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
000
FXUS62 KGSP 211140
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
740 AM EDT THU MAY 21 2015

.SYNOPSIS...
UNSETTLED WEATHER WILL CROSS THE AREA TODAY AS A COLD FRONT SLOWLY
PUSHES SOUTH AND EAST. DRIER CANADIAN HIGH PRESSURE WILL BUILD OVER
THE CAROLINAS AND NORTHEAST GEORGIA FRIDAY AND REMAIN THROUGH THE
WEEKEND. SOUTHERLY FLOW MOISTURE AROUND BERMUDA HIGH PRESSURE WILL
GRADUALLY RETURN EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM THU...LOW PRESSURE IS CURRENTLY CENTERED OVER THE
SRN APPALACHIANS...MOVING SLOWLY EWD ALONG A STALLED FRONTAL
BOUNDARY. THE BOUNDARY MARKS THE LEADING EDGE OF A DRY CONTINENTAL
AIRMASS SPRAWLING WEST OF THE MTNS. MUCH COOLER/DRIER AIR HAS
ALREADY WORKED THRU MOST OF TENNESSEE. AS MOISTURE INCREASES ON
STRENGTHENING UPSLOPE FLOW BEHIND THE LOW...THE GOING SHOWER
ACTIVITY OVER EAST TN WILL CONTINUE TO PUSH INTO WRN NC FOR A
COUPLE MORE HRS AT LEAST. THOUGH MOST OF THE PIEDMONT ZONES REMAIN
IN THE WARM SECTOR OF THE LOW...IT LOOKS LIKE THE ADVECTION OF
MORE UNSTABLE AIR HAS CEASED. CAN/T RULE OUT SOME LIGHT CONGESTED
SHOWERS THIS MRNG...BUT THUNDER IS LOOKING LESS LIKELY.

THE LOW WILL SLOWLY DEPART THE AREA OVER THE COURSE OF THE DAY...BUT
POPS WILL DIMINISH EAST OF THE MTNS. SUFFICIENT MOISTURE REMAINS
THERE ON THE UPSLOPE FLOW TO KEEP A POP THRU THIS EVENING. EAST OF
THE MTNS DOWNSLOPING AND DRYING IMPLIES CLEARING SKIES. MAX TEMPS
WILL BE MUCH COOLER IN THE MTNS...REACHING ONLY THE MID 70S IN THE
VALLEYS. THE PIEDMONT WILL REMAIN ABOVE NORMAL...MOSTLY MID
80S...BUT WITH LOWER HUMIDITY. A RATHER TIGHT PRESSURE GRADIENT
REMAINS ACRS THE CWFA INTO TONIGHT. THE ORIENTATION OF THE GRADIENT
AS WELL AS A SUBSIDENCE INVERSION NEAR THE TOP OF THE MTNS SUGGESTS
THAT A GAP WIND MAY HOWL IN MTN VALLEYS...PARTICULARLY THE FRENCH
BROAD...KEEPING ASHEVILLE GUSTY MUCH OF THE NIGHT TONIGHT. THIS
COULD ALSO BRING SOME BRISK GUSTS TO GREENVILLE AND SPARTANBURG AS
WELL. MINS WILL BE SLIGHTLY BELOW NORMAL.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
AS OF 245 AM EDT THU...A PROMINENT RIDGE AXIS OVER THE CENTRAL CONUS
ON FRIDAY WILL STEADILY MIGRATE EASTWARD AND BUILD OVER THE ERN
SEABOARD THROUGH THE WEEKEND. A SPRAWLING SFC HIGH CENTER WILL MOVE
OVER THE REGION UNDER THE RIDGE...WITH LOWER THICKNESSES ACROSS THE
REGION ON FRIDAY AND AGAIN ON SATURDAY WITH THE ARRIVAL OF A WEAKLY
REINFORCING BACK DOOR COLD FRONT. EXPECT NEAR CLIMO MINS BUT WITH
MAXES A COMFORTABLE CATEGORY OR SO BELOW CLIMO IN MOST AREAS FRI AND
SAT AFTERNOON.

THE SFC HIGH WILL MOVE OFF THE COAST ON SUNDAY...WITH A MODERATING
SRLY FLOW DEVELOPING INTO THE FORECAST AREA. MAX TEMPS WILL CLIMB
BACK TO NEAR OR SLIGHTLY ABOVE NORMAL. WEAK SE TO S UPSLOPE FLOW
COULD PRODUCE ISOLD SHRA IN THE EXTREME SRN MTNS...BUT CHANCES
APPEAR TOO SMALL TO INCLUDE FOR MOST LOCATIONS AT PRESENT.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
AS OF 245 AM EDT THU...THE RIDGE AXIS WILL MIGRATE FURTHER OFFSHORE
EARLY NEXT WEEK...WITH SRLY RETURN FLOW MOISTURE IMPROVING MONDAY
INTO TUESDAY. ANTICIPATE ISOLATED DIURