Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 270226
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1026 PM EDT WED AUG 26 2015

.SYNOPSIS...
CANADIAN HIGH PRESSURE WILL MAINTAIN MOSTLY DRY CONDITIONS THROUGH
FRIDAY. AS THE HIGH SLIDES OFFSHORE OVER THE WEEKEND...THE CHANCES
FOR SCATTERED TO WIDESPREAD SHOWERS AND THUNDERSTORMS WILL INCREASE
OVER THE WEEKEND AND WELL INTO NEXT WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
0230 UTC UPDATE...SKY COVER WAS UPDATED PER INFRARED SATELLITE
IMAGERY....WITH MOST CLOUD COVER OVER THE MOUNTAINS...AND VERY
LITTLE OVER THE FOOTHILLS AND PIEDMONT. TEMPERATURES WERE ADJUSTED
DOWN SLIGHTLY FOR A BETTER FIT WITH NEIGHBORING OFFICES. DEW POINTS
WERE UPDATED FROM THE LATEST ADJMAV.

2315 UTC UPDATE...SKY COVER WAS UPDATED FROM VISIBLE SATELLITE
IMAGERY...AND WINDS WERE UPDATED WITH THE LATEST NAM GUIDANCE.

2020 UTC UPDATE...SKY COVER HAS BEEN UPDATED FROM THE LATEST VISIBLE
SATELLITE IMAGERY...RESULTING IN A DECREASE OVER THE FOOTHILLS AS
WELL AS THE NC PIEDMONT.

AS OF 230 PM EDT WEDNESDAY...CONTINUED QUIET THROUGH THE NEAR TERM.
EASTERLY TO NORTHEASTERLY SURFACE FLOW CONTINUES AROUND A SURFACE
LOW ALONG THE SC/GA COAST...LEADING TO WEAK UPSLOPE COMPONENT AT THE
HIGHER ELEVATIONS AND A WEAK BUT PERSISTENT LOW-LEVEL INVERSION...
ABOUT 700MB...ALLOWING FOR SOME MOISTURE POOLING AND MORE CLOUDS
THAN WE MIGHT OTHERWISE HAVE IN THE DRY REGIME ALOFT. UPPER TROUGH
CONTINUES IN PLACE OVER THE EASTERN PORTION OF THE COUNTRY AND AS
THE PARENT LOW BEGINS TO LIFT NORTH...A PIECE OF THE TROUGH WILL CUT
OFF OVER THE SOUTHEAST AND SHIFT EVER SO SLIGHTLY WEST...TAKING THE
GA/SC COASTAL SURFACE LOW FARTHER INLAND TOWARD THE GULF COAST.

