Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 062058
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
458 PM EDT MON JUL 6 2015

.SYNOPSIS...
A BROAD UPPER RIDGE WILL STRENGTHEN AND MIGRATE OVER THE SOUTHEAST
INTO THE WEEKEND. SHOWER AND THUNDERSTORM CHANCES WILL FAVOR THE
AFTERNOON AND EVENING. TEMPERATURES WILL INCREASE ABOVE NORMAL
LEVELS.

&&

.NEAR TERM /THROUGH TUESDAY/...
AS OF 5 PM...TEMPS WERE RUNNING ABOUT A CATEGORY WARMER THAN THE
TREND IN THE FCST...SO THAT WILL BE IMPROVED. OTHERWISE...WIDELY
SCATTERED SHOWERS AND THUNDERSTORMS HAD FORMED ACROSS THE REGION AND
THAT SHOULD CONTINUE THROUGH AT LEAST SUNSET.

PREVIOUS DISCUSSION...

AT 230 PM MONDAY...FOR THE REMAINDER OF THE AFTERNOON...EXPECT SCT
CONVECTION TO INCREASE ACROSS THE SOUTHERN UPSTATE BY MID AFTERNOON
ALONG THE AXIS OF BEST INSTABILITY IN THE VICINITY OF THE LEE
TROUGH. LATEST HRRR DEVELOPS SCT SHRA/TSRA NORTHWARD BY LATE
AFTERNOON INTO THE EASTERN UPSTATE AND THE NC PIEDMONT. SO WILL ALSO
HAVE SOMOE SCT POPS THERE. CAN`T RULE OUT A FEW STRONG TO SEVERE
STORMS AS CAPES HAVE INCREASED TO AROND 2000J AND SOME DRY AIR NOTED
IN MID LEVELS. ACTIVITY SHOULD WANE WITH LOSS OF HEATING THIS
EVENING.

IN REGARD TO THE PICTURE...THE REMNANTS OF THE UPPER TROUGH WAS
GRADUALLY LIFTING TO THE NE ALONG WITH A LOBE OF VORTICITY NOTED IN
THE IR IMAGERY. THIS WEAK FORCING SHOULD MOVE NE OF THE WESTERN
CAROLINAS EARLY TONIGHT. IN ITS WAKE...A WEAK AREA OF SURFACE HIGH
PRESSURE WILL BUILD OVER THE AREA TONIGHT. HENCE FOR THE
OVERNIGHT...IT SHOULD BECOME MOSTLY CLEAR WITH SOME FOG DEVELOPING
IN THE MOUNTAIN VALLEYS. MINIMUM TEMPS WILL BE MILD WITH LOWS IN THE
UPPER 60S TO AROUND 70 OUTSIDE THE MOUNTAINS...WITH UPPER 50S TO MID
60S MOUNTAINS.

TUESDAY IS SHAPING UP TO BE A TYPICAL JULY DAY WITH PLENTY OF
SUNSHINE AND VERY WARM TEMPERATURES. DIFFERENTIAL HEATING AND WEAK
UPSLOPE FLOW IN THE MOUNTAINS WILL TRIGGER SCT AFTERNOON
THUNDERSTORMS THERE. IT LOOKS LIKE THE REMAINDER OF THE AREA SHOULD
REMAIN DRY EXCEPT PERHAPS FOR THE FOOTHILLS WHERE SOME MOUNTAIN
STORMS MAY DRIFT IN LATE IN THE DAY. MAX TEMPS WILL BE A COUPLE
DEGREES ABOVE CLIMO.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
OF 230 PM EDT MONDAY... THE SHORT TERM PART OF THE FORECAST STILL
CONTINUES A THEME FOR THE RETROGRESSION OF THE BERMUDA HIGH INTO OUR
FORECAST AREA (FA) TUESDAY NIGHT AND WEDNESDAY...ALBEIT NOT YET
FIRMLY ENTRENCHED. THE UPPER AIR PATTERN THEN TAKES ON A W-SWLY LOOK
AT THAT TIME...WITH PACKETS OF ENERGY MOVING THROUGH THE FLOW...
ESPECIALLY ON OUR NORTHERN AND WESTERN PERIPHERY.

CONVECTION TUESDAY NIGHT IN THE MOUNTAINS SHOULD WANE WITH LOSS OF
HEATING...ALTHOUGH ALONG THE TENNESSEE/NORTH CAROLINA STATE LINE A
FEW CELLS MAY TRY TO HOLD ON A LITTLE LONGER WITH WEAK FORCING
ALOFT.

MEANWHILE ON WEDNESDAY...THERE APPEARS TO BE ENOUGH INSTABILITY...
AND HEIGHTS HAVE NOT REACHED THEIR APEX YET...PLUS TAIL OF ENERGY
PACKETS (DPVA) MOVING THROUGH THE MEAN FLOW...FOR A CHANCE POP
FORECAST IN THE MOUNTAIN AND SLIGHT CHANCE ELSEWHERE. WE JUST NEED
TO KEEP AN EYE ON ANY CONVECTION NORTH OF OUR REGION...IN A WAFFLING
FRONTAL PATTERN...TRYING TO TURN SEWD TOWARD OUR NORTHERN FA. THE
NAM SUBTLY IMPLIES SOMETHING LIKE THIS HEADING OFF TO OUR EAST...
THEREFORE A NOTE OF CAUTION.

