Flash Flood Warning 45, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
327 AM EDT THU AUG 19 2010

.SYNOPSIS...
A SLOW MOVING FRONT WILL PUSH SOUTH OF THE AREA LATER TODAY
WITH DRIER WEATHER EXPECTED ON FRIDAY. UNSETTLED WEATHER RETURNS AS
ANOTHER WEAK COLD FRONT APPROACHES THE CAROLINAS OVER THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
A BUSY NEAR TERM IN STORE...AT LEAST FOR THE MORNING HOURS. A
MESOSCALE VORT CENTER WILL HELP TO KICK OFF NUMEROUS TO WIDESPREAD
SHOWERS AND THUNDERSTORMS THROUGH DAYBREAK ALONG AND IMMEDIATELY TO
THE SOUTH OF THE SURFACE BOUNDARY STALLED MORE OR LESS W TO E ACROSS
THE FORECAST AREA. THE AIR MASS ALONG AND S OF THE FRONT REMAINS
RICH WITH MOISTURE...AS HAS BEEN THE CASE ALL WEEK...SO THE MAIN
CONCERN CONTINUES TO BE THE POTENTIAL FOR FLASH FLOODING. LOW LEVEL
FLOW IS A BIT MORE SW TODAY SO UPSLOPE IS LESS OF A CONCERN...BUT
THE FLOW IS MORE PARALLEL TO THE BOUNDARY SO TRAINING ECHOES IS MORE
OF A CONCERN. THE EXISTING FLASH FLOOD WATCH WILL BE KEPT INTACT AND
MIGHT NEED TO BE EXPANDED EAST INTO METRO CHARLOTTE DEPENDING ON
CONVECTIVE EVOLUTION. WITH THE BOUNDARY DRIFTING ACROSS THE REGION
TODAY...PRECIP CHANCES WILL BE VERY HIGH. MAX TEMPS WERE NUDGED
TOWARD A GUIDANCE BLEND.

