Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 021739
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
139 PM EDT WED SEP 2 2015

.SYNOPSIS...
A WEAK PRESSURE PATTERN WILL LINGER ATOP THE REGION FOR THE REST OF
THE WORKWEEK. LATE SUMMER WARMTH AND DAILY THUNDERSTORM CHANCES WILL
BE THE MAIN FEATURES OF INTEREST. A BACK DOOR COLD FRONT IS EXPECTED
TO PUSH ACROSS THE REGION ON FRIDAY FOLLOWED BY A COOL AND MOIST
AREA OF HIGH PRESSURE THIS WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM...MADE SEVERAL MINOR ADJUSTMENTS TO GRIDS BASED ON
OBSERVATIONS. PRETTY THIN CIRRUS SHIELD OUT THERE...OTHERWISE JUST
SOME ISOLATED CU DEVELOPING OVER THE MOUNTAINS. REDUCED SKY COVER
ACCORDINGLY. NEW CAM/HIRES GUIDANCE DELAYING CONVECTIVE INITIATION
BY A COUPLE OF HOURS SO LOWERED POPS THIS MORNING AND PULLED BACK
SOMEWHAT ON AREAL EXTENT. TEMPERATURES LOOK PRETTY GOOD BUT ARE
RISING A LITTLE MORE RAPIDLY THIS MORNING THAN EXPECTED...UPDATED
HOURLY TRENDS AND WILL MONITOR IN CASE HIGHS NEED TO BE ADJUSTED.

AS OF 630 AM...BROAD SUBTROPICAL RIDGE OVER THE SERN CONUS WILL
WEAKEN TODAY AS A SHORTWAVE...NOW CENTERED OVER OHIO...DRIFTS
TOWARD THE MID-ATLANTIC COAST. THE LOW LEVEL FLOW WILL CONTINUE
TO BE PRIMARILY UNDER THE INFLUENCE OF THE RIDGE...MOIST AND
SWLY. WHILE THE BETTER DYNAMIC FORCING AHEAD OF THE SHORTWAVE
WILL BE JUST TO OUR NORTHEAST THE FALLING HEIGHTS ASSOCIATED WITH
IT WILL PRODUCE MORE FAVORABLE BUOYANCY PROFILES THAN THE PAST
COUPLE OF DAYS. CONVECTIVE INITIATION IS EXPECTED ALONG THE BLUE
RIDGE...PRODUCING WIDELY SCTD TSTMS...BUT ISOLD STORMS ARE EXPECTED
TO BE ABLE TO PROPAGATE MORE OR LESS TO THE I-85 CORRIDOR. CAPE
VALUES FROM THE NAM DO SEEM AWFULLY HIGH...WITH MORE MODEST VALUES
ON THE GFS. HOWEVER WITH LATEST CAM GUIDANCE MAINLY SHOWING SPARSE
COVERAGE FOR THE AFTN AND WITH BUFKIT PROFILES NOT LOOKING THAT
GREAT /ASIDE FROM THE NAM/...I HAVE LIMITED POPS TO 30 PERCENT WITH
THIS UPDATE. WEAK SHEAR BUT RELATIVELY DRY MID-UPPER LEVELS WOULD
SUGGEST THE PRIMARY IMPACTS WILL BE GUSTY WINDS. SEVERE WEATHER
IS NOT ANTICIPATED.

AS THE WAVE PLUNGES SWD INTO ERN VA/NC TONIGHT...WINDS WILL VEER TO
NWLY ACRS MOST OF THE CWFA BRINGING IN SLIGHTLY DRIER CONTINENTAL
AIR BY THU MRNG. SOME CLOUD COVER WILL ACCOMPANY THE ACCOMPANYING
BOUNDARY THOUGH NO PRECIP IS EXPECTED TO RESULT. SLIGHTLY WARMER
MIN TEMPS 2-4 DEGREES ABOVE NORMAL ARE THUS FCST.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
AS OF 315 AM WEDNESDAY...ON THURSDAY...H5 RIDGE BUILDS OVER THE
CENTRAL CONUS AS A BROAD TROUGH AMPLIFIES OVER THE WESTERN ATLANTIC.
AT THE SFC...HIGH PRESSURE CENTERED OVER THE OHIO RIVER VALLEY WILL
BUILD ACROSS THE SOUTHERN APPALACHIANS...RESULTING IN LIGHT
NORTHWEST FLOW. PROVIDED THE LIGHT DOWNSLOPE FLOW...HIGH
TEMPERATURES ARE FORECAST TO RANGE FROM THE 91 TO 94 EAST OF THE
MTNS...WITH UPPER 80S WITHIN THE MTN VALLEYS. FORECAST SOUNDINGS
INDICATE A DEEP INVERTED-V PROFILE...AND MILD TEMPS AROUND
H7...YIELDING WEAK CAPE ACROSS THE REGION. I WILL FORECAST CHC POPS
ACROSS THE RIDGES WITH SCHC POPS EAST.