DEWPOINTS WILL BE ON THE INCREASE THIS AFTERNOON AS WINDS BEGIN TO
SLOWLY SHIFT EASTERLY /VS NORTHEASTERLY/ IN RESPONSE TO THE SLOW
MOVEMENT OF THE SURFACE LOW. WINDS SHOULD DIE DOWN TONIGHT AND TEMPS
WILL AGAIN DROP BELOW SEASONAL NORMALS...WITH THE POSSIBILITY OF
SOME LIGHT FOG IN THE TYPICAL LOCATIONS. NEW GUIDANCE HAS COME IN A
BIT COOLER FOR HIGHS ON THURSDAY...CONTINUING THE BELOW-NORMAL
TREND. AS THE AFOREMENTIONED PIECE OF ENERGY ALOFT BREAKS OFF
TOMORROW...925-850MB FLOW WILL PICK UP OUT OF THE SOUTHEAST...
INCREASING THE UPSLOPE COMPONENT AND BRINGING ADDITIONAL MOISTURE
AND INSTABILITY INTO THE AREA. HAVE KEPT SLIGHT CHANCE POPS ALREADY
ADVERTISED OVER THE MOUNTAINS...BUT INCREASED CLOUD COVER.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 230 PM WEDNESDAY...WE EXPECT A TRANSITION FOR THE END OF THE
WEEK TO SOMETHING MORE SUPPORTIVE OF DIURNALLY ENHANCED DEEP
CONVECTION. FRIDAY STILL LOOKS LIKE A RELATIVELY QUIET DAY WITH
MAINLY JUST SOME RIDGETOP CONVECTION IN THE AFTERNOON. TEMPS WILL BE
BACK TO NORMAL. FROM THAT POINT ON...CONFIDENCE IS NOT GREAT AS THE
MODELS DIFFER IN THE HANDLING OF A WEAK CLOSED LOW THAT IS ORPHANED
OVER THE DEEP SOUTH BY FRIDAY. THE GFS HAS BEEN CONSISTENTLY
STRONGER AND MORE DYNAMIC WITH LIFTING THIS FEATURE NWD OVER THE
WEEKEND AS IT GETS PICKED UP BY A SHORT WAVE MOVING ACROSS THE
PLAINS...WHILE THE OTHER MODELS HAD BEEN MORE MUTED. THE 12Z NAM HAS
TRENDED TOWARD THE GFS IN THAT IT HAS A BETTER DEFINED VORT CENTER
MOVING ACROSS THE SRN APPLACHIANS ON SATURDAY AFTERNOON...ALTHO THE
GFS APPEARS TO BE DELAYED UNTIL SUNDAY WITH ITS PRIMARY VORT CENTER.
ALTHO CONFIDENCE IS GROWING THAT CONVECTIVE PRECIP WILL OCCUR ON
SATURDAY AFTERNOON...THE DIFFERENCE IN TIMING SUGGESTS KEEPING
PRECIP PROBABILITY DOWN IN THE CHANCE RANGE ON SATURDAY...UNTIL
BETTER AGREEMENT IS SEEN...AT WHICH TIME WE MAY END UP WITH A LIKELY
POP.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 2 PM ON WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH UPPER RIDGING TO OUR WEST AND AN IMPRESSIVE LOOKING
EMBEDDED UPPER SHORTWAVE MOVING ACROSS THE SOUTHERN GREAT LAKES.
SIMULTANEOUSLY...THE UPPER LOW ASSOCIATED WITH WHAT IS NOW TS ERIKA
SHOULD BE SOMEWHERE OVER THE SOUTHERN BAHAMAS. AS WE MOVE THRU SUN
AND INTO MON...THE SHORTWAVE GRADUALLY DRIFTS EASTWARD BUT REMAINS
TO OUR NORTH WHILE TS ERIKA MOVES OVER SOUTHERN FLORIDA. OVER THE
REMAINDER OF THE PERIOD...BROAD UPPER RIDGING SPREADS BACK OVER THE
REGION WHILE THE SHORTWAVE EVENTUALLY MOVES OFF THE ATLANTIC COAST
AND THE REMNANTS OF ERIKA REMAIN OVER/NEAR THE SE COAST. AT THE
SFC...THE SUBTROPICAL BERMUDA HIGH IS EXPECTED TO REMAIN IN CONTROL
OF THE LARGE SCALE PICTURE FOR MOST OF THE PERIOD WITH MOIST SLY
FLOW PERSISTING INTO EARLY NEXT WEEK. THE MAIN QUESTION FOR THE
PERIOD DEALS WITH EXACTLY WHERE TS ERIKA WILL END UP BY DAYS 6 AND
7. BOTH THE GFS AND ECWMF HAVE THE TROPICAL SYSTEM MOVING UP THE
FLORIDA PENINSULA EARLY NEXT WEEK...HOWEVER THE ECMWF STALLS THE LOW
OUT JUST TO OUR SOUTH BY THE MIDDLE OF THE WEEK WHILE THE GFS MOVES
RIGHT OVER THE CAROLINAS BY DAY 7. IT IS TOO EARLY TO PUT MUCH
CONFIDENCE IN EITHER SCENARIO...BUT IF A GFS TYPE SOLUTION DOES PAN
OUT...WE COULD HAVE WIDESPREAD FLOODING OVER THE CWFA LATER NEXT
WEEK. AS FOR THE SENSIBLE FCST...NO SIGNIFICANT CHANGES WERE MADE
WITH CHANCE POPS EACH DAY AND TEMPS ABOUT 2 TO 4 DEGREES ABOVE
CLIMATOLOGY.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
AT KCLT...VFR...WITH LIGHT WINDS VEERING FROM NNE TO ENE. ONLY MODEST
CLOUD COVER IS EXPECTED...WITH MORE LOW CLOUD THAN HIGH CLOUD BY THE
END OF THE FORECAST.

ELSEWHERE...SOME GUIDANCE HINTS AT DAYBREAK MVFR FOG IN THE NC
MOUNTAIN VALLEYS...INCLUDING KAVL. OTHERWISE...VFR...WITH A LOW VFR
CIGS AT KAVL OVERNIGHT. WINDS WILL FAVOR THE N AT KAVL
OVERNIGHT...VEERING SW ON THURSDAY. FOOTHILLS WINDS WILL VEER FROM
NNE TO ENE ON THURSDAY.

OUTLOOK...MOISTURE WILL SLOWLY INCREASE FROM THE SOUTH AND EAST LATE
IN THE WEEK. ISOLATED TO SCATTERED AFTERNOON AND EVENING
SHRA/TSRA ARE EXPECTED TO RETURN THIS WEEKEND.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       HIGH 100%     HIGH  98%     HIGH  95%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     MED   79%     HIGH  98%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     MED   68%
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...JPT
NEAR TERM...JAT/TDP
SHORT TERM...PM
LONG TERM...JPT
AVIATION...JAT



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