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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
430 PM EDT FRI AUG 22 2014

.SYNOPSIS...
A BROAD UPPER LEVEL RIDGE OF HIGH PRESSURE WILL CONTINUE TO BRING 
VERY WARM TEMPERATURES TO MUCH OF THE REGION INTO SATURDAY. A BACK 
DOOR COLD FRONT WILL THEN PUSH INTO THE AREA FROM NORTHEAST USHERING 
IN COOLER TEMPERATURES STARTING SUNDAY. TEMPERATURES WILL GRADUALLY 
RETURN TO NORMAL THROUGH NEXT WEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 425 PM...CONVECTION DEVELOPING MUCH SLOWER THAN FORECAST 
ACROSS THE AREA. LIKELY DUE TO LACK OF TRIGGER AND VERY HIGH LFC 
VALUES. HAVE SLOWED THE ONSET OF SCT COVERAGE A COUPLE OF HOURS BUT 
LEFT ISOLATED IN PLACE GIVEN THE ISOLATED COVERAGE NOW DEVELOPING. 
WITH VERY HIGH DCAPE VALUES IN PLACE OVER THE AREA...ANY STORMS THAT 
FORM WILL HAVE THE POTENTIAL FOR STRONG TO EVEN SVR DOWNBURST WINDS. 
THAT SAID...WITH RELATIVELY LOW SHEAR VALUES...ANY SVR STORMS SHUD 
REMAIN ISOLATED WITH LITTLE ORGANIZATION. STILL EXPECT BETTER 
COVERAGE LATER WHEN MCS ACTIVITY APPROACHES...SO NO CHANGES TO LATER 
POP. OTHERWISE...UPDATES FOR CURRENT CONDITIONS.

AS OF 225 PM EDT...WATER VAPOR IMAGERY SHOWS CONVECTION DEVELOPING 
ALL AROUND THE RING OF FIRE THAT STRETCHES FROM KANSAS TO IL TO WEST 
VIRGINIA AROUND THE STRONG CENTRAL CONUS RIDGE. LITTLE TO NO UPPER 
LEVEL TRIGGERING HAS BEEN PRESENT IN OUR FORECAST AREA...AND IT MAY 
TAKE A RUN FROM AN UPSTREAM MCS SEGMENT TO PRODUCE MUCH COVERAGE. 
THE AMPLIFYING UPPER RIDGE IS COOPERATING IN THIS REGARD BY TURNING 
DEEP LAYER STEERING FLOW MORE NWLY TO NRLY WITH TIME. IN ADDITION... 
DECENT HEATING ALONG AND SOUTH OF THE INTERSTATE 40 CORRIDOR...ALONG 
WITH DEWPOINTS PERSISTING IN THE UPPER 60S IN MOST LOCATIONS...HAS 
GENERATED SFC BASED CAPE VALUES OF NEARLY 3000 J/KG TO HELP PRIME 
THE AREA. THE BEST CONSENSUS OF SOLUTIONS IS AN MCS RUNNING SE FROM 
KY TO REACH OUR FORECAST AREA CLOSE TO 00Z AND TRANSITING A PORTION 
OF THE REGION N TO S BEFORE DISSIPATING BY AROUND 06Z. WILL THUS 
FEATURE HIGH CHANCE TO NEAR LIKELY NRN TIER POPS FOR THE 
EVENING...AND DIMINISH SWD...WITH JUST LINGERING WRN NC POPS FOR ANY 
ADDITIONAL WEAK OVERNIGHT ACTIVITY IN THE NW STEERING FLOW. EXPECT 
SULTRY MINS IN THE UPPER 60S IN THE MTN VALLEYS TO LOWER 70S EAST.

