Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 281047
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
647 AM EDT THU AUG 28 2014

.SYNOPSIS...
A COLD FRONT WILL DROP DOWN INTO NORTH CAROLINA FROM THE NORTH
TODAY...LINGERING OVER THE REGION BRIEFLY BEFORE MOVING BACK
NORTH ON FRIDAY. A BERMUDA HIGH WILL SET UP FOR THE WEEKEND AND
EARLY NEXT WEEK...BRINGING TYPICAL SUMMERTIME HEAT AND HUMIDITY...
WITH SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS EACH DAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM...I WILL ISSUE A QUICK UPDATE TO REDUCE THE MENTION OF
FOG ACROSS THE REGION. THE PATCHY DENSE FOG WILL BE LIMITED TO THE
EXTREME WESTERN NC MTN VALLEYS. OTHERWISE...THE CURRENT FORECAST
APPEARS IN GOOD SHAPE.

AS OF 330 AM...BROAD SFC HIGH PRESSURE WILL REMAIN ACROSS MOST OF
THE SOUTHEAST TODAY...RESULTING IN LIGHT NW TO CALM WINDS THIS
MORNING. A WEAK BACK DOOR COLD FRONT IS EXPECTED TO REACH THE I-40
CORRIDOR BY MID DAY...THEN BECOME STATIONARY. FORECAST SOUNDINGS
INDICATES THAT MOISTURE WILL POOL ALONG AND AHEAD OF THE COLD
FRONT...WITH PW VALUES INCREASING TO AROUND 1.4 INCHES. PLAIN VIEW
OF THE NAM SHOWS A BAND OF 1500-2000 J/KG OF CAPE NEAR THE SFC
BOUNDARY. AT H5...HEIGHTS REMAIN AROUND 590 DM...SOURCED FROM A
RIDGE CENTERED OVER THE FL/GA LINE. THE LACK OF MID LEVEL SUPPORT
SHOULD LIMIT CONVECTION TO AREAS ALONG AND AHEAD OF THE COLD
FRONT...DURING THE PRIME DIURNAL HOURS. I WILL FORECAST CHC POPS
ACROSS THE RIDGES...WITH A BAND OF SCHC WEST TO EAST ACROSS THE I-40
CORRIDOR. NAM INDICATES THAT DCAPES MAY RANGE FROM 500-1000 J/KG
DURING THE HEAT OF THE AFTERNOON ACROSS THE NC ZONES. SPC DY1
OUTLOOK HIGHLIGHTS THE NC ZONES WITH A FIVE PERCENT CHC FOR DAMAGING
CONVECTIVE WINDS. THE HWO WILL HIGHLIGHT THE POTENTIAL FOR DAMAGING
MICROBURSTS AND LIGHTING THIS AFTERNOON AND EVENING. GFS INDICATES
THAT H85 TEMPS WILL REMAIN NEAR 20C THIS AFTERNOON. MILD LLVL
TEMPERATURES AND GOOD INSOLATION SHOULD PUSH HIGHS A LITTLE WARMER
THAN WED. I WILL FORECAST U80S WITHIN THE MTN VALLEYS TO GENERALLY
LOW 90S EAST OF THE MTNS.