ONCE AGAIN CONVECTION WILL WANE WEDNESDAY NIGHT. IT APPEARS RIDGING
ALOFT WILL BE BUILDING IN FULL FORCE THURSDAY. WE HAVE KEPT THE POPS
ON THE VERY LOW SIDE...BASICALLY TRYING TO EMPHASIS THE HIGHER
TERRAIN LOCATIONS. WE WERE A LITTLE CONCERNED WITH THE LEE SIDE
TROFFING PROVIDING A WEAK FOCUS AROUND THE REGION...THUS POPS JUST
INTO THE SLIGHT CATEGORY...WHICH FITS WELL WITH OUR NEIGHBORS.

WE HAVE FOLLOWED THE TEMPERATURE PROFILE OF THE MODELS WHICH BRING
TEMPERATURES UP DURING THIS PART OF THE CYCLE...AS RIDGING AND HEAT
BEGIN ANOTHER SURGE.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AT 200 PM EDT MONDAY...ON FRIDAY AN UPPER RIDGE WILL EXTEND FROM THE
GULF STATES TO THE GREAT LAKES. THE RIDGE AMPLIFIES ALMOST TO HUDSON
BAY ON SATURDAY...THEN RETROGRESSES TO THE SOUTHERN PLAINS BY
SUNDAY...AND TO THE SOUTHERN ROCKIES BY MONDAY.

AT THE SURFACE...HIGH PRESSURE WILL BE CENTERED OVER THE SOUTHERN
APPALACHIANS ON FRIDAY...WITH A LEE TROUGH OVER THE PIEDMONT...WHILE
A STATIONARY FRONT RESIDES OVER THE OH RIVER VALLEY. ON SATURDAY THE
WESTERN PORTION OF THE FRONT DIPS SOUTH INTO NC...BUT BY SUNDAY IT
IS EXPECTED TO RETURN NORTH AS A WARM FRONT. MONDAY FEATURES A AN
IMPROVED PRESSURE GRADIENT AND RESULTING WESTERLY FLOW...AS THE
RETROGRESSING UPPER RIDGE ALLOWS FOR EAST COAST TROUGHING AND A DIP
OF THE WESTERLIES TO OUR LATITUDE.

INSTABILITY IS EXPECTED TO BE LIMITED EARLY ON UNDER THE UPPER
RIDGE...ALTHOUGH NO CAPPING INVERSION IS DEPICTED IN MODEL
SOUNDINGS. AS THE UPPER RIDGE SLIDES WEST...MORE ROBUST INSTABILITY
APPEARS BY THE WEEKEND. STEERING FLOW WILL BE QUITE LIGHT UNDER THE
RIDGE...BUT IMPROVES AS THE RIDGE DEPARTS AND WINDS PICK UP WITH
EAST COAST TROUGHING. TEMPERATURES WILL RUN ABOVE NORMAL...WITH A
SLIGHT DECLINE LATE IN THE FORECAST AS HEIGHTS FALL ALOFT WITH THE
DEPARTURE OF THE RIDGE.

&&

.AVIATION /21Z MONDAY THROUGH SATURDAY/...
AT KCLT...MAIN CONCERN IS WHETHER ANY CONVECTION WILL AFFECT THE
AIRFIELD THIS AFTERNOON AND/OR EARLY EVENING. BEST INSTABILITY AXIS
IS TO THE S-SW AND THAT IS WHERE SOME RADAR ECHOES ARE CURRENTLY
NOTED OVER THE SW UPSTATE OF SC. LATEST HRRR DEVELOPS SCT TSRA
EASTWARD ALONG THAT INSTABILITY AXIS BY 20Z AND THEN TO THE NORTH
CIRCA 21-22Z. CONFIDENCE STILL NOT HIGH ENUF TO GO WITH A TEMP
TSRA...SO WILL STAY THE COURSE WITH A VCSH. NO RESTRICTIONS EXPECTED
EXCEPT IF A TSRA AFFECTS THE AIRFIELD.

ELSEWHERE...SAME CONCERNS AS TO WHETHER ANY CONVECTION WILL AFFECT
THE AIRFIELDS. LOOKS LIKE THE SC AIRFIELDS WILL HAVE THE BEST CHANCE
AS THEY ARE CLOSER TO THE INSTABILITY MAXIMUM OVER THE SOUTHERN
UPSTATE AND THE LEE TROUGH. HENCE...WILL CARRY A VCTS AT KAND/KGSP
AND KGMU FROM ABOUT 20-23Z. THUNDER CHANCES LESS AT KAVL AND KHKY SO
WILL JUST CARRY A VCSH THERE. THE ONLY OTHER RESTRICTION IS FOR SOME
FOG AT AVL EARLY TUE MORNING. CURRENTLY FORECASTING VSBY`S TO LOWER
TO AROUND 2 MILES IN FOG JUST BEFOR SUNRISE.

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...

            21-03Z        03-09Z        09-15Z        15-18Z
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 100%
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_TABLES

&&

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

&&

$$
SYNOPSIS...LG/PM
NEAR TERM...LG
SHORT TERM...TS
LONG TERM...JAT
AVIATION...LG


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