Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS62 KGSP 312113
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
513 PM EDT SUN AUG 31 2014

.SYNOPSIS...
A BERMUDA HIGH WILL REMAIN IN PLACE THROUGH EARLY IN THE
WEEK... RESULTING IN TYPICAL SUMMERTIME HEAT AND ISOLATED TO
SCATTERED AFTERNOON THUNDERSTORMS EACH DAY.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 445 PM EDT...CONVECTIVE COVERAGE LATE THIS AFTN HAS FOCUSED
MAINLY ALONG TWO CONVERGENCE AXES...ONE ALONG THE EASTERN SLOPES OF
THE MTNS AND ANOTHER IN THE LOWER PIEDMONT JUST SE OF KCLT.
CONTINUED SCATTERED TRIGGERING IS EXPECTED IN THESE AREAS...WITH
ISOLD TO SCT COVERAGE DOWNSTREAM IN THE SW TO WSW STEERING FLOW
ALOFT. POPS AND QPF HAVE BEEN BOOSTED IN THESE AREAS ACCORDINGLY.
HEAVY RAIN IS A THREAT UNDER ANY CELLS THAT FORM GIVEN THE FAIRLY
HIGH PRECIPITABLE WATER VALUES...BUT THERE IS ENOUGH STEERING FLOW
THAT ONLY TRAINING WOULD CAUSE ISSUES. ALSO...20 TO 30 KT OF LOW
LEVEL FLOW IS SHOWING UP ON VAD WIND PROFILES TO THE W...AND SLIGHT
ORGANIZATION OF CELLS WILL BE POSSIBLE OVER THE MTNS...BUT THE
SEVERE TSTM RISK REMAINS FAIRLY LOW OVERALL IN THE LIMITED DCAPE AIR
WITH HIGH FREEZING LEVELS.

OTHERWISE...BERMUDA HIGH WILL REMAIN STRONG THROUGH TONIGHT AND
MONDAY...THOUGH NUMEROUS MESOSCALE UPPER DISTURBANCES WILL PASS BY
ON ITS NW FRINGE AS THEY EXIT THE CENTRAL CONUS TROUGH. THESE
DISTURBANCES LARGELY SHOULD LEAVE OUR CWFA UNSCATHED...WITH THE
NRN MTNS MOST LIKELY TO SEE AN IMPACT ON CONVECTIVE COVERAGE. UNDER
THE RIDGE...LAPSE RATES WILL REMAIN MARGINAL FOR DEEP CONVECTION
WITH SOME DEGREE OF MIDLEVEL CAPPING THROUGH MONDAY. A PASSING VORT
MAX THIS EVENING MIGHT ALLOW CONVECTION TO CONTINUE NEAR THE TN
BORDER PAST THE END OF HEATING...BUT ELSEWHERE THE FCST IS DRY
OVERNIGHT.

SKY COVER IS A TOUGH CALL FOR TONIGHT BUT IT APPEARS THERE IS LITTLE
SUPPORT FOR WIDESPREAD LOW CLOUDS. PATCHY MID-HIGH CLOUDS ARE LIKELY
HOWEVER. DEWPOINTS AND CROSSOVER TEMPS ARE BOTH HIGH DUE TO THE
MOIST LLVL CONDITIONS. FAVORING LIGHTER MOS WINDS...PATCHY FOG IS
LIKELY ACRS MUCH OF THE REGION DESPITE LIMITED COOLING ON ACCOUNT OF
THE MOIST CONDITIONS. TEMPS WILL BOTTOM OUT A COUPLE DEGREES ABOVE
NORMAL. MORE MIXING IS EXPECTED TOMORROW SO RH SHOULD BE A LITTLE
MORE TOLERABLE...WITH HIGHS A LITTLE ABOVE NORMAL.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 215 PM SATURDAY...TYPICAL LATE SUMMER WEATHER IS EXPECTED
THROUGH THE SHORT TERM...AS SUBTROPICAL/BERMUDA HIGH PRESSURE
GENERALLY MAINTAINS ITS HOLD ACROSS THE SOUTHEAST. A SHORT WAVE
TROUGH PASSING NORTH OF OUR REGION LATE TUE. ASSOCIATED COLD FRONT
WILL APPROACH THE SOUTHERN APPALACHIANS FROM THE TENN VALLEY TUE
EVENING... POSSIBLY ENHANCING CONVECTIVE CHANCES ACROSS THE NC MTNS
DURING THIS TIME. HOWEVER...WITH THE PRIMARY SYNOPTIC SCALE FORCING
PASSING BY TO OUR NORTH...WEAK SHEAR...AND WEAKENING INSTABILITY
ASSOCIATED WITH THE NOCTURNAL COOLING CYCLE...IT/S NOT CLEAR HOW
LONG INTO TUE NIGHT CONVECTION WILL CONTINUE BEFORE DISSIPATING.
CHANCE POPS HAVE GENERALLY BEE LIMITED TO THE EVENING HOURS.