ON FRIDAY...THE H5 RIDGE WILL BUILD ACROSS THE GREAT LAKES REGION
WITH A BROAD WEAKNESS ACROSS THE SOUTHEAST CONUS. A 1025+MB HIGH IS
FORECAST TO DEVELOP ACROSS THE NEW ENGLAND STATES...RIDGING
SOUTHWEST ACROSS THE ATLANTIC STATES. A BACK DOOR COLD FRONT IS
EXPECTED TO REACH THE PIEDMONT AND FOOTHILLS DURING THE DAYLIGHT
HOURS. THE COMBINATION OF WIDESPREAD WEAK INSTABILITY AND A SFC
BOUNDARY SHOULD TRIGGER SCT SHRA AND TSRA...ESPECIALLY NEAR THE EAST
FACING SLOPES. HIGH TEMPERATURES SHOULD RANGE 3 TO 4 DEGREES BELOW
THURSDAY/S VALUES.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 100 PM WEDNESDAY...THE LATEST MEDIUM RANGE GUIDANCE SUPPORTS
THE GOING THINKING OF SFC RIDGING CONTINUING TO NOSE SSWD INTO THE
CWFA THROUGH SUNDAY. THE PROGGED PRESSURE GRADIENT LOOKS SIMILAR TO
SATURDAY...BUT THINKING CLOUDS WILL BE A TAD THINNER WITH MAXIMUM
TEMPERATURES A HAIR WARMER. WITH SFC PRESSURES FCST TO RISE ON LABOR
DAY MONDAY...PROGRESSIVELY LESS CLOUD COVER AND MAX TEMPERATURES
CLIMBING TOWARD CLIMO IS EXPECTED. THE INHERITED CLIMO RANGE...
DIURNALLY ENHANCED DEEP CONVECTIVE CHANCES WILL REMAIN AS IS.
BACK TO MORE TYPICAL LATE SUMMER CONDITIONS ON TUESDAY FEATURING
TEMPERATURES AND POP NEAR CLIMO WITH AN INCREASE IN RETURN FLOW
PROMPTING GREATER TSTM CHANCES FOR THE NEW DAY 7.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...SFC HIGH PRESSURE WILL REMAIN IN CONTROL
TODAY...BUT A WEAK SHORTWAVE WILL DRIFT FROM THE SOUTHERN
APPALACHIANS TO THE MID-ATLANTIC COAST TONIGHT...WITH ANOTHER WEAK
SHORTWAVE PUSHING ACROSS NORTHERN GEORGIA INTO SOUTH CAROLINA EARLY
THURSDAY. THE TWO OF THESE COMBINED WILL ALLOW FOR ISOLATED
CONVECTION TO FORM THIS AFTERNOON BUT NOT ENOUGH TO MENTION IN THE
TAFS. SHOULD SEE AN INCREASE IN LOW VFR CLOUDINESS ESPECIALLY
OVERNIGHT. WSW WINDS AT TAF TIME AT ALL BUT KAVL /NW THERE/ WILL
VEER AND SHIFT TO WNW BY 00Z OR SO...AND AROUND TO N /MAINLY CALM/
OVERNIGHT. SHOULD NOT SEE ANY RESTRICTIONS AT THE TAF SITES THURSDAY
MORNING DUE TO DRIER SURFACE AIR BUILDING IN.

OUTLOOK...A PATTERN OF DIURNAL ISOLATED/WIDELY SCT SHOWERS
AND THUNDERSTORMS IS EXPECTED TO CONTINUE THRU THE END OF THE
WORK WEEK. BY THE WEEKEND...A MOIST EASTERLY FLOW IS EXPECTED TO
DEVELOP...BRINGING BETTER CHANCES FOR SHOWERS AND RESTRICTIONS. LOW
CLOUDS AND FOG WILL BE POSSIBLE EACH NIGHT IN THE MOUNTAIN VALLEYS.

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  83%
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 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

&&

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

&&

$$
SYNOPSIS...NED
NEAR TERM...TDP/WIMBERLEY
SHORT TERM...NED
LONG TERM...CSH
AVIATION...TDP



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