A BACKDOOR FRONTAL BOUNDARY WILL MAKE STEADY PROGRESS IN OUR 
DIRECTION FROM THE NE ON SAT...BUT WITH ANY REAL THICKNESS FALLS 
DELAYED UNTIL AFTER THE NEAR TERM PERIOD. NRLY FLOW AND MORE CLOUDS 
WILL ALLOW MAX TEMPS TO FALL A COUPLE OF DEGREES OR MORE DESPITE THE 
CONTINUED WARM LOW LEVEL THICKNESSES. ANOTHER RUN OF ORGANIZED 
CONVECTION WILL BE POSSIBLE SAT AFTN AS ACTIVITY MOVES SOUTHEAST 
ALONG THE BACKDOOR FRONT. IN ADDITION...PRECIPITABLE WATER WILL POOL 
ABOVE 2 INCHES ACROSS THE REGION BY SAT AFTN. HOWEVER...THERE SHOULD 
BE ENOUGH NRLY STEERING FLOW TO KEEP THE HEAVIER RAIN ELEMENTS 
MOVING. ANY TRAINING OF THUNDERSTORMS WOULD BE THE PRIMARY HYDRO 
CONCERN SAT AFTN. LAPSE RATES WILL ACTUALLY BE STEEPER IN SW 
SECTIONS...BUT THE COVERAGE MIGHT BE BETTER IN THE NRN TIER CLOSER 
TO THE FORCING AND WEAK MCS TRACKS. SHOTGUN PM CHANCES POPS SEEMS 
REASONABLE THROUGHOUT.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 1245 PM FRIDAY...THE INHERITED MAGNITUDE OF THE EXPECTED 
COOLDOWN FOR SUNDAY REMAINS ON TRACK WITH THE EXPECTATION OF SFC 
RIDGE BUILDING SWWD IN THE CWFA. ACCOMPANYING LLVL EASTERLY FLOW 
CONTINUES TO PROMISE UNSETTLED WX...ESPECIALLY ACRS THE MTNS/FTHLS 
WHERE THE INSTABILITY WILL BECOME INCREASINGLY CONFINED TO. AN 
INFLUX OF DRIER AIR...FROM NE TO SW ACRS THE REGION...IS PROGGED FOR 
SUNDAY NIGHT AND PRECIP CHANCES WILL WANE ACCORDINGLY. DEEPER 
LAYERED RIDGING AND DRY AIR ATOP THE CWFA SHOULD PROVIDE QUIET WX 
CONDITIONS WITH MAX TEMPERATURES SVRL CATEGORIES BELOW CLIMO ON 
MONDAY. CLOSER TO THE LLVL RIDGE PERIPHERY...SLIGHT CHANCES FOR 
DIURNAL DEEP CONVECTION WILL BE CONFINED TO THE SW NC/N GA MTNS.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 230 PM EDT FRIDAY...LATEST GLOBAL MODELS CONTINUE TO INDICATE 
THAT A SURFACE WEDGE OF HIGH UNDERNEATH A PERSISTING UPPER RIDGE OF 
HIGH ACROSS THE SOUTHEAST STATES WILL KEEP CONDITIONS RELATIVELY DRY 
AND COOL MON NIGHT INTO WED. BY WED NIGHT...THE UPPER PATTERN WILL 
FLATTEN OUT AS AN UPPER TROUGH APPROACHES FROM THE CENTRAL CONUS. 
THE GFS SUGGESTS THAT THE TROUGH AND AN ASSOCIATED COLD FRONT WILL 
PUSH THROUGH THE REGION THU AFTERNOON INTO FRI WHILE THE OLD ECMWF 
STALLS OUT THE FRONT JUST TO OUR NORTH. AT ANY RATE...INCREASING 
MOIST RETURN FLOW AND MARGINAL BUOYANCY ALOFT ARE SUPPORTIVE OF 
LOW END CHANCE FOR CONVECTION DURING THIS PERIOD. TEMPS WILL STAY 
3-5 DEGREES BELOW NORMAL ON TUE AND AROUND NORMAL WED THRU FRI.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...CELL GOING UP NEAR THE AIRPORT HAD SOME IN-CLOUD 
LIGHTNING...SO DID A QUICK AMD FOR TSRA AND AN AWW FOR CG STRIKES. 
OTHERWISE...STILL EXPECT ONLY ISOLATED COVERAGE THRU THE AFTERNOON. 
ANY PRECIPITATION MENTION GOING FORWARD WILL BE ASSOCIATED WITH 
DECAYING MCS ACTIVITY ARRIVING FROM THE NW THIS EVENING. SINCE 
THUNDER IS QUESTIONABLE DEPENDING ON HOW QUICKLY THE SYSTEM 
DISSIPATES...WILL ADVERTISE ONLY VCSH AT THIS POINT. 
OTHERWISE...EXPECT NW WINDS THIS AFTN TO TOGGLE WSW WITH WEAK LEE 
TROUGHING THROUGH THE EVENING HOURS...RETURNING TO NW OR NRLY 
OVERNIGHT INTO SAT. MAINLY SCT CUMULUS ARE EXPECTED EARLY...BUT WITH 
MOISTURE INCREASING IN NRLY FLOW TO PERMIT VFR CIGS TO DEVELOP 
TONIGHT AND PERSIST SAT WITH AN APPROACHING BACKDOOR COLD FRONT.

ELSEWHERE...SIMILAR TO KCLT...WILL HAVE TO WATCH THE ISOLATED TSRA 
THIS AFTERNOON FOR ANY AMD. THEN...ALL EYES WILL BE ON CONVECTIVE 
ACTIVITY DEVELOPING FROM TN TO ERN KY TO WV TO SEE WHAT CAN RUN INTO 
OR NEAR THE TERMINAL FORECAST AREA THIS EVENING. IT STILL APPEARS 
THE BEST CHANCE OF VCTS WILL RANGE FROM AS EARLY AS 22Z IN THE FAR 
NRN TIER TO PERHAPS AS LATE AS 06Z IN FAR SRN SECTIONS. EXPECT 
MAINLY NW FLOW IN WRN NC...TURNING MORE NRLY WITH TIME. WINDS MAY 
BRIEFLY TOGGLE WSW OR SW IN THE UPSTATE WITH WEAK LEE 
TROUGHING...BUT WITH A RETURN TOWARD NRLY OVERNIGHT INTO SAT. 
MOISTURE WILL INCREASE IN THE NRLY FLOW THROUGH THE MORNING ON 
SAT...WITH VFR CIGS LIKELY AS A BACKDOOR COLD FRONT APPROACHES. ANY 
FOG AT KAVL AT DAYBREAK SHOULD BE MVFR AT WORST.

OUTLOOK...A BACKDOOR COLD FRONT WILL SAG INTO THE REGION THROUGH THE 
WEEKEND...WITH CHANCES OF RESTRICTIONS INCREASING AT KHKY AND KAVL 
THROUGH SUNDAY. A MORE DIURNAL PATTERN OF EARLY MORNING LOW 
CLOUDS/FOG AND ISOLD AFTN TSTMS MAY RETURN EARLY NEXT WEEK...WITH 
STEADY DRYING.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-20Z 
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%     
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%     
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%     
KHKY       HIGH 100%     HIGH 100%     HIGH  95%     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/RWH
SHORT TERM...CSH
LONG TERM...JOH
AVIATION...HG/RWH




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