Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 011824
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
224 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 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 /19Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...LOWER END VFR CIGS REMAIN IN PLACE IN THE NRLY FLOW THIS
AFTN...WITH UPSTREAM CIGS GENERALLY LIFTING TO LOWER VFR AS WELL.
CAN THUS KEEP BASES AT VFR LEVELS THROUGHOUT GOING FORWARD. ANY
ADDITIONAL SHOWERS SHOULD STAY MAINLY EAST OF INTERSTATE 77...BUT
WILL KEEP A VCSH MENTION GOING THROUGH LATE AFTN FOR ANY ADDITIONAL
MOISTURE ROTATING SWD. NRLY WINDS WITH LOW END GUSTS TO THE UPPER
TEENS OR NEAR 20 KT WILL CONTINUE UNTIL SUNSET...BUT WITH THE PRES
GRADIENT RELAXING OVERNIGHT INTO SATURDAY WITH CONTINUED DRYING.

ELSEWHERE...EXPECT MAINLY SCT TO BKN VFR CLOUDS THROUGH LATE
DAY...WITH SCATTERING THIS EVENING AS PROFILES DRY FROM THE WEST.
LOW END GUSTS WILL CONTINUE AT TIMES...WITH SOME GUSTS TO 25 KT OR
BETTER AT KAVL...UNTIL SUNSET. THE PRES GRADIENT WILL RELAX AS HIGH
PRES BUILDS IN OVERNIGHT. EXPECT JUST A FEW HIGH CLOUDS SAT MORNING
WITH LIGHT NW FLOW THROUGHOUT.

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...

            18-24Z        00-06Z        06-12Z        12-18Z
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
SHORT TERM...WIMBERLEY
LONG TERM...RWH
AVIATION...HG


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