%     HIGH  86%
KAVL       MED   71%     LOW   58%     MED   62%     HIGH 100%
KHKY       MED   68%     HIGH  86%     MED   76%     MED   72%
KGMU       HIGH 100%     HIGH 100%     HIGH  97%     HIGH 100%
KAND       HIGH 100%     HIGH  97%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

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

&&

$$
SYNOPSIS...JDL
NEAR TERM...HG/JDL
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...HG/JDL






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