Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 051847
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
247 PM EDT SUN JUL 5 2015

.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL CROSS THE CENTRAL
APPALACHIANS TONIGHT...WITH SLIGHT DRYING ARRIVING FROM THE WEST FOR
MONDAY. LOW LEVEL MOISTURE WILL REMAIN THROUGH THE WEEK...WITH A
RETURN TO A MORE NORMAL PERIOD OF SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS EACH DAY OF THE WEEK. A COLD FRONT WILL APPROACH FROM
THE NORTHWEST TOWARD NEXT WEEKEND.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 215 PM EDT...SATELLITE IMAGERY AND THE LATEST RAP ANALYSIS
SHOW THE CLOSED 500 MB LOW CENTER OVER ERN KY THIS AFTERNOON.
VORTICITY MAXIMA ROUNDING THIS SYSTEM ARE MOVING ACROSS THE SRN
APPALACHIANS AND PROVIDING SOME TRIGGERING FOR SHRA/TSRA THIS
AFTERNOON. THE UPPER LOW WILL SLOWLY FILL AND LIFT NE TONIGHT...WITH
THE ASSOCIATED TROUGH AXIS MOVING EASTWARD INTO THE CENTRAL
APPALACHIANS. DESPITE THE APPROACHING UPPER TROUGH...850 TO 500 MB
LAPSE RATES ARE A RATHER MODEST 5 TO 6 DEG C/KM. HOWEVER...SBCAPE
VALUES HAVE BUBBLED UP TO 1500 TO 2000 J/KG ALONG THE NRN TIER AND
OVER THE ERN PIEDMONT...SO AT LEAST SCATTERED THUNDERSTORMS SHOULD
FORM AMONG THE MORE NUMEROUS SHOWERS GIVEN THE IMPROVING UPPER
SUPPORT. RESIDUAL SHOWERS MAY LINGER ALONG THE WESTERN MTNS IN LOW
LEVEL WESTERLY UPSLOPE FLOW OVERNIGHT...EVEN AFTER ANY DPVA ALOFT
HAS PASSED. THE CURRENT FFA WILL REMAIN IN PLACE THROUGH 00Z. THE
NORTHERN MOUNTAINS AND FOOTHILLS COULD SEE PERIODS OF HEAVY RAIN
THIS AFTN/EVENING...BUT NOT ENOUGH TO WARRANT EXPANSION/EXTENSION OF
THE WATCH.

THE UPPER TROUGH WILL MOVE SLOWLY EAST ON MONDAY...WITH MORE OF THE
FORECAST AREA GETTING INTO AN NVA REGION THROUGH THE DAY. WITH LESS
CLOUDS AND MORE HEATING...CONVECTION MAY DEVELOP EASTWARD OFF THE
BLUE RIDGE MONDAY AFTN...ESPECIALLY WITH LOW LEVEL CONVERGENCE
FORMING ALONG THE ERN SLOPES AND IN A LEE TROUGH. LAPSE RATES
STEEPEN A BIT MONDAY AFTERNOON...BUT WARM AIR ALOFT IN PROFILES
SHOULD LIMIT CAPE SOMEWHAT. 850 TO 500 MB LAPSE RATES SHOULD STILL
MANAGE TO REACH 6.5 DEG C/KM...AND WITH MID LEVEL DRY AIR WRAPPING
IN...A GENERAL TSTM THREAT WITH LOCALLY GUSTY WINDS SHOULD ARISE.
TEMPS WILL WARM BACK CLOSE TO CLIMO.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AT 230 PM EDT SUNDAY...ON MONDAY EVENING A FILLING UPPER LOW AND
ASSOCIATED VORT LOBE WILL BE LIFTING NE ACROSS THE CENTRAL
APPALACHIANS AND AWAY FROM OUR AREA. NEARLY ZONAL FLOW WILL BE OVER
THE SOUTHERN TIER OF STATES...WITH AN ELONGATED SHORTWAVE MOVING
INTO THE OF AND MID MS RIVER VALLEYS. BY TUESDAY NIGHT AN UPPER
RIDGE OVER THE WESTERN ATLANTIC BUILDS WEST OVER THE SOUTHEASTERN
STATES. THIS RESULTS IN OHIO VALLEY SHORTWAVE ENERGY BEING CHANNELED
EASTWARD TOWARD CHESAPEAKE BAY THROUGH WEDNESDAY...AND REMAINING
NORTH OF OUR AREA.

AT THE SURFACE...MOISTURE ASSOCIATED WITH THE UPPER LOW WILL BE OVER
THE MID ATLANTIC REGION MONDAY EVENING...WITH SLIGHTLY DRIER AIR
WORKING INTO OUR AREA IN WAKE OF THE UPPER LOW. THIS RELATIVE LULL
IN MOISTURE LAST THROUGH TUESDAY NIGHT...FOLLOWED BY A SUBSTANTIAL
MOISTURE INCREASE FROM THE NORTH ON WEDNESDAY...SOUTH OF WEAKENING
AND DECELERATING COLD FRONT IN THE OH RIVER VALLEY.

