Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
762
FXUS62 KGSP 031857
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
257 PM EDT TUE MAY 3 2016

.SYNOPSIS...
A COLD FRONT WILL MOVE SLOWLY EAST OF THE AREA THROUGH TONIGHT. A
COOLER AND DRIER AIR MASS WILL MOVE IN BEHIND THE FRONT ON
WEDNESDAY. ANOTHER COLD FRONT WILL CROSS THE REGION WEDNESDAY NIGHT
AND USHER IN A MUCH COOLER AIR MASS FROM CANADA FOR THE END OF THE
WORK WEEK. HIGH PRESSURE SHOULD RETURN WITH A WARMING TREND FOR THE
BALANCE OF THE WEEKEND...WITH A FRONT SLOWLY APPROACHING FROM THE
NORTH.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 300 PM...WITH COORDINATION WITH SPC...WE HAVE ISSUED A SEVERE
THUNDERSTORM WATCH FOR THE I-77 CORRIDOR THRU 9 PM THIS EVENING.
STORMS ARE EXPECTED REMAIN GENERALLY DISCRETE WITH ENOUGH SHEAR FOR
SOME SUPERCELLS. DAMAGING WIND AND LARGE HAIL WILL BE THE MAIN
THREATS...AS LLVL SHEAR IS TOO WEAK FOR A TORNADO THREAT.

OTHERWISE...SCATTERED CONVECTION HAS FIRED ACROSS THE EASTERN
BLUE RIDGE ESCARPMENT...FAVORING AN AREA OF ENHANCED CONVERGENCE
ROUGHLY ALONG THE NC/SC BORDER. THE CAMS ARE IN GENERAL AGREEMENT ON
THIS ACTIVITY AFFECTING THE CHARLOTTE METRO AREA LATER THIS AFTN. SO
HAVE LIKELY POPS THERE. THE REST OF THE CWFA LOOKS TO SEE MAINLY
ISOLATED TO SCATTERED CONVECTION AS FORCING IS WEAK TO MODEST AND
CAPE IS ONLY 1000-1500 J/KG. STILL...BULK SHEAR IS SUPPORTIVE FOR
THE STRONGEST CELLS TO GAIN ROTATING UPDRAFTS. THE POTENTIAL FOR A
COUPLE SEVERE STORMS IS MAINLY ACROSS THE I-77 CORRIDOR THIS AFTN TO
EARLY EVENING.

LATER TONIGHT...A COLD FRONT SHOULD PUSH EAST OF THE AREA...AND 850
MB FLOW WILL PICK UP OUT OF THE NW. DRIER AIR WILL WORK IN AND
SHOULD CUT OFF POPS TO JUST ALONG THE TN BORDER THANKS TO UPSLOPE BY
DAYBREAK WEDNESDAY. THIS WILL BE IN SPITE OF A MORE POTENT SHORTWAVE
TROF APPROACHING FROM THE WEST AS IT ROUNDS THE BASE OF THE LONG
WAVE TROF OVER THE OH/TN VALLEYS. BOTH THE GFS AND NAM SHOW
LINGERING MID LEVEL MOISTURE...SO I EXPECT THIS WAVE WILL AT LEAST
FORCE A FAIR AMOUNT OF MID LEVEL CLOUDINESS OVERNIGHT. TEMPS WILL
RUN A CATEGORY OR TWO ABOVE NORMAL.

WEDNESDAY...ANOTHER POTENT SHORTWAVE WILL DIVE THRU THE LONGWAVE
TROF AXIS...SHARPENING THE TROF AND CLOSING OFF AN UPPER LOW BY END
OF THE DAY OVER THE OHIO VALLEY. A SECONDARY COLD FRONT ASSOCIATED
WITH THIS ENERGY WILL BE KNOCKING ON THE DOOR OF THE NC MTNS BY 00Z
THU. THE FRONT WILL HAVE SOME MOISTURE WITH IT...AND POPS WILL START
TO RAMP UP ALONG THE TN/NC BORDER DURING THE DAY. EAST OF THE
MTNS...MID CLOUDS ARE EXPECTED TO THIN OUT RESULTING IN A PARTLY TO
MOSTLY SUNNY DAY. HOWEVER...THICKNESSES FALL SHARPLY FROM PREVIOUS
DAY...SO TEMPS WILL BE NOTICEABLY COOLER WITH LESS HUMIDITY. HIGHS
WILL BE AT OR SLIGHTLY BELOW NORMAL.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 230 PM EDT TUESDAY...A 500 MB LOW CENTER WILL MOVE SOUTHEAST
OVER THE SOUTHERN APPALACHIANS WED NIGHT THROUGH THU. H5 TEMPS WILL
DIP TO MINUS 25 DEG C OR COLDER UNDER THE LOW CENTER...WITH STEEP
MID LEVEL LAPSE RATES RESULTING THROUGH THE SHORT RANGE PERIOD. MOST
OF THE MOISTURE ASSOCIATED WITH THE UPPER LOW AND REINFORCING
SURFACE COLD FRONT SHOULD BE AT LOW LEVELS...WITH NW UPSLOPE
MOISTURE BEING THE MAIN DRIVER FOR WESTERN MOUNTAIN PRECIPITATION
EARLY THU THROUGH FRI. ALTHOUGH PROFILES GET MARGINALLY COLD ENOUGH
FOR SNOW OR GRAUPEL ALONG THE HIGHEST RIDGES...ESPECIALLY THU
MORNING...A SURFACE BASED WARM LAYER SHOULD KEEP ANY ACCUMULATIONS
AT BAY. WILL ALSO PERMIT LOWER CHANCE PROBABILITIES FOR SHOWERS TO
SPREAD EAST ALONG MAINLY THE INTERSTATE 40 CORRIDOR THROUGH THU
AFTN. THE 500 MB LOW CENTER WILL THEN MEANDER AND VERY SLOWLY FILL
ALONG THE EASTERN SEABOARD THU NIGHT THROUGH FRI...WITH WESTERN
CAROLINA PRECIPITATION CHANCES SLOWLY DIMINISHING.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 240 PM EDT TUESDAY...500 MB HEIGHTS WILL RISE FROM THE WEST ON
SATURDAY AS THE CLOSED UPPER LOW DEPARTS TO THE EAST. DRIER SURFACE
HIGH PRESSURE MOVE INTO PLACE...BUT WITH A SLOWLY APPROACHING BACK
DOOR COLD FRONT OVER THE WEEKEND. BETTER MOISTURE POOLING ALONG THE
COLD FRONT COULD FLIRT WITH THE NORTHERN TIER LATE IN THE
WEEKEND...BUT WITH FAIRLY LOW PRECIPITATION CHANCES. THE BOUNDARY
SHOULD STALL SOMEWHERE IN THE REGION SUNDAY INTO MONDAY...BEFORE
RETURNING NORTH AS A WARM FRONT EARLY NEXT WEEK. DIURNAL ISOLATED TO
SCATTERED MOUNTAIN SHOWERS WILL RETURN AND INCREASE INTO
TUESDAY...ALONG WITH RISING TEMPERATURES.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
AT KCLT...CONVECTION IS FIRING ACROSS THE NC ESCARPMENT AND TRACKING
EAST...WITH THE MAIN TSTM MAKING A BEELINE FOR KCLT. TIMING THE
STORM...EXPECT IT TO BE IN THE VICINITY IN THE 19-21Z TIME FRAME.
OTHER THAN VARIABLE WIND GUSTS ASSOCIATED WITH THE
CONVECTION...WINDS SHOULD FAVOR A SW DIRECTION THRU ABOUT 02Z...WITH
A COLD FRONT SHOULD PASS TO THE EAST. THEN WINDS SWITCH TO NW FOR THE
REST OF THE PERIOD...INCREASING TO 6 KT OR MORE BY MIDDAY WEDNESDAY.
CONDITIONS ARE EXPECTED TO BE VFR OTHER THAN WITH THE TSRA...WITH
LINGERING LOW VFR CIGS OVERNIGHT...SCATTERING OUT AFTER DAYBREAK
WEDNESDAY.

ELSEWHERE...CONVECTION IS FAVORING A SUBTLE BOUNDARY ROUGHLY ALONG
THE NC/SC BORDER...WITH ONLY ISOLATED TO SCATTERED SHRA/TSRA
EXPECTED ELSEWHERE THE REST OF THE AFTN. A COLD FRONT WILL EXIT TO
THE EAST EARLY THIS EVENING...WITH DRYING NWLY FLOW TAKING OVER THE
AREA FOR THE REST OF THE PERIOD. MOISTURE WILL LINGER FOR VFR CIGS
MAINLY IN THE NC FOOTHILLS/PIEDMONT...AND MVFR CIGS WORKING UP THE
VALLEY TO KAVL. THERE MAY BE SOME PATCHY FOG AROUND ANY SITES THAT
RECEIVE SOME RAIN THIS AFTN/EVE THEN SEE WINDS GO LIGHT WITH
CLEARING SKIES. BUT OVERALL...NOT EXPECTING MUCH FOG TONIGHT. CLOUDS
SHOULD SCATTER OUT AFTER DAYBREAK WEDNESDAY...AS DRIER AIR FILTERS
IN FROM THE NW.

OUTLOOK...A STRONG UPPER LOW WILL SWING THRU THE AREA WED NIGHT THRU
FRIDAY...AND WILL BRING SHRA AND TSRA MAINLY ACROSS THE NC SITES
BOTH THU AND FRI AFTN.

CONFIDENCE TABLE...

            19-01Z        01-07Z        07-13Z        13-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     MED   79%     MED   73%     HIGH  96%
KHKY       HIGH  83%     HIGH 100%     HIGH 100%     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 SCHEDULE TAF ISSUANCE FLIGHT RULE CATEGORY.  COMPLET HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK:

WWW.WEATHER.GOV/GSP/AVIATION

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...HG
NEAR TERM...ARK
SHORT TERM...HG
LONG TERM...HG
AVIATION...ARK



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.