Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 020239
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1039 PM EDT FRI MAY 1 2015

.SYNOPSIS...
DEEP LAYER RIDGING WILL PREVAIL THROUGH MID WEEK. ALTHOUGH DRIER
CONDITIONS ARE EXPECTED...AN OCCASIONAL SHOWER OR THUNDERSTORM WILL
BE POSSIBLE DURING PEAK HEATING FROM SUNDAY THROUGH LATE WEEK...
MAINLY ACROSS THE MOUNTAINS. TEMPERATURES WILL MODERATE TO ABOVE
NORMAL LEVELS.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 1020 PM...SKIES ARE CLEARING ACROSS THE FORECAST AREA THIS
EVENING AS THE BOUNDARY LAYER CONTINUES TO COOL. MTN VALLEYS AND
OUTER PIEDMONT LOCATIONS HAS ALSO SEEN WINDS DECOUPLE...SETTING THE
STAGE FOR A PRETTY GOOD RADIATIONAL COOLING EVENT IN THOSE AREAS
OVERNIGHT...AND WARRANTING ABOUT A CATEGORY REDUCTION IN MIN TEMPS.
SOME OF THE OUTLYING/TYPICAL COOL SPOTS WILL PROBABLY ALSO SEE A
LITTLE FOG DEVELOP SATURDAY MORNING...ESP IN THE VALLEYS OF
SOUTHWEST NC.

AS OF 730 PM...SHOWER BAND THAT DROPPED OUT OF VIRGINIA INTO THE
NORTHERN NC PIEDMONT EARLIER THIS EVENING CONTINUES TO DISSIPATE
ALONG THE I-77 CORRIDOR. THIS SHOULD BE IT IN TERMS OF POPS FOR THE
REMAINDER OF THE TONIGHT PERIOD. OTHERWISE...SKIES SHOULD CONTINUE
TO CLEAR IN MOST AREAS AS CU/STRATOCU DISSIPATE WITH THE LOSS OF
INSOLATION.

AS OF 225 PM EDT...THE UPPER LEVEL CLOSED CIRCULATION HAS MOVED EAST
OVER THE NC OUTER BANKS THIS AFTN. MOISTURE CONTINUES TO ROTATE
SOUTHWARD BEHIND THIS FEATURE INTO WRN NC WHERE LAPSE RATES REMAIN
FAIRLY STEEP ALOFT...HOWEVER BETTER SFC BASED INSTABILITY IS
GENERALLY EAST OF THE FORECAST AREA AND LITTLE ADDITIONAL TRIGGERING
IS ANTICIPATED BACK TO THE WEST. WILL THUS CONFINE ANY LINGERING
LATE DAY SHOWER CHANCES MAINLY TO LOCATIONS EAST OF INTERSTATE 77.
GUSTY WINDS WILL PERSIST UNTIL SUNSET IN THE NRLY FLOW PRES GRADIENT
BEHIND THE COASTAL LOW PRESSURE AND EAST OF THE BUILDING HIGH PRES.
SHALLOW NW FLOW MOISTURE WILL LINGER IN THE WRN MTNS FOR A WHILE
TONIGHT...PRODUCING MAINLY CLOUDS BUT NO ADDITIONAL EVENING SHOWERS.

SFC HIGH PRESSURE WILL GRADUALLY SETTLE OVER THE REGION FROM THE
WEST OVERNIGHT THROUGH SATURDAY AS PROFILES STEADILY DRY OUT AND THE
PRES GRADIENT WEAKENS. THERE IS ONE WEAK SHORTWAVE IN THE NW FLOW
ALOFT THAT WILL CROSS THE SRN APPALACHIANS LATE SAT AFTN. IN
ADDITION...ENOUGH LOW LEVEL CONVERGENCE COULD FORM TO PRODUCE ISOLD
ERN ESCARPMENT SHOWERS CIRCA 21Z...BUT COVERAGE SHOULD REMAIN
MINIMAL GIVEN THE RELATIVELY DRY BOUNDARY LAYER. MAX TEMPS WILL
RECOVER CLOSER TO CLIMO FOR SAT AFTN.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 200 PM FRI...HIGH PRESSURE CENTERED OVER THE SRN APPALACHIANS
SATURDAY NIGHT WILL MOVE OFF THE CAROLINA COAST BY SUNDAY EVENING.
LIGHT SOUTHERLY FLOW SHOULD RETURN ON SUNDAY TO AID LIFT AS WELL AS
WARMING...AND A MINOR SHORTWAVE PASSING OVERHEAD MIGHT PROVIDE A
SLIGHT BOOST AS WELL. HOWEVER MIDLEVEL LAPSE RATES REMAIN MARGINAL
BENEATH A MEAN UPPER RIDGE. LOW POPS OVER THE HIGHER TERRAIN STILL
LOOK APPROPRIATE. THE SHORTWAVE BECOMES STAGNANT OVER THE AREA SUNDAY
NIGHT WHILE THE HIGH REMAINS OFFSHORE. A SLIGHTLY STRONGER LLVL
GRADIENT WILL ALLOW EVEN BETTER WARM/MOIST FLOW...WHILE THE COOLER
AIR IN THE MID-UPPER LEVELS WILL IMPROVE LAPSE RATES. INSTABILITY
WILL BE GREATER ON MONDAY...AS WILL POPS...THOUGH THEY GENERALLY WILL
REMAIN OVER THE NW HALF OF THE CWFA. DEEP SHEAR IS RATHER WEAK BOTH
DAYS...LOW ENOUGH TO MINIMIZE ORGANIZATION OF ANY STORMS THAT DO FORM
AND KEEP SEVERE WX CHANCES MINIMAL. ON THE OTHER HAND IT IS LIKELY
HIGH ENOUGH TO MITIGATE A PULSE THREAT OR HEAVY RAIN THREAT DUE TO
SLOW CELL MOTION. TEMPS WILL BE AROUND NORMAL SUNDAY...AND SLIGHTLY
ABOVE NORMAL ON MONDAY.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 215 PM FRIDAY...AN UPPER RIDGE BUILDS ACROSS THE AREA AND
REMAINS IN PLACE THROUGH THE PERIOD. AN UPPER LOW DEVELOPS OVER THE
BAHAMAS AND MOVES NORTH TOWARD THE CAROLINA COAST LATE IN THE
PERIOD. AT THE SFC...HIGH PRESSURE REMAINS ACROSS THE AREA THRU THE
PERIOD KEEPING A BACK DOOR COLD FRONT FROM MOVING SOUTH INTO THE
AREA EARLY IN THE PERIOD...WHILE A HYBRID LOW DEVELOPS OVER THE
BAHAMAS AND APPROACHES THE CAROLINA COAST BY THE END OF THE PERIOD.
THE GUIDANCE DOES DIFFER IN THE TRACK OF THE LOW WITH THE 01/00Z
ECMWF SHOWING IT MAKING LANDFALL NEAR CAPE LOOKOUT...WHILE THE GFS
KEEPS IT OFF SHORE THROUGHOUT. EITHER WAY...THERE WILL BE LITTLE
EFFECT FROM THIS SYSTEM ON THE SENSIBLE WX ACROSS OUR CWFA. THE MAIN
WEATHER FEATURE WILL BE THE DIURNAL ISOLATED TO SCT CONVECTION EACH
DAY MAINLY ACROSS THE MTNS. CONVECTIVE CHC DOES INCREASE LATE IN THE
PERIOD OUTSIDE OF THE MTNS AS INSTABILITY...THOUGH WEAK...DOES BUILD
EACH DAY AND MID LEVEL SUBSIDENCE INVERSION DIMINISHES. TEMPS START
OUT A LITTLE ABOVE NORMAL AND RISE A FEW DEGREES THRU THE PERIOD.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS EXPECTED THROUGH THE
PERIOD...ALONG WITH GENERALLY DIMINISHING/LIGHT N OR NW WINDS. CLOUDS
WILL BE LIMITED TO FEW/SCT CU/STRATOCU EARLY IN THE PERIOD...WHICH
SHOULD DISSIPATE IN MOST AREAS BY LATE EVENING. SOME FOG/PSSBL LOW
STRATUS COULD DEVELOP IN THE MTN VALLEYS SOUTHWEST OF KAVL TOWARD
DAYBREAK...BUT AGAIN THE MAIN TAF SITES SHOULD REMAIN VFR.

OUTLOOK...MAINLY DRY CONDITIONS WILL PERSIST THROUGH THE PERIOD...
BUT WITH RETURN FLOW MOISTURE VERY SLOWLY REDEVELOPING OVER THE MTNS
THROUGH EARLY NEXT WEEK.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-00Z
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 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 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...RWH
NEAR TERM...HG/JDL
SHORT TERM...WIMBERLEY
LONG TERM...RWH
AVIATION...JDL


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