Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 040022
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
822 PM EDT SUN MAY 3 2015

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN ACROSS THE REGION THROUGH THE MIDDLE OF
THE WORK WEEK. ISOLATED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
EACH AFTERNOON OVER THE MOUNTAINS...WITH CHANCES IMPROVING ACROSS
THE PIEDMONT THURSDAY WHEN A WEAK COLD FRONT MOVES IN FROM THE
NORTH. TEMPERATURES WILL RISE TO ABOVE NORMAL LEVELS...WITH HIGHS
TOPPING OUT IN THE LOWER TO MID 80S THE LATTER HALF OF THE WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
0015 UTC UPDATE...POPS AND QPF WERE INCREASED SLIGHTLY ALONG THE TN
BORDER WHERE SOME VERY LIGHT RADAR RETURNS WERE NOTED.

AS OF 230 PM EDT...AN UPPER LEVEL SHORTWAVE MOVING EAST OF THE OH
VALLEY LATE THIS AFTERNOON HAS SPAWNED SCATTERED SHOWERS BACK ACROSS
KY. THIS WAVE WILL MOVE THROUGH THE CENTRAL/SRN APPALACHIANS LATE
THIS AFTN...WITH THE BEST DPVA CROSSING THE NRN HALF OF THE FORECAST
AREA THROUGH 22Z. A 500 MB COLD POCKET IN THE UPPER THERMAL TROUGH
WILL CROSS THE NRN TIER OVERNIGHT...WHICH COULD KEEP ISOLD SHOWERS
GOING ALONG THE INTERSTATE 40 CORRIDOR WHERE LAPSE RATES WILL BE
STEEPEST. WILL FEATURE MAINLY MTN ISOLD TO SCT POPS FOR LATE
AFTN...THEN PUSH ISOLD SHOWER POPS EAST INTO THE WRN NC PIEDMONT
INTO THE EARLY MORNING HOURS. INSTABILITY REMAINS WEAK...AND SOME
MEASURE OF CAPPING IS FOUND IN RAOB AND MODEL PROFILES AT 10 TO 12
KFT...SO WILL ONLY MENTION SHOWERS FOR NOW. EXPECT A SCATTERED TO
BKN MID DECK OF CLOUDS TO PERSIST OVERNIGHT UNDER THE WEAK CAPPING
LAYER...WITH WARMER MIN TEMPS MAINLY IN THE 50S/HIGH MTN UPPER 40S.