ALTHOUGH A RELATIVE DRYING TREND IS EXPECTED EARLY ON...ENOUGH
MOISTURE AND INSTABILITY WILL REMAIN FOR PRIMARILY DIURNALLY DRIVEN
CONVECTION ON MONDAY EVENING AND TUESDAY. WITH INCREASING MOISTURE IN
NC ON WEDNESDAY...PRECIPITATION COVERAGE SHOULD BE MORE WIDESPREAD
THERE...BUT INSTABILITY MAY BE MORE LIMITED DUE TO CLOUD COVER
LIMITING HEATING. TEMPERATURES WILL RUN NEAR NORMAL...EXCEPT ALONG
INTERSTATE 40 ON WEDNESDAY...WHERE CLOUD COVER WILL LIMIT DAYTIME
HEATING.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AT 230 PM EDT SUNDAY...ON THURSDAY AN UPPER RIDGE WILL EXTEND FROM
THE WESTERN ATLANTIC TO TX...WITH ZONAL FLOW TO THE NORTH FROM THE
ROCKIES TO ME. THE GFS STRENGTHENS THE RIDGE OVER THE EASTERN USA
INTO THE WEEKEND...WHILE THE ECMWF RETROGRADES IT TO THE SOUTHERN
ROCKIES...ALLOWING FORM SOME SHALLOW TROUGHING OVER THE EAST.

AT THE SURFACE...HIGH PRESSURE WILL BE CENTERED OVER THE SOUTHERN
APPALACHIANS ON THURSDAY...WITH LEE TROUGHING OVER THE PIEDMONT...
AND A STATIONARY FRONT FROM THE OH RIVER VALLEY TO THE DELMARVA
PENINSULA. THIS PATTERN PERSIST THROUGH NEXT SUNDAY. MOISTURE TO THE
SOUTH OF THE BOUNDARY WILL BE GREATER OVER NC THAN SC AND GA. THE
MODELS SHOWS MODEST INSTABILITY...BUT GENERALLY VERY LIGHT STEERING
FLOW...SUGGESTING HEAVY RAINFALL WHERE LIFT CAN BE GENERATED.
TEMPERATURES WILL TREND UPWARD TO ABOVE NORMAL AS HEIGHTS RISE ALOFT.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
AT KCLT...INSTABILITY CONTINUES TO STEADILY BUILD OVER THE PIEDMONT
THIS AFTERNOON AHEAD OF APPROACHING UPPER VORT LOBE ENERGY FROM THE
TROUGH W OF THE MTNS. THE HRRR HAS CONVECTION CROSSING THE AIRFIELD
CIRCA 19Z TO 20Z...BUT IT INITIALIZED POORLY IN UPSTREAM AREAS...SO
WILL CONFINE PRECIP MENTION TO SHRA AT PRESENT. SHOWERS WILL
DIMINISH THIS EVENING. THERE WILL BE A CHANCE OF LOW STRATUS AGAIN
MONDAY MORNING EVEN THOUGH THIS IS NOT DEPICTED ON THE MODELS/MOS.
EXPECT SW FLOW THROUGH THE PERIOD...MAINLY 10 TO 15 KT WITH A FEW
LOW END GUSTS THIS AFTN...THEN LIGHTER THE REST OF THE PERIOD.

ELSEWHERE...SHOWER COVERAGE WILL FILL IN ACROSS THE MTN AND FOOTHILL
SITES THROUGH THE LATE AFTERNOON HOURS AS THE BETTER UPPER VORT LOBE
SUPPORT ARRIVES. TSRA CHANCES WILL BE BEST FROM KAVL TO KHKY...BUT
CANNOT RULE OUT A VCTS AT THE UPSTATE SITES SINCE INSTABILITY HAS
SLOWLY REBOUNDED AFTER THE MORNING CLOUDS SCATTERED. ANTICIPATE SW
FLOW WITH LOW END GUSTS THIS AFTN...BECOMING LIGHT TONIGHT...AND
TURNING MORE NW AT KAVL BEHIND THE PASSING TROUGH. LOW CLOUDS WILL
CERTAINLY BE POSSIBLE AGAIN MON MORNING...BUT WITH THE BEST CHANCE
IN THE FRENCH BROAD VALLEY AT KAVL.

OUTLOOK...THE WEATHER REGIME WILL RETURN TO A MORE TYPICAL DIURNAL
SUMMERTIME PATTERN THROUGH THE WEEK. THIS WILL MEAN SCATTERED
AFTN/EVENING THUNDERSTORMS OVER THE AREA...MAINLY IN THE MTNS...WITH
ASSOCIATED RESTRICTIONS UNDER THE HEAVIEST SHOWERS...AND SPOTTY LOW
CLOUDS AND FOG THE FOLLOWING MORNING.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       MED   79%     HIGH  81%     MED   63%     MED   79%
KHKY       HIGH 100%     HIGH 100%     MED   72%     HIGH  86%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH  81%     HIGH  81%

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...FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR GAZ010-017.
NC...FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR NCZ048-051-
     052-058-059-062-063.
SC...NONE.

&&

$$
SYNOPSIS...HG
NEAR TERM...HG
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...HG


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