Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 022031
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
431 PM EDT SUN AUG 2 2015

.SYNOPSIS...
DRY HIGH PRESSURE WILL REMAIN IN PLACE ACROSS THE AREA THROUGH
MONDAY. LOW LEVEL MOISTURE WILL GRADUALLY RETURN THROUGH THE WORK
WEEK AS ANOTHER COLD FRONT APPROACHES FROM THE NORTHWEST THEN MOVES
INTO THE AREA AND STALLS.

&&

.NEAR TERM /THROUGH MONDAY/...
400 PM UPDATE...STILL NO SIGN YET OF DEVELOPING SHRA OVER THE MTNS
PER RADAR...BUT LATEST GOES IMAGERY HAS NOT INDICATED CU HAVE
PEAKED. MESO MODELS ARE GENERALLY DRY THRU THE AFTN...BUT I DO NOT
FEEL CONFIDENT ENOUGH TO REMOVE THE LOW POPS THERE. TOUCHING UP
SKY/T/TD WITH THIS UPDATE...BUT OTHERWISE EVERYTHING LOOKS GOOD.

AS OF 230 PM EDT SUNDAY...VERY DRY SURFACE LAYER REMAINS IN PLACE
ACROSS THE AREA TODAY...BUT ENOUGH OF A MID-LEVEL LAPSE RATE IN THE
MOUNTAINS TO ALLOW ISOLATED CONVECTION TO DEVELOP THIS AFTERNOON.
HRRR AND OTHER HI-RES GUIDANCE CONTINUE TO INDICATE THIS...AND
CONVECTION LOOKS TO BE BUBBLING ALREADY PER SATELLITE. ALSO SEEING
SOME CONVECTION TO THE SOUTH A LITTLE CLOSER TO THE BETTER SURFACE
MOISTURE ASSOCIATED WITH THE STALLED FRONT.

SYNOPTIC PATTERN REMAINS RELATIVELY UNCHANGED WITH LONGWAVE TROUGH
DOMINATING THE EASTERN SEABOARD. SHORTWAVE SHOULD PUSH THROUGH THE
AREA TONIGHT INTO EARLY TOMORROW...BUT SOME DISCREPANCIES ON HOW
STRONG THE SHORTWAVE IS. NAM IS THE STRONGEST WITH MORE SIGNIFICANT
VORTLOBE PUSHING INTO NORTH CAROLINA. THIS RESULTS IN MORE
CONVECTIVE ACTIVITY THAN OTHER GUIDANCE...AND QUITE A BIT MORE
SURFACE MOISTURE AND OVERNIGHT FOG POTENTIAL. NAM IS A BIT OF AN
OUTLIER WITH THIS...SO LEANED MORE TOWARD THE GFS/ECMWF.

OTHER ITEM OF NOTE IS SURFACE WAVE/LOW NEAR THE FLORIDA BIG BEND
THIS AFTERNOON. THIS LOW WILL RIDE NORTHEAST ALONG THE STALLED
BOUNDARY OVERNIGHT AND GENERALLY ALONG THE SOUTH CAROLINA COAST BY
MONDAY AFTERNOON. GUIDANCE IN FAIRLY DECENT AGREEMENT THOUGH THE GFS
IS DEFINITELY ON THE STRONGER SIDE WITH THIS LOW. FOR NOW...LOOKS
LIKE ANY SENSIBLE WEATHER IMPACTS WILL REMAIN OUT OF OUR FORECAST
AREA AND CLOSER TO THE COAST...BUT WILL CONTINUE TO MONITOR. FOR NOW
THE LOW LOOKS UNLIKELY TO DEVELOP TROPICAL CHARACTERISTICS...REFER
TO NHC TROPICAL WEATHER OUTLOOK.

TEMPS WILL REMAIN NEAR TO JUST ABOVE NORMAL VALUES THROUGH THE NEAR
TERM BUT WITH A TREND UPWARDS AS SURFACE WINDS SWING AROUND TO THE
SOUTH ALLOWING RETURN MOIST FLOW TO BEGIN SETTING UP TOWARD THE END
OF THE PERIOD. HOWEVER...AS THE SURFACE LOW TRACKS TO THE
SOUTHEAST...WILL LIKELY SEE A BRIEF PERIOD OF NORTHWEST SURFACE FLOW
BEFORE THE WINDS RESPOND AGAIN TO THE LARGER SYNOPTIC PATTERN AS WE
TRANSITION INTO THE SHORT TERM.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM SUNDAY...THE MIDDLE PART OF THE WEEK LOOKS LIKE A
GRADUAL RETURN TO MORE TYPICAL SUMMERTIME HUMIDITY...AND MORE
TYPICAL DIURNAL THUNDERSTORM CHANCES. THE MODELS STILL SHOW THE
EASTERN UPPER TROF GRADUALLY LOSING AMPLITUDE THRU WEDNESDAY AS A
SHORT WAVE COMES OUT OVER THE PLAINS AND MIDWEST. THE APPROACH OF
THIS FEATURE ALLOWS SOME WEAK MOISTURE TRANSPORT BACK INTO THE AREA
THAT SHOULD IMPROVE OUR POTENTIAL FOR INSTABILITY WITH SOME
AFTERNOON HEATING...WHICH SHOULD BE SUBSTANTIAL...AT LEAST ON
TUESDAY WHICH LOOKS LIKE THE HOTTEST DAY. WHAT REMAINS TO BE SEEN IS
HOW THE DETAILS WORK OUT. THE MODELS HAVE A SHORT WAVE MOVING PAST
TO THE NORTH LATE MONDAY THAT LEAVES A SURFACE BOUNDARY STRETCHED
OUT TO THE NORTH ON TUESDAY...WHICH SHOULD PROVIDE SOME FOCUS FOR
SHOWERS AND STORMS. THE GFS SEEMS UNDERDONE WITH ITS LACK OF PRECIP.
THE NAM MIGHT BE WRONG ON SOME OF THE DETAILS BUT THINK IT IS RIGHT
WITH DEVELOPING SOME AFTERNOON STORMS SOUTH OF THE BOUNDARY. FOR
THAT REASON...HAVE KEPT AT LEAST A SLIGHT CHC ACROSS THE NC PART OF
THE FCST AREA INTO THE EARLY EVE. WEDNESDAY SHOULD BE MORE FAVORABLE
WITH SLIGHTLY BETTER MOISTURE AS THE WAVE APPROACHES FROM THE
WEST... BUT ONCE AGAIN THE GFS IS UNIMPRESSED. THINK THE PATTERN
FAVORS POTENTIAL A BIT ABOVE CLIMATOLOGY...SO WILL SHADE ON THE HIGH
SIDE OF GUIDANCE WITH A CHANCE ACROSS JUST ABOUT THE WHOLE FCST AREA
IN THE AFTERNOON. A BIT MORE CONVECTION SHOULD MEAN A BIT LOWER HIGH
TEMPS.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 210 PM SUNDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
THURSDAY WITH BROAD UPPER TROFFING CENTERED OVER NEW ENGLAND
AND PERSISTENT UPPER RIDGING OVER THE WESTERN CONUS. OVER THE NEXT
COUPLE OF DAYS...THE UPPER TROF LIFTS TO THE NE AND ANOTHER NORTHERN
STREAM UPPER TROF HELPS TO FLATTEN THE RIDGE OVER THE WEST. SIMULTANEOUSLY
A SERIES OF EMBEDDED UPPER SHORTWAVES APPROACH THE FCST AREA FROM THE
NORTHWEST ON BOTH THURS AND FRI. TOWARDS THE END OF THE PERIOD NEXT
SUN...THE UPPER RIDGE TRIES TO BUILD EASTWARD AND HEIGHTS COULD BEGIN
TO RISE AGAIN OVER THE SOUTHEAST. AT THE SFC...THE SUBTROPICAL
BERMUDA HIGH WILL MAINTAIN ITS INFLUENCE OVER THE SE REGION THRU
MOST OF THE PERIOD WITH GENERALLY LIGHT SLY FLOW. THE LONG RANGE
MODELS REMAIN IN POOR AGREEMENT WRT THE SFC PATTERN EVOLUTION FOR
MOST OF THE MEDIUM RANGE. THEY ATTEMPT TO SPIN UP MULTIPLE LOWS
OVER THE SE REGION AND THEN MOVE THEM OFFSHORE ON FRI AND SAT YET
THE PLACEMENT AND TIMING STILL DIFFER QUITE A BIT...ALTHOUGH THE ECMWF
AND CANADIAN MODELS HAVE COME INTO BETTER AGREEMENT WITH EACH OTHER.
AS SUCH...I LEANED MORE TOWARDS AN ECMWF/CMC TYPE SOLUTION. I KEPT
POPS AT A HIGH END SOLID CHANCE FOR MOST OF THURS AND FRI AND TAPER THEM
BACK FOR THE WEEKEND. THE LATER INTO THE WEEKEND WE MOVE...THE DRIER IT IS
LIKELY TO BE. TEMPS START OUT NEAR NORMAL AND THEN COOL A FEW DEGREES
THRU THE PERIOD.

&&

.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
AT KCLT...VFR THROUGH THE PERIOD. LIGHT ENE WINDS WILL CONTINUE
THROUGH THE REMAINDER OF THE AFTERNOON...GRADUALLY SHIFTING ESE AND
SE THIS EVENING /CURRENT TIMING OF WIND SHIFT TO S SIDE IS 00Z/.
ANOTHER ROUND OF FEW-SCT CU ON MONDAY...WITH LOWER BASES GENERALLY 4-
5KFT.

ELSEWHERE...MAINLY VFR. CONTINUED SCT CU AROUND 6-7KFT THIS
AFTERNOON AND CANNOT RULE OUT ISOLATED CONVECTION ESPECIALLY CLOSER
TO KAVL...BUT TOO ISOLATED IN NATURE TO MENTION AT TAF SITES. LIGHT
WINDS VEERING GRADUALLY FROM ENE TO SE THROUGH THE PERIOD...EXCEPT
AT KAVL WHERE THEY WILL VEER MORE GREATLY AROUND FROM SE TODAY TO NW
TONIGHT. GUIDANCE IS IN DECENT AGREEMENT ON FOG POTENTIAL THOUGH NOT
CONSISTENT ON ACTUAL VSBY VALUES. HAVE INTRODUCED MVFR FOG AT KAND
AND KAVL AROUND DAYBREAK. NAM WANTS TO GO ALL OUT WITH LOW CIGS AS
WELL BUT HAVE DISCOUNTED THAT SOLUTION. IMPROVEMENT MONDAY MORNING
WITH ANOTHER ROUND OF FEW-SCT CU IN THE AFTERNOON.

OUTLOOK...GRADUALLY INCREASING PRECIPITATION/RESTRICTION CHANCES
THROUGH MID WEEK AS MOIST SOUTHERLY FLOW RETURNS AHEAD OF THE NEXT
COLD FRONT.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  97%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  95%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH  95%     HIGH  95%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  95%

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...JPT
NEAR TERM...TDP/WIMBERLEY
SHORT TERM...PM
LONG TERM...JPT
AVIATION...TDP/WIMBERLEY


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