Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 251753
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
153 PM EDT MON MAY 25 2015

.SYNOPSIS...
HIGH PRESSURE WILL SLIDE FARTHER EAST INTO THE ATLANTIC...TAKE ON A
MORE SUMMER-LIKE BERMUDA HIGH PATTERN...AND 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 TUESDAY/...
AS OF 145 PM EDT...AN INCREASINGLY MOIST BOUNDARY LAYER IS PROVIDING
PLENTY OF LOWER LEVEL CONVECTIVE CLOUD COVER OVER THE WRN CAROLINAS
AND NE GA THIS AFTN...BUT REGIONAL RADARS ARE QUIET THUS FAR WITH
SOME CAPPING LINGERING IN THE PROFILES. THE CAP WILL FURTHER
DIMINISH OVER WRN SECTIONS DURING THE LATE AFTN AND SRLY UPSLOPE
SHOULD PROVIDE SOME SCATTERED CONVECTION IN SW SECTIONS THROUGH THE
EVENING HOURS. ANTICIPATE SLIGHTLY IMPROVING UPPER LEVEL DIVERGENCE
OVER THE REGION OVERNIGHT AS AN UPPER LEVEL JETLET LIFTS NWD ALONG
THE APPALACHIANS. IN ADDITION...WEAK SHORTWAVES WILL RIDE NORTHWARD
ALONG THE SRN APPALACHIANS IN THE DEEP LAYER S/SW FLOW EAST OF THE
MAIN TROUGH AXIS OVER THE PLAINS. ALSO...MOIST LOW LEVEL SRLY
UPSLOPE FLOW INTO THE HIGHER TERRAIN WILL INCREASE OVERNIGHT. THIS
SHOULD COME TOGETHER TO YIELD BETTER COVERAGE OVERNIGHT IN THE WRN
HALF DURING THE LESS FAVORED DIURNAL PERIOD. FORTUNATELY...
INSTABILITY SHOULD BE FAIRLY WEAK OVER THE MTNS WHERE COVERAGE WILL
BE BEST. ANTICIPATE MILD MINS ON THE WARM SIDE OF GUIDANCE GIVEN THE
EXPECTED CLOUDS AND LIGHT SRLY MIXING FLOW.

MORNING LOW CLOUDS WILL ALLOW SFC HEATING AND INSTABILITY TO GET OFF
TO A VERY SLOW START ON TUESDAY. TEMPERATURES SHOULD ONCE AGAIN
STRUGGLE INTO THE 80S EAST OF THE MTNS AND UPPER 70S IN THE MTN
VALLEYS...AS CUMULUS FILLS IN AS THE LOWER CLOUDS LIFT AND SCATTER.
ANOTHER SHOT OF DEEPER MOISTURE AND LIFT WILL MOVE OVER THE FAR SW
MTNS ON TUESDAY AFTN...WHERE LOW LEVEL SW UPSLOPE FLOW WILL BE
ENHANCED. IN ADDITION...CONVECTION GENERATING AHEAD OF THE LIFTING
WAVE ACROSS THE CENTRAL/LOWER MS RIVER VALLEY WILL MAKE A RUN
EASTWARD THROUGH THE DAY...POSSIBLY TRIGGERING ADDITIONAL CONVECTION
ACROSS THE DEEP SOUTH...AND PERHAPS APPROACHING THE SRN APPALACHIANS
LATE. A SHARP W TO E GRADIENT IN LATE DAY POPS WILL BE ADVERTISED.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
AS OF 145 PM MONDAY...NOT MUCH CHANGE IN EARLIER THINKING AS THE
LATEST MODEL GUIDANCE SHOWS A MOIST FLOW OUT OF THE GULF PERSISTING
AS AN UPPER RIDGE/ANTICYCLONE REMAINS NEARLY STATIONARY OFF THE
SOUTHEAST COAST AND AN UPPER TROF DEAMPLIFIES AND LIFTS NE ACROSS
THE MIDWEST THRU THE MIDDLE PART OF THE WEEK. THUS...ONCE AN AXIS OF
HIGHER PW AIR MOVES OVER THE WRN CAROLINAS AND NE GEORGIA...IT WILL
REMAIN THERE...PROVIDING THE FUEL FOR SHOWERS/TSTMS. THE MODELS
SUGGEST THAT WEAK IMPULSES WILL LIFT NE ACROSS THE REGION THAT WILL
ENHANCE CONVECTIVE POTENTIAL. WHAT IS LESS CERTAIN IS TIMING OF
THESE FEATURES. WHILE DIURNAL ENHANCEMENT IS EXPECTED...THE PRECIP
SHOULD NOT ENTIRELY DIE OFF EACH NIGHT. THAT MIGHT BE ESPECIALLY
TRUE TUESDAY NIGHT. THE CONVECTION ALLOWING MODEL GUIDANCE RUNS THAT
END RIGHT AROUND 00Z WEDNESDAY SHOW A CONVECTIVE BAND MOVING IN FROM
THE W AT THAT TIME...SO EXTRAPOLATION OF THAT FEATURE WOULD BRING A
BETTER CHANCE OF SHOWERS/STORMS ACROSS THE FCST AREA ON TUESDAY
EVENING COMPARED TO THE DAYTIME PERIOD. THE ORGANIZATION OF THE
CONVECTION ALSO SUGGESTS SOME NON-ZERO THREAT FOR SEVERE TSTMS THRU
THE TUESDAY EVENING HOURS. WE ARE LEFT WITH A FCST THAT FAVORS
LIKELY POP OVER THE MTNS AND CHANCE POP OVER THE PIEDMONT FOR MOST
OF THE PERIOD...WHICH IS A BIT DECEPTIVE IN THAT IT MIGHT IMPLY A
CONTINUAL THREAT. IN REALITY...THERE WILL BE LONG STRETCHES WHEN
NOTHING HAPPENS...IT IS JUST NOT POSSIBLE RIGHT NOW TO PIN DOWN WHEN
THE SHOWERS/STORMS WILL PASS. THE BEST THREAT FOR SEVERE WEATHER
AFTER TUESDAY EVENING STILL LOOKS LIKE LOCALLY HEAVY RAIN OWING TO
THE HIGH MOISTURE CONTENT OF THE AIR MASS. TEMPS WILL BE A CATEGORY
OR SO ABOVE NORMAL EACH DAY...BUT WELL ABOVE NORMAL AT NIGHT BECAUSE
OF THE MOIST AIR MASS.

