Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 242050
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
450 PM EDT SUN MAY 24 2015

.SYNOPSIS...
DRY CANADIAN HIGH PRESSURE WILL REMAIN OVER THE REGION TONIGHT. AS
THE HIGH SLIDES FARTHER EASTWARD...IT TAKES ON A SUMMERTIME BERMUDA
PATTERN FOR MEMORIAL DAY AND REMAINS THERE THROUGH THE WEEK. THIS
PRODUCES A MOIST SOUTHERLY FLOW WITH INCREASED CHANCES FOR
WIDESPREAD CONVECTION EACH DAY AND EVENING.

&&

.NEAR TERM /THROUGH MONDAY/...
415 PM UPDATE...TOUCHED UP SKY COVER INTO THIS EVENING...SLOWING THE
ARRIVAL OF CLOUDIER SKIES A BIT PER 18Z NAM. ALSO MADE MINOR
ADJUSTMENTS TO T/TD...BUT OVERALL THE FCST LOOKS GOOD.

AS OF 220 PM EDT SUNDAY...ANOTHER PLEASANT EVENING IN STORE FOR
NORTHEAST GA AND THE WESTERN CAROLINAS AS DEEP LAYER RIDGING
PREVAILS.  TEMPERATURES ACROSS THE REGION THIS AFTERNOON HAVE WARMED
INTO THE MID/UPPER 70S WITH A FEW LOWER PIEDMONT SITES BREAKING INTO
THE LOWER 80S.  SKIES REMAIN PARTLY CLOUDY ACROSS LOW TERRAIN WITH
MOSTLY SUNNY SKIES PREVAILING OVER THE MTNS THROUGH THE AFTERNOON.
SOUTHEAST FLOW AROUND THE PARENT SURFACE HIGH OFF THE MID ATLANTIC
COAST WILL CONTINUE THROUGH THE PERIOD ALL THE WHILE ADVECTING IN
ATLANTIC MOISTURE.  THUS...MODELS FAVOR INCREASING CLOUDINESS OVER
THE REGION BY MORNING MONDAY...WITH MOSTLY CLOUDY SKIES PREVAILING
ON THE WESTERN PERIPHERY OF THE HIGH OVER NORTHEAST GA...SOUTHWEST
NC...AND THE WESTERN UPSTATE OF SC.  THE FCST REMAINS DRY THROUGH
MID MORNING BEFORE FLOW VEERS FURTHER SOUTH AND INCREASES...THEREBY
ALLOWING FOR BETTER UPSLOPE POTENTIAL ACROSS THE UPPER FRENCH BROAD
REGION.  IN RESPONSE...SLIGHT CHANCE POPS WILL INCREASE AROUND THE
15Z TIMEFRAME OVER THESE AREAS...BEFORE INCREASING/SPREADING FURTHER
EAST INTO THE NC FOOTHILLS AND CENTRAL UPSTATE FOR THE AFTERNOON AS
MOISTURE IMPROVES AND HEATING STEEPENS LAPSE RATES.  WITH
THAT...SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE WITH LITTLE
ORGANIZATION EXPECTED TO SUPPORT STRONG/SEVERE CONVECTION.
TEMPERATURES THROUGH THE PERIOD WILL GRADUALLY MODERATE WITH HIGHS
ON MONDAY RETURNING TO NEAR NORMAL AMONGST INCREASED HUMIDITY
LEVELS.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 215 PM SUNDAY...WHAT APPEARED A FEW DAYS AGO AS A SIMPLE
DIURNAL CONVECTIVE PERIOD FOR TUESDAY AND WEDNESDAY LOOKS A BIT MORE
COMPLICATED NOW. THE UPPER PATTERN SHOULD EVOLVE SLOWLY WITH AN
UPPER RIDGE/ANTICYCLONE OFF THE SOUTHEAST COAST ELONGATING AND
BECOMING POSITIVELY TILTED...THUS MAINTAINING A MOIST SW FLOW ALOFT
THAT WILL TRANSPORT MOISTURE FROM THE GULF TO THE WRN CAROLINAS.
THERE IS A SUBTLE TREND IN THE GFS THAT SHOWS THE RIDGE AXIS A BIT
FARTHER OFFSHORE...WHICH ESSENTIALLY WOULD MEAN THAT THE EASTERN
EXTENT OF THE DEEP CONVECTION WOULD BE TO THE EAST OF THE FCST AREA.
THE COMPLICATION COMES ABOUT BECAUSE OF JET STREAKS LIFTING NWD OUT
OF THE UPPER TROF AND WEAK CONVECTIVELY INDUCED VORT CENTERS THAT
MOVE UP FROM THE SW THRU THE PERIOD. THE PASSAGE OF THESE FEATURES
IS DIFFICULT TO PIN DOWN...HOWEVER...THE PATTERN ALSO FAVORS A WEAK
MOIST ATLANTIC UPSLOPE FLOW AT LOW LEVELS. THIS MEANS THAT EVEN
THOUGH THERE WILL BE SOME ENHANCEMENT OF PRECIP CHANCES DURING PEAK
HEATING...THE CHANCE OF SHOWERS AND STORMS WILL PROBABLY NEVER
REALLY GO AWAY EITHER TUESDAY NIGHT OR WEDNESDAY NIGHT. PRECIP
CHANCES WERE NUDGED UPWARD A BIT THRU THE PERIOD...AS WAS SKY
COVER...AND THAT SHOULD SERVE TO KEEP TEMPS A FEW DEGREES COOLER
THAN PREVIOUSLY THOUGHT. PERHAPS THE COVERAGE OF SHOWERS AND STORMS
WILL BE NUMEROUS ENOUGH THAT IT WILL NOT FEEL SO SUMMER-LIKE AFTER
ALL.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 2 PM EDT SUNDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
THURSDAY WITH MULTIPLE UPPER SHORTWAVES MOVING ACROSS THE GREAT
LAKES AND JUST TO OUR NORTH AS THE UPPER RIDGE AXIS SLIDES OFF THE
EAST COAST. SIMLUTANEOULSY A CLOSED UPPER LOW DEVELOPS WELL OFFSHORE
HOWEVER...COMPARED TO PREVIOUS MODEL RUNS...THE LOW APPEARS TO
REMAIN FARTHER OFFSHORE AND BECOME WEAKER TOWARDS THE END OF THE
MEDIUM RANGE. IN THE MEANTIME...THE OVERALL SYNOPTIC PATTERN DOES
NOT CHANGE SIG FOR THE REMAINDER OF THE PERIOD WITH BROAD RIDGING
PERSISTING OVER THE AREA AND TO OUR EAST.

AT THE SFC...WE WILL BE UNDER THE INFLUENCE OF THE SUMMERTIME
BERMUDA HIGH THRU MOST OF THE PERIOD. THIS WILL KEEP MOIST SLY LOW
LVL FLOW OVER THE REGION WITH THE GOOD CHANCE OF WIDESPREAD
CONVECTION EACH DAY/EVENING. SOME MINOR LOW TO MID LVL DRYING IS
POSSIBLE ON FRI AND SAT...YET ITS LOOKING LESS SUBSTANTIAL COMPARED
TO PREVIOUS MODEL GUIDANCE. THE MODELS GENERATE AN ELONGATED COLD
FRONT TO OUR NW ON SAT. THIS FRONT IS ASSOCIATED WITH A SFC LOW THAT
DEEPENS AS IT MOVES WELL NE OF THE GREAT LAKES. THE FRONTAL ZONE IS
SLOW TO REACH THE CWFA AND COULD ESSENTIALLY JUST LAY ACROSS THE
NORTHERN FRINGE OF THE FCST AREA BY THE VERY END OF THE PERIOD LATE
SUN. AS FOR THE SENSIBLE FCST...WE CAN EXPECT A TYPICAL WARM
SUMMERTIME PATTERN WITH GOOD CHANCES FOR WIDESPREAD SHOWERS AND TS
EACH DAY WITH SOMEWHAT REDUCED CHANCES ON FRI AND SAT OVER THE
SOUTHEASTERN ZONES AS PROFILES SHOULD BE DRIER OVERALL...BUT WITH
GOOD AMOUNTS OF INSTABILITY STILL PRESENT.

&&

.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
AT KCLT...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD.  TAF
INITIALIZES WITH LIGHT/MODERATE SOUTHEAST FLOW BENEATH LOW VFR CU
FIELD AND HIGH LEVEL BKN CIGS.  EXPECTING THIS TO PREVAIL THROUGH
THE AFTERNOON INTO EARLY EVENING BEFORE LOW CLOUDS ERODE AFTER
SUNSET.  AS SOUTHEASTERLY FLOW CONTINUES THROUGH THE
OVERNIGHT...MOISTURE WILL ADVECT NORTH FROM THE ATLANTIC AROUND THE
WESTERN PERIPHERY OF THE OFFSHORE MID ATLANTIC RIDGE.  THUS...SKY
COVER WILL INCREASE AROUND DAYBREAK WITH MID CLOUDS SPREADING IN
AHEAD OF LOW VFR.  MVFR CIGS WILL LIKELY BE JUST TO THE
WEST...THEREFORE FURTHER CIG DETERIORATION IS POSSIBLE IN LATER TAF
ISSUANCE.  WINDS WILL REMAIN OUT OF THE SOUTH/SOUTHEAST DURING THIS
TIMEFRAME.

ELSEWHERE...MUCH THE SAME AS KCLT ABOVE WITH SOUTHERLY FLOW
PREVAILING UNDER LOW VFR CU AND HIGH LEVEL CIRRUS THIS AFTERNOON.
CIGS WILL BUILD IN FROM THE SOUTHWEST OVERNIGHT AS MOISTURE
ADVECTION AROUND THE ABOVE MENTIONED HIGH INTRUDES.  THUS...CARRIED
MVFR CIGS AT ALL SC SITES AND KAVL BY MID/LATE MORNING WITH A PERIOD
OF IFR AT KAND.  NO RESTRICTIONS EXPECTED AT KHKY.  ALL RESTRICTIONS
WILL IMPROVE AFTER SUNSET ATOP OF INCREASING SOUTHERLY FLOW.
SHRA/TSRA CHANCES WILL ALSO INCREASE TOMORROW OVER THE
WEST...HOWEVER CONFIDENCE REMAINS LOW ENOUGH TO LEAVE OUT OF TAF.

OUTLOOK...MOISTURE WILL GRADUALLY RETURN OUT OF THE SOUTH THRU THE
MIDDLE OF THE WEEK. SO INCREASED MORNING STRATUS...AND A RETURN OF
ISOLD TO SCATTERED AFTN/EVE SHRA/TSRA CAN BE EXPECTED BY TUESDAY-
WEDNESDAY.

CONFIDENCE TABLE...

            21-03Z        03-09Z        09-15Z        15-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  97%
KGSP       HIGH 100%     HIGH 100%     HIGH  84%     HIGH  92%
KAVL       HIGH 100%     HIGH 100%     HIGH  90%     MED   72%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  95%
KGMU       HIGH 100%     HIGH 100%     HIGH  90%     HIGH  97%
KAND       HIGH 100%     HIGH 100%     MED   60%     HIGH  97%

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...JPT
NEAR TERM...CDG/WIMBERLEY
SHORT TERM...PM
LONG TERM...JPT
AVIATION...CDG



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