Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 251145
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
745 AM EDT MON MAY 25 2015

.SYNOPSIS...
HIGH PRESSURE WILL SLIDE FARTHER EAST INTO THE ATLANTIC AND TAKE ON
A MORE SUMMER-LIKE BERMUDA HIGH PATTERN TODAY.. AND WILL REMAIN
THERE THROUGH THE WEEK. THIS WILL PRODUCE A MOIST SOUTHERLY FLOW
WITH INCREASED CHANCES FOR WIDESPREAD SHOWERS AND THUNDERSTORMS EACH
DAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 655 AM...LOW CLOUDS CONTINUE TO EXPAND ACROSS THE MTNS AND WRN
UPSTATE/NE GA. THESE CLOUDS WILL SLOWLY LIFT THRU THE DAY WITH
CONVECTIVE CU FORMING ALL AREAS DURING THE AFTERNOON. CAM GUIDANCE
CONTINUES TO SUGGEST LOWER COVERAGE UNTIL LATER IN THE AFTERNOON AND
EARLY EVENING WHEN COVERAGE INCREASES ACROSS THE WEST. I-77 CORRIDOR
REMAINS CAPPED WITH NO CONVECTION. OTHERWISE...GOING FCST ON TRACK
WITH UPDATES MAINLY FOR CURRENT CONDITIONS.

AS OF 255 AM...LOW CLOUDS FINALLY FORMING ALONG THE BLUE RIDGE NEAR
THE NC/SC BORDER WEST INTO NE GA. THESE CLOUDS WILL SLOWLY INCREASE
THRU THE MORNING ACROSS THE MTNS AND BLUE RIDGE...AND ALONG AND WEST
OF I-26 ACROSS THE UPSTATE AND NE GA. THE LATEST GUIDANCE DOES NOT
BRING MORE THAN SCT LOW CLOUDS EAST OF THESE AREAS...AND THIS SEEMS
REASONABLE. THAT SAID...THERE ARE SOME LOW CLOUDS MOVING NORTH ALONG
THE SAVANNAH RIVER. THESE SHUD STAY WEST...BUT COULD EXPAND EAST AS
THEY MOVE NORTH. EVEN WHERE CLOUDS DO NOT DEVELOP/MOVE IN...SHUD SEE
QUITE A BIT OF CONVECTIVE CU DEVELOP THRU THE DAY. GUIDANCE IN GOOD
AGREEMENT SHOWING THE UPPER RIDGE AXIS CURRENTLY ACROSS THE AREA
MOVING EAST TO THE COAST TODAY ALLOWING SHORT WAVE ENERGY TO MOVE
ACROSS THE WRN CWFA. THIS COMBINED WITH INCREASING LOW LEVEL
MOISTURE AND INSTABILITY...SHUD LEAD TO SCT CONVECTION ALONG AND
WEST OF I-26 WITH ISOLATED CONVECTION EAST ACROSS THE NRN MTNS...
FOOTHILLS AND PORTIONS OF THE ERN UPSTATE. IT IS INTERESTING THAT
THE LATEST CAM GUIDANCE HOLDS OFF ON THE BEST CONVECTIVE COVERAGE
UNTIL EVENING...WHEN COVERAGE EXPANDS ACROSS THESE AREAS. THE
SYNOPTIC SCALE GUIDANCE HAS TRENDED THIS WAY AS WELL...AND IF HAVE
FOLLOWED SUIT. THAT SAID...ALL GUIDANCE IS IN GOOD AGREEMENT THAT
THE I-77 CORRIDOR WILL REMAIN DRY AS THE SUBSIDENCE INVERSION
ASSOCIATED WITH THE UPPER RIDGE WILL REMAIN IN PLACE. THE CONVECTION
SHUD STILL HAVE A DIURNAL COVERAGE TREND...BUT WILL LIKELY LINGER
THRU THE NITE ACROSS THE WRN CWFA WHERE ADDITIONAL SHORT WAVE ENERGY
AND UPPER DIVERGENCE MOVE THRU IN THE SWLY FLOW ALOFT. EVEN THO
CONVECTIVE COVERAGE WILL BE DECENT ACROSS THE WRN CWFA...CHC OF
SEVERE STORMS REMAINS LOW GIVEN THE WEAK INSTABILITY AND SHEAR.
HIGHS TODAY WILL BE NEAR NORMAL WEST AND A FEW DEGREES ABOVE NORMAL
EAST. LOWS TONIGHT WILL BE NEARLY 10 DEGREES ABOVE NORMAL.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...MODELS IN GOOD AGREEMENT THAT AN AXIS OF HIGH
PWAT AIR WILL STALL ACRS THE CWFA...AS HIGH-AMPLITUDE UPPER RIDGE
REMAINS ANCHORED JUST OFF THE EAST COAST...WHILE A DE-AMPLIFYING
TROF NUDGES EAST. THE CONFLUENT FLOW BETWEEN THESE FEATURES HELP
KEEP PWATS HIGH. BOTH THE NAM AND GFS FCST SNDGS SHOW FAIRLY MOIST
PROFILES WITH WEAK SHEAR AND POTENTIALLY SLOW STORM MOTIONS. UPPER
FORCING REMAINS FAIRLY WEAK...BUT EMBEDDED SHORTWAVE IMPULSES WILL
CROSS THE AREA WITHIN GRADUALLY INCREASING SWLY FLOW ALOFT. SO
EXPECT LARGELY DIURNAL PULSE CONVECTION...WITH LOCALLY HEAVY RAIN
BEING THE MAIN THREAT BOTH TUESDAY AND WEDNESDAY. ALTHO SOME
LINGERING NOCTURNAL CONVECTION IS EXPECTED BOTH TUESDAY AND
WEDNESDAY NIGHTS...WITHIN THE MOIST AIR MASS. POPS WILL BE IN THE
LIKELY TO CATEGORICAL RANGE FROM THE FOOTHILLS WEST...AND GENERALLY
MID TO HIGH CHC EAST. TEMPS WILL BE ABOUT A CATEGORY OR TWO ABOVE
NORMAL FOR AFTN HIGHS...AND ABOUT 6-8 DEG ABOVE NORMAL FOR OVERNIGHT
LOWS.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 245 AM MONDAY...A SHORTWAVE TROF WILL GET SHEARED OUT AS IT
TRIES TO BREAK DOWN THE UPPER RIDGE ALONG THE APPALACHIANS ON
THURSDAY. THE UPPER RIDGE REASSERTS ITSELF ACRS THE REGION SOMEWHAT
BY FRIDAY...AND CONTINUES TO DOMINATE OVER THE SOUTHEAST STATES THRU
THE WEEKEND. OVERALL...THE AREA REMAINS FAIRLY MOIST AND
HUMID...WITH A BERMUDA HIGH PRES SYSTEM REMAINING ANCHORED OVER THE
NORTH ATLANTIC. NEAR OR SLIGHTLY ABOVE NORMAL TEMPS AND CONTINUED
DIURNAL POPS (LIKELY MTNS AND CHC PIEDMONT) ARE EXPECTED THURSDAY
AND FRIDAY. THEN TEMPS WARM A CATEGORY OR TWO FURTHER UNDER THE
BUILDING UPPER RIDGE...WITH POPS A LITTLE LOWER...BUT STILL ABOVE
CLIMO FOR THE WEEKEND.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AT KCLT...SAT PIX SHOW MVFR CIGS REMAIN WEST OF THE AIRFIELD ATTM.
EXPECT THIS TREND TO CONTINUE. HOWEVER...THERE ARE SOME LOW VFR
CLOUDS SOUTH OF THE AIRFIELD AND THESE COULD MOVE OVER FROM TIME TO
TIME BEFORE CONVECTIVE CU DEVELOP FOR THE AFTERNOON. THAT SAID...CHC
OF CIGS ARE LOW UNTIL THE AFTERNOON CU DEVELOP. SUBSIDENCE INVERSION
WEAKENS LATE IN THE DAY BUT APPEARS LIKELY TO HOLD ON ENOUGH TO
PRECLUDE ANY CONVECTION. MUCH BETTER CHC OF RESTRICTIONS TONIGHT AS
GUIDANCE IN GOOD AGREEMENT ON LOW CLOUDS DEVELOPING. EXPECT MVFR
CIGS NEAR MIDNIGHT AND IFR SOON AFTER. SLY WINDS CONTINUE THRU THE
PERIOD.

ELSEWHERE...MVFR CIGS HAVE DEVELOPED WITH COVERAGE INCREASING ACROSS
THE WRN SITES. THERE IS SOME MVFR NEAR KHKY...BUT LOOKS LIKE THEY
SHUD REMAIN SCT. THAT SAID...CANNOT RULE OUT A BRIEF CIG THIS
MORNING. CIGS SHUD LIFT TO VFR WITH HEATING WHILE DIURNAL CU
DEVELOPS AT KHKY. PROB30 RETAINED FOR ALL BUT HKY WHERE ATMOS
REMAINS CAPPED. MVFR CIGS RETURN ALL AREAS MIDNIGHT...WITH MVFR VSBY
AT KAVL AS WELL. IFR CIGS DEVELOP SOON AFTER. S TO SE WINDS THRU THE
PERIOD.

OUTLOOK...MOISTURE WILL CONTINUE TO RETURN OUT OF THE SOUTH THRU THE
MIDDLE OF THE WEEK. INCREASED MORNING STRATUS...AND BETTER THAN
CLIMATOLOGICAL CHANCES OF MAINLY AFTN/EVE SHRA/TSRA ARE EXPECTED
THRU THU. HOWEVER...PASSING UPPER LEVEL DISTURBANCES COULD DRIVE A
FEW STORMS AT NIGHT.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  93%
KGSP       HIGH 100%     MED   66%     HIGH 100%     MED   64%
KAVL       HIGH  87%     MED   66%     HIGH 100%     MED   78%
KHKY       HIGH 100%     LOW   55%     HIGH 100%     MED   78%
KGMU       HIGH 100%     MED   66%     HIGH 100%     MED   64%
KAND       HIGH 100%     MED   72%     HIGH 100%     LOW   48%

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...ARK
NEAR TERM...RWH
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...RWH


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