NEAR TERM MODELS SHOW MID AND LLVL RIDGING INCREASING GRADUALLY
ACROSS THE REGION TONIGHT. THE STATIONARY FRONT IS EXPECTED TO
REMAIN ACROSS THE NORTHERN TIER OF THE FORECAST AREA...POSSIBLY
DRIFTING NORTH AS A WARM FRONT. I WILL MAINTAIN SCHC POPS ACROSS THE NRN
NC MTNS/FOOTHILLS/PIEDMONT THROUGH LATE TONIGHT. LOW TEMPERATURES
ARE FORECAST TO RANGE FROM THE L60 WITHIN THE MTN VALLEYS TO U60S
EAST OF THE MTNS.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
AS OF 300 AM THURSDAY...THE WEEKEND LOOKS LIKE A RETURN TO
MID-SUMMER WEATHER CONDITIONS. AN UPPER RIDGE IS STILL EXPECTED TO
BUILD ALONG THE EAST COAST ON FRIDAY...WHICH SHOULD MOVE WHAT IS
LEFT OF A WEAK BOUNDARY NORTHWARD AND AWAY FROM THE CAROLINAS. AS
THIS HAPPENS...THE UPPER RIDGE WILL ALLOW A BERMUDA HIGH TO GAIN
CONTROL ACROSS THE SOUTHEAST FOR SATURDAY AND SUNDAY. STUCK CLOSE TO
THE EARLIER PLAN FOR FRIDAY WITH A SLIGHT CHANCE FOR STORM
DEVELOPMENT ALONG THE MOUNTAIN RIDGES IN THE AFTERNOON...WITH A
BETTER CHANCE OVER THE NRN MOUNTAINS CLOSER TO THE FRONTAL REMNANTS
IN THE AFTERNOON. STILL THINK THE I-40 CORRIDOR COULD SEE A FEW
STORMS IN THE AFTERNOON IF THE NAM IS CORRECT WITH SOME EASTERLY
FLOW. THE MOISTURE WILL RETURN FROM THE GULF ON SATURDAY...BRINGING
SCATTERED THUNDERSTORMS BACK TO THE SAVANNAH RIVER BASIN AND NC
MOUNTAINS FIRST...THEN SPREADING UP FROM THE SW ACROSS THE REST OF
THE AREA THROUGH THE EVENING. AFTER SOME DIURNAL WEAKENING SATURDAY
NIGHT...STORM CHANCES LOOK BEST ON SUNDAY. THE GFS IS NOT QUITE AS
SUPPORTIVE AS IT WAS IN PREVIOUS RUNS...BUT STILL SHOWS SOME UPPER
DIVERGENCE MOVING OVERHEAD DURING PEAK HEATING AS A JET STREAK
PASSES TO THE NW. THE GFS AND ECMWF RESPOND NICELY TO THE INCREASE
IN MOISTURE AND WEAK FORCING...SO THINK THE POP CAN BE BUMPED UP A
BIT MORE FOR THE AFTERNOON. TEMPS WILL BE AT OR ABOVE NORMAL THROUGH
THE PERIOD.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
AS OF 315 AM THURSDAY...THE LATEST GUIDANCE IS IN FAIRLY GOOD
AGREEMENT WITH SLOWLY FLATTENING THE UPPER RIDGE ACROSS THE
SOUTHEAST EARLY NEXT WEEK AND THEN EXPANDING AT ACROSS THE SRN TIER
OF THE U.S. THROUGH THE MIDDLE PART OF THE WEEK. THAT WILL KEEP THE
MAINLY DIURNAL SHOWERS AND STORMS IN THE FORECAST AS WE RETAIN
ACCESS TO GULF MOISTURE COURTESY OF THE ELONGATED BERMUDA HIGH. THE
MAIN QUESTION BY MID-WEEK IS WHETHER OR NOT A SURFACE FRONT WILL
MAKE IT INTO THE REGION FROM THE N/NW ON WEDNESDAY. THERE DOES NOT
SEEM TO BE MUCH OF A PUSH ALOFT ON WEDNESDAY SO IT SEEMS DOUBTFUL
THE BOUNDARY WILL MAKE IT MUCH FARTHER S THAN THE FCST AREA. PRECIP
CHANCES SHOULD BE A BIT HIGHER WITH THE BOUNDARY IN THE AREA...WITH
LESS OF A DIURNAL TENDENCY. NO CHANGES WERE MADE TO TEMPS.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AT KCLT AND TERMINALS EAST OF THE MTNS...VFR CONDITIONS ARE FORECAST
TO PERSIST THROUGH THE 12Z TAF PERIOD. HOWEVER...KAND MAY CONTINUE
TO SEE PERIODS OF LAKE SOURCED VLIFR STRATUS DRIFT OVER THE TERMINAL
THROUGH 14Z. A WEAK BACK DOOR COLD FRONT IS EXPECTED TO REACH THE
VA/NC LINE BETWEEN 12Z-14Z...REMAINING ALONG THE I-40 CORRIDOR THROUGH
THE REMAINDER OF THE TAF PERIOD. BY MID MORNING...LIGHT WINDS WILL
LIKELY BACK FROM THE WEST SOUTHWEST. DURING THE MID TO LATE
AFTERNOON...A FEW SHRA OR TSRA MAY DEVELOP ACROSS THE
FOOTHILLS...COVERAGE TOO LIMITED TO MENTION AT KHKY OR KCLT.

AT KAVL...CLEAR AND CALM CONDITIONS COULD RESULT IN RADIATIONAL FOG
NEAR KAVL BEFORE 13Z. I WILL USE A TEMPO FROM 12Z-13Z TO HIGHLIGHT
SCT LIFR CLOUDS AND 6SM BR. OTHERWISE...CONDITIONS WILL REMAIN
UNLIMITED WITH AFTERNOON CONVECTION ACROSS THE RIDGES. IF RAIN
OCCURS AT THE TERMINAL...FOG WILL BE HIGHLY LIKELY. AT THIS TIME...I
WILL INDICATE MVFR BR FROM 9Z THROUGH THE REMAINDER OF THE TAF.

OUTLOOK...THE AIRMASS WILL MOISTEN OVER THE WEEKEND TO SUPPORT ISOLD
TO SCT DIURNAL THUNDERSTORMS...ESPECIALLY ACROSS THE MTNS. MORNING
LOW CLOUDS AND FOG WILL REMAIN POSSIBLE DURING THE EARLY
MORNING...ESPECIALLY IN THE MTN VALLEYS.

CONFIDENCE TABLE...

            10-16Z        16-22Z        22-04Z        04-10Z
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...PM
NEAR TERM...NED
SHORT TERM...PM
LONG TERM...PM
AVIATION...NED






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