&&

.LONG TERM /THURSDAY NIGHT 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 /18Z MONDAY THROUGH SATURDAY/...
AT KCLT...CCL HEIGHTS CONTINUE TO SUPPORT SCATTERED TO BROKEN
CUMULUS AT 45 TO 50 KFT THROUGH THE LATE AFTERNOON HOURS. AS THE
CUMULUS FIELD WEAKENS LATE THIS EVENING...LOWER LEVEL MOISTURE WILL
ALLOW MVFR CIGS TO FILL IN THROUGH THE EARLY OVERNIGHT HOURS...WITH
IFR QUITE POSSIBLE LEADING UP TO DAYBREAK. THE GFS/LAMP ARE MORE
BULLISH ON THE IFR CLOUDS...WHILE THE NAM HAS MORE SRLY FLOW MIXING
AND CONTINUED MVFR...BUT THE SFC WINDS ON THE NAM MAY BE TOO ROBUST.
WILL THUS CONTINUE THE PREVIOUS FORECAST OF DEVELOPING OVERNIGHT IFR
TOWARD 09Z. ANY CONVECTION SHOULD STAY WELL WEST OF THE AIRFIELD AS
A WEAK MID LEVEL CAP REMAINS THROUGH THE PERIOD. ANTICIPATE FAIRLY
STEADY SRLY SFC WINDS THROUGHOUT...SLIGHTLY HIGHER DURING PERIODS OF
DEEPER MIXING...BUT GENERALLY 10 KT OR LESS WITH ONLY INFREQUENT LOW
END GUSTS.

ELSEWHERE...EXPECT MAINLY LOWER VFR CIGS WITH CUMULUS FROM HEATING
THIS AFTN AND EVENING. MOIST SRLY UPSLOPE FLOW WILL ALLOW MVFR CIGS
TO FILL BACK IN LATE THIS EVENING AND OVERNIGHT...WITH A PERIOD OF
IFR LIKELY BEFORE DAYBREAK. ANY UPSLOPE INDUCED SHOWERS WILL BE
GENERALLY ISOLD TO SCATTERED LATE THIS AFTN...BUT COVERAGE COULD
ACTUALLY INCREASE OVERNIGHT AS BETTER UPPER SUPPORT SWINGS OVER THE
MTN CHAIN. WILL CONTINUE THE MENTION OF VCSH AND TARGETED PROB30 FOR
THE BEST CHANCE PERIODS. THE LOW CLOUDS WILL BE SLOW TO
IMPROVE...WITH RESTRICTIONS LIKELY THROUGH THE LATE MORNING HOURS.
EXPECT SRLY FLOW AROUND 10 KT OR LESS THROUGHOUT...WITH OCNL LOW END
GUSTS THIS AFTN AT KAVL.

OUTLOOK...S TO SW FLOW MOISTURE WILL CONTINUE TO STREAM ACROSS THE
TERMINAL FORECAST AREA THROUGH THE WEEK. EXPECT INCREASED MORNING
STRATUS TO RESULT...WITH BETTER THAN CLIMATOLOGICAL CHANCES OF
MAINLY AFTN/EVENING SHRA/TSRA EACH DAY. HOWEVER...PASSING UPPER
LEVEL DISTURBANCES COULD GENERATE A FEW TSTMS AT NIGHT.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH  81%     HIGH  90%
KGSP       HIGH 100%     HIGH  99%     HIGH  94%     HIGH  98%
KAVL       HIGH 100%     HIGH  96%     HIGH  90%     HIGH  87%
KHKY       HIGH 100%     HIGH 100%     MED   73%     HIGH  94%
KGMU       HIGH 100%     HIGH  97%     HIGH  94%     HIGH  98%
KAND       HIGH 100%     HIGH  98%     HIGH  88%     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/HG
NEAR TERM...HG
SHORT TERM...PM
LONG TERM...ARK
AVIATION...HG


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