THE CENTER OF THE SE SFC HIGH PRESSURE WILL MOVE FARTHER OFFSHORE
OVERNIGHT THROUGH MONDAY...WITH BERMUDA HIGH PRESSURE DOMINATING THE
REGION. MODEL PROFILES EXHIBIT LESS CAPPING ALOFT ON MONDAY
AFTN...AND LIGHT SRLY UPSLOPE FLOW SHOULD PERSIST AROUND THE
ATLANTIC RIDGE. WILL THUS FEATURE SLIGHTLY BETTER SCATTERED MOUNTAIN
COVERAGE FOR MONDAY AFTERNOON. MAX TEMPS WILL RECOVER ANOTHER COUPLE
OF DEGREES ABOVE SUNDAY VALUES IN MOST AREAS.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 200 PM SUNDAY...BERMUDA HIGH AND SERN CONUS UPPER RIDGE WILL
REMAIN DOMINANT DURING THE MIDDLE OF THE WEEK. DIURNALLY DRIVEN
SHRA/TSRA WILL RETURN TUESDAY AND WEDNESDAY MAINLY OVER THE HIGHER
TERRAIN. THE RIDGE APPEARS TO REACH A PEAK ON TUESDAY BEFORE COMING
UNDER THE INFLUENCE OF A BACKDOOR COLD FRONT SINKING THRU THE
MID-ATLANTIC TO OUR NORTH...AND DEVELOPING LOW PRESSURE NEAR THE
BAHAMAS. LOW LEVEL FLOW TURNS MORE TOWARD E OR NE FOR WED. THOUGH
THIS APPEARS TO HAVE LITTLE IMPACT ON DEWPOINTS OR INSTABILITY...IT
MAY MEAN THE FOCUS OF CONVECTION SHIFTS FROM SRN FACING SLOPES TO ERN
FACING ONES. THICKNESSES TICK UPWARD FROM TUE TO WED AND MODEL MAX
TEMPS FOLLOW. SHEAR REMAINS QUITE WEAK AND CELLS WILL BE
SLOW-MOVING...BEING CAPABLE OF LOCALLY HEAVY RAIN PARTICULARLY ON
TUESDAY. FOR WED THE UPPER LEVELS WILL HAVE DRIED OUT QUITE A BIT AS
DRIER AIR IS WRAPPED AROUND THE HIGH...REDUCING THE LIKELIHOOD OF
HEAVY RAINFALL BUT ENHANCING DOWNBURST POTENTIAL. SEVERE CHANCES ARE
NONZERO BUT LOOK LOW ENOUGH NOT TO MENTION IN THE HWO AT THIS
ISSUANCE...MAINLY IN LIGHT OF THE MODEST INSTABILITY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 200 PM SUNDAY...BACKDOOR COLD FRONT MOVES SWD INTO NC ON
THURSDAY AS LOW PRESSURE SPINS OVER THE ATLANTIC BETWEEN THE OUTER
BANKS AND THE BAHAMAS. EASTERLY FLOW INTO THE CWFA IS MAINTAINED INTO
FRI MAINLY BY HIGH PRESSURE ON THE N SIDE OF THE BOUNDARY. MODEL
DIFFERENCES ARE RATHER SIGNIFICANT BEYOND THAT. 03/12Z GFS IS
CONSISTENT WITH THE PREVIOUS COUPLE RUNS IN TAKING THE LOW INTO THE
GA COAST...WHILE THE 03/00Z EC AND GEM TRACK IT TO THE CAPE FEAR AREA
INSTEAD. GFS MORE CLEARLY SHOWS AN INTERACTION BETWEEN THE FRONT AND
THE LOW NEAR THE NC/SC COAST. IT DEPICTS THE HIGH REMAINING IN
CONTROL FRI WITH RELATIVELY STABLE AIR IN PLACE...BEFORE THE LOW
MOVES WWD AND INITIATES WARM ADVECTION INTO THE WRN CAROLINAS BY SAT
MRNG. THE MORE ERN TRACK DEPICTED ON THE EC/GEM SOLUTIONS BRINGS
LITTLE TO NO LOW LEVEL FORCING INTO THE AREA. GIVEN THE MODEL
DIFFERENCES AS WELL AS THE MID-UPPER RIDGE REMAINING STRONG OVER THE
REGION...SENSIBLE WX EFFECTS FROM THE COASTAL LOW MAY BE LIMITED THIS
FAR INLAND. CONFIDENCE IS BELOW AVERAGE...BUT FOR NOW IT APPEARS POPS
WILL CONTINUE TO REFLECT A NOTABLE DIURNAL SIGNAL. CLOUD COVER WILL
BE A BIT MORE THAN OTHERWISE WOULD BE EXPECTED BENEATH A RIDGE. TEMPS
WILL BE A COUPLE CATEGORIES ABOVE CLIMO.

&&

.AVIATION /01Z MONDAY THROUGH FRIDAY/...
AT KCLT...VFR. A LOW VFR CIG IS POSSIBLE UNDER A WEAK INVERSIONS
OVERNIGHT...ERODING WITH MIXING AND HEATING AFTER DAYBREAK. THE
LOWER LEVELS APPEAR TOO DRY FOR DAYBREAK FOG. LIGHT SURFACE WINDS
WILL FAVOR THE S TONIGHT...AND SSW ON MONDAY.

ELSEWHERE...VFR. LOW VFR CIGS ARE POSSIBLE OVERNIGHT IN NC AS A WEAK
INVERSIONS SETS UP ALOFT. HEATING AND MIXING SHOULD CAUSE THE CIGS
TO ERODE AFTER DAWN. LOW VFR CIGS RETURN TO KAVL AND KHKY IN THE
AFTERNOON WITH MOIST UPSLOPE FLOW. LAMP GUIDANCE FAVORS LOW VFR VSBY
AT KAVL AROUND DAYBREAK...WITH MORE DIRE CONDITIONS IN THE NC
FOOTHILLS AND SW MOUNTAIN VALLEYS. WITH MODEL SOUNDING PROFILES
APPEARING RATHER DRY...A MODEL CONSENSUS OF VFR WILL BE FAVORED.
LIGHT S WINDS WILL VEER SW OVERNIGHT.

OUTLOOK...ISOLATED TO SCATTERED DIURNAL CONVECTION IS EXPECTED
THROUGH THURSDAY...MAINLY OVER THE MTNS...AS MOIST SOUTHERLY FLOW
PERSISTS.

CONFIDENCE TABLE...

            00-06Z        06-12Z        12-18Z        18-00Z
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...SBK
NEAR TERM...HG/JAT
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...JAT



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