LATER TODAY...A COLLECTION OF SHORT WAVES OVER THE MIDWEST AND OH
VALLEY SHOULD DIVE DOWN AND DEEPEN AN UPPER TROF ON THE EAST
COAST...WHICH SHOULD FINALLY PUSH THE SURFACE FRONT SOUTHEAST ACROSS
THE FORECAST AREA. PRECIP CHANCES WERE CONSEQUENTLY TAPERED FROM NW
TO SE THIS EVENING. DRIER AIR SEEN ON WATER VAPOR IMAGERY IS
EXPECTED TO SPREAD IN FROM THE NW OVERNIGHT. MEANWHILE...WE SHOULD
RETAIN PLENTY OF LOW LEVEL MOISTURE. THIS SHOULD RAISE THE POTENTIAL
FOR DENSE FOG EARLY FRIDAY MORNING AND EXPECT WE WILL NEED AN
ADVISORY FOR AT LEAST SOME PART OF THE AREA. LOW TEMPS WERE NUDGED
TOWARD THE MAV NUMBERS.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
AS OF 245 AM THURSDAY...POST FRONTAL AIRMASS AND LLVL ENELY FLOW
EXPECTED ACRS THE CWFA ON FRIDAY...ALTHOUGH SHORT RANGE MODEL
GUIDANCE IS AT ODDS WITH HOW FAR SW THE DEGREE OF EFFECTIVE CAPPING
UNDER THE UPPER RIDGING PROGRESSES. EVEN THE GFS DEPICTION HIGHER
AFTERNOON SFC DWPTS...YIELDING WEAK POS CAPE ON MTN/UPSTATE FCST
SNDGS...WOULD PROMPT JUST ISOLATED DEEP CONVECTIVE CHANCES SW OF
I-26. OTHERWISE...THE JUICY AND HUMID AIRMASS OF RECENT DAYS WILL BE
REPLACED WITH NOTABLY DRIER AIR DESPITE MAX TEMPS REBOUNDING TO
ABOVE CLIMO. WITH SOME DEGREE OF DEEPER MOISTURE LINGERING CLOSER TO
LLVL CONVERGENCE ZONE JUST SW OF THE CWFA...WILL HAVE TO LINGER
SHOWER CHANCES INTO THE NIGHT WITHIN THE POTENTIALLY VEERED 925-85H
FLOW. THE TREND THROUGH SATURDAY WILL FEATURE CONTINUED MOISTURE
ENCROACHMENT AS LLVL FLOW BECOMES INCREASINGLY SE AND TAD BIT MORE
STOUT. MORNING SHOWER CHANCES...MAINLY WEST OF I-26...SHOULD INCREASE
IN CVRG AND DEVELOP INTO TSTMS AS THE DAY WEARS ON WITH DEEP
CONVECTIVE POTENTIAL REACHING TO ABOUT I-77...BEFORE ENCOUNTERING
THE LINGERING STABLE AIR IN CENTRAL NC.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 320 AM THURSDAY...BOTH THE 00 UTC RUNS OF THE OP GFS AND ECMWF
DEPICT A DEGREE OF DEVELOPING EASTERN CONUS TROUGH SUNDAY ALONG WITH
WEAKENING SFC RIDGING AND CONVECTIVE RESPONSE. APPROACHING
ATTENDANT COLD REMAINS SLATED FOR A MONDAY PASSAGE. INHERITED FCST OF
CLIMO MAX TEMPS AND CHANCE POPS STILL LOOK GOOD FOR DAYS 4/5. IT ALSO
LOOKS NOT A CERTAINTY THAT THE PUSH OF DEEP DRYING IN WAKE OF COLD
FRONT WILL BE ENOUGH TO EFFECTIVELY CAP POPS ON TUESDAY AND
WEDNESDAY...SO WILL STICK WITH GOING SLIGHT CHANCE AND MAX TEMPS
NOT FAR FROM NORMAL.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
AT KCLT...A BUSY NIGHT AS AN UPPER WAVE IS HELPING TO FORCE
NOCTURNAL THUNDERSTORMS AND SHOWERS ACROSS THE PIEDMONT. EXPECT
SHOWERS AND STORMS TO FILL IN A BAND RUNNING ALONG AND N OF I-85
THROUGH THE NEXT FEW HOURS...AND WILL HAVE TO MONITOR THE DRIFT OF
THIS BAND BECAUSE IT WILL BE CLOSE. IF THE STEADY RAIN STAYS N... WE
CAN STILL EXPECT A FEW PASSING SHOWERS THAT WILL BRING A BRIEF MVFR
CEILING OR VIS. TOWARD 10Z-11Z...IT SEEMS REASONABLE THAT AN IFR OR
VERY LOW MVFR CEILING WILL DEVELOP ONCE AGAIN...GIVEN THE PERSISTENT
MOISTURE RICH AIR MASS S OF THE FRONT. THAT FRONT SHOULD FINALLY
START MOVING SOUTH AND EAST TODAY ACCOMPANIED BY MORE UPPER
FORCING...SO A FEW SHOWERS AND THUNDERSTORMS ARE EXPECTED TO MOVE
ACROSS THE AIR FIELD AT SOME TIME...MOST LIKELY FROM NOW THROUGH THE
LATE AFTERNOON. ACTIVITY WINDS DOWN A BIT EARLIER THAN THE LAST FEW
DAYS AS THE FRONT DRIFTS S. WIND WILL GENERALLY REMAIN S OR SW APART
FROM ANY THUNDERSTORMS...AND THEN SHIFT TO LIGHT N BEHIND THE
BOUNDARY THIS EVENING.

ELSEWHERE...EXPECT A CONVECTIVELY ACTIVE PERIOD THROUGH MID MORNING
AS AN UPPER DISTURBANCE MOVES THROUGH. TAFS GENERALLY FOLLOW A
PERSISTENT PATTERN WITH IFR/LOW MVFR CEILING DEVELOPING TOWARD
DAYBREAK...BUT EARLY THIS MORNING WE SHOULD SEE CONSIDERABLY MORE
SHOWERS AND STORMS. WILL AMEND TAFS AS NECESSARY TO HANDLE THE LOW
VIS IN PASSING STORMS. THE PASSAGE OF THE WEAK WAVE COULD SIGNAL AN
EARLY END TO THE NUMEROUS STORMS...BUT A CB WILL CONTINUE TO BE
INCLUDED THROUGH 23Z OR SO. THE WEAK FRONT SHOULD DRIFT SOUTH THIS
EVENING AND EXPECT CONDITIONS TO TEMPORARILY IMPROVE.

OUTLOOK...LOW LEVEL MOISTURE WILL REMAIN HIGH THROUGH THU NIGHT AND
EXPECT RESTRICTIONS DUE TO FOG EARLY FRI...ESPECIALLY MOUNTAIN
VALLEYS. OTHERWISE GENERALLY VFR FRI. SOME RESTRICTIONS WILL RETURN
AGAIN OVER THE WEEKEND WITH SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS. ALSO...EARLY MORNING FOG/STRATUS WILL BECOME MORE
WIDESPREAD BY SUNDAY.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FLASH FLOOD WATCH THROUGH THIS AFTERNOON FOR NCZ033-048>053-
     058-059-062>065-501>507-509.
SC...NONE.

&&

SYNOPSIS...CSH
NEAR TERM...PM
SHORT TERM...CSH
LONG TERM...CSH/NED
AVIATION...ARK/PM

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
926 PM EDT WED AUG 18 2010

GAZ010-017-018-026-028-029-NCZ035>037-056-057-068>072-082-508-510-
SCZ001>014-019-200130-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-ALEXANDER-IREDELL-
DAVIE-CATAWBA-ROWAN-CLEVELAND-LINCOLN-GASTON-MECKLENBURG-CABARRUS-
UNION NC-GREATER RUTHERFORD-EASTERN POLK-OCONEE MOUNTAINS-
PICKENS MOUNTAINS-GREENVILLE MOUNTAINS-GREATER OCONEE-
GREATER PICKENS-GREATER GREENVILLE-SPARTANBURG-CHEROKEE-YORK-
ANDERSON-ABBEVILLE-LAURENS-UNION SC-CHESTER-GREENWOOD-
926 PM EDT WED AUG 18 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST GEORGIA...PIEDMONT
NORTH CAROLINA...WESTERN NORTH CAROLINA AND UPSTATE SOUTH CAROLINA.

.DAY ONE...TONIGHT.

NUMEROUS TO WIDESPREAD SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
DEVELOP OVERNIGHT. LOCALLY HEAVY...IF NOT EXCESSIVE RAINFALL WILL
ACCOMPANY THE STRONGER STORMS. ALSO...A FEW STORMS MAY PRODUCE
FREQUENT LIGHTNING...AND DAMAGING WIND GUSTS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

NUMEROUS SHOWERS AND THUNDERSTORMS WILL BE SEEN AGAIN ON THURSDAY.
THE BIGGEST THREAT WITH STORMS WILL BE A PERIOD OF HEAVY RAIN.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE REQUESTED TO FORWARD ANY REPORTS OF LARGE
HAIL...DAMAGING WINDS...TORNADOES OR FLASH FLOODING TO OUR OFFICE.

NCZ033-048>053-058-059-062>065-501>507-509-200130-
AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-GRAHAM-
NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-HENDERSON-
CALDWELL MOUNTAINS-GREATER CALDWELL-BURKE MOUNTAINS-GREATER BURKE-
MCDOWELL MOUNTAINS-EASTERN MCDOWELL-RUTHERFORD MOUNTAINS-
POLK MOUNTAINS-
926 PM EDT WED AUG 18 2010

...FLASH FLOOD WATCH IN EFFECT THROUGH THURSDAY AFTERNOON...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN NORTH CAROLINA.

.DAY ONE...TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   FLASH FLOOD WATCH.

NUMEROUS TO WIDESPREAD SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
DEVELOP OVERNIGHT. IN ADDITION TO A THREAT FOR EXCESSIVE
RAINFALL...A FEW STORMS MAY PRODUCE FREQUENT LIGHTNING...AND
DAMAGING WIND GUSTS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   FLASH FLOOD WATCH.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE REQUESTED TO FORWARD ANY REPORTS OF LARGE
HAIL...DAMAGING WINDS...TORNADOES OR FLASH FLOODING TO OUR OFFICE.