THE FRONT IS EXPECTED TO INTRODUCE A SLIGHTLY COOLER/SLIGHT DRIER
AIR MASS TO THE AREA...WITH TEMPS EXPECTED TO TOP OUT CLOSER TO
CLIMO FOR WED AFTERNOON. IT DOES NOT APPEAR THAT ANY DRYING WILL BE
SUBSTANTIAL ENOUGH TO PRECLUDE AFTERNOON DESTABILIZATION AND DIURNAL
CONVECTIVE DEVELOPMENT. NEAR-CLIMO POPS (LOW CHANCE MTNS/SLIGHT
CHANCE EAST) WILL BE ADVERTISED WED AFTERNOON.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 230 PM EDT SUNDAY...LATEST GLOBAL MODELS HAVE TRENDED WEAKER
UPPER RIDGING ACROSS THE SOUTHERN CONUS...LEADING TO INCREASING
CHANCES FOR CONVECTION THROUGHOUT THE MEDIUM RANGE PERIOD. WED NIGHT
THRU FRI...MODELS STILL DEPICT UPPER RIDGING AMPLIFYING ACROSS THE
REGION THRU THU...THEN WEAKENS BY FRI IN RESPONSE TO A NORTHERN
UPPER TROUGH TRAVERSING THE UPPER MIDWEST. A FRONTAL BOUNDARY JUST
TO OUR SOUTH WILL BE WASHED OUT BY THURSDAY AS A BERMUDA HIGH
RE-BUILDS ACROSS THE SOUTHEAST AND REMAIN IN PLACE THRU FRI. DESPITE
THE UPPER RIDGING ALOFT...ATLANTIC MOISTURE INFLUX AND MODERATE
DIURNAL BUOYANCY (1500-2500J/KG SBCAPE) WILL BE SUPPORTIVE OF
SCATTERED CONVECTION. HENCE...HAVE UPDATED POPS TO INCREASE TO
AROUND 40-50 RANGE. SAT AND SUNDAY...THE UPPER RIDGE FLATTENS OUT
OVER THE SOUTHEAST AS THE UPPER TROUGH MOVES ACROSS THE GREAT LAKES
REGION SAT AND INTO THE OHIO VALLEY BY SUN. THIS WILL ALLOW COOLER
SURFACE HIGH TO SLIDE SOUTH...PUSHING A BACK DOOR COLD FRONT THROUGH
THE FORECAST AREA BY SAT NIGHT/EARLY SUN. WITH GOOD LLVL
CONVERGENCE...UPPER DPVA...MOIST PROFILE AND MODERATE
INSTABILITY...WE SHOULD SEE RATHER ACTIVE WEATHER PATTERN WITH HEAVY
RAINFALL BEING THE PRIMARY THREAT ATT. TEMPS WILL BE AROUND 2-3
DEGREES ABOVE NORMAL THURSDAY AND NEAR NORMAL FRI INTO SUN.

&&

.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
AT KCLT...ANTICIPATE SHRA/TSRA COVERAGE TO REMAIN EAST OF THE
AIRFIELD IN BETTER LOW LEVEL CONVERGENCE...BUT IT COULD BE CLOSE
INTO THE EARLY EVENING HOURS. SFC WINDS SHOULD REMAIN SW EXPECT WITH
ANY BRIEF AND WEAK OUTFLOWS NEARBY. HUMID AFTN CONDITIONS WILL KEEP
CROSSOVER TEMPS SUFFICIENTLY HIGH FOR A FOG RISK LATE TONIGHT...WITH
MVFR EXPECTED AT WORST. WINDS SHOULD COME UP FROM THE WSW MONDAY
MRNG.

ELSEWHERE...BERMUDA HIGH WILL PRODUCE UNFAVORABLE LAPSE RATES AND
MINIMIZE DIURNAL SHRA/TSRA AWAY FROM THE MTNS...BUT SCT CELLS WILL
BE ABLE TO DEVELOP IN THE MTNS ALONG THE FRINGE OF THE HIGH. VCTS
WILL CONTINUE AT KAVL INTO EARLY EVENING...AND SOME OF THIS ACTIVITY
COULD THREATEN KHKY IN THE SW TO WSW STEERING FLOW ALOFT. EXPECT VFR
CONDITIONS AWAY FROM ANY TSRA THROUGH EVENING. OTHERWISE...CIGS ARE
GENERALLY UNLIKELY OVER THE TERMINALS THROUGH THE NIGHT. MTN VALLEYS
HOWEVER ARE EXPECTED TO SEE IFR VSBY DEVELOP IN FOG TOWARD
DAWN...PERHAPS BRINGING LOWER CIGS THERE. MVFR FOG POSSIBLE
ELSEWHERE DUE TO CONTINUED MOIST CONDITIONS AND LIMITED MIXING THIS
AFTN KEEPING CROSSOVER TEMPS HIGH. MAINLY SWLY WINDS ACRS THE AREA
THRU THE PERIOD...BUT PERIODS OF VARIABILITY LIKELY AT KAVL DUE TO
VALLEY EFFECTS IN THIS FLOW.

OUTLOOK...GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THE
WEEK...BUT RESTRICTIONS ARE POSSIBLE EARLY EACH MORNING DUE TO LOW
CLOUDS AND FOG...PRIMARILY IN THE MOUNTAIN VALLEYS. DIURNALLY DRIVEN
SHRA/TSRA ARE EXPECTED EACH AFTERNOON WITH THE MOST COVERAGE OVER
THE MOUNTAINS.

CONFIDENCE TABLE...

            21-03Z        03-09Z        09-15Z        15-21Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH  87%     HIGH 100%
KAVL       HIGH 100%     HIGH  91%     MED   79%     HIGH 100%
KHKY       HIGH 100%     HIGH  95%     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...JOH
NEAR TERM...HG/WIMBERLEY
SHORT TERM...JDL
LONG TERM...JOH
AVIATION...HG/WIMBERLEY






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.