Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 250714
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
314 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 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 /07Z MONDAY THROUGH FRIDAY/...
AT KCLT...ALL GUIDANCE...EVEN THE USUALLY RELIABLE NAM...HAVE BACKED
OFF ON THE AMOUNT OF LOW LEVEL MOISTURE MOVING INTO THE AREA BY
DAYBREAK. THEREFORE...HAVE BACKED OFF ON THE AMOUNT OF LOW CLOUDS IN
THE TAF. THAT SAID...STILL CANNOT RULE OUT SOME LOW VFR CIGS
DEVELOPING AFTER DAYBREAK...BUT THE MAIN THREAT WILL BE DEVELOPING
DIURNAL CU. SUBSIDENCE INVERSION WEAKENS LATE IN THE DAY BUT APPEARS
LIKELY TO HOLD ON ENOUGH TO PRECLUDE ANY CONVECTION. GUIDANCE DOES
AGREE ON LOW CLOUDS DEVELOPING AROUND MIDNIGHT...SO HAVE GONE WITH
MVFR CIGS. GENERALLY SLY WINDS CONTINUE THRU THE PERIOD.

ELSEWHERE...AS WITH KCLT...GUIDANCE HAS BACKED OFF ON LOW CLOUDS
EXCEPT AT KAND...BUT DOES GO WITH LOW VFR CIGS FOR THE FOR ALL BUT
KHKY. HAVE FOLLOWED THESE TRENDS. EXPECT LOW VFR CIGS TO CONTINUE
THRU THE DAY AS CIGS LIFT WITH HEATING AND DIURNAL CU DEVELOPING.
PROB30 RETAINED FOR ALL BUT HKY WHERE INSTABILITY DOES NOT DEVELOP.
AS WITH KCLT...MVFR CIGS DEVELOP AROUND MIDNIGHT...WITH MVFR VSBY AT
KAVL AS WELL. 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...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  92%
KGSP       HIGH 100%     HIGH  89%     HIGH 100%     HIGH  92%
KAVL       HIGH  92%     HIGH  89%     HIGH  97%     HIGH  83%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  91%
KGMU       HIGH 100%     HIGH  87%     HIGH 100%     HIGH  91%
KAND       HIGH 100%     HIGH  89%     HIGH 100%     HIGH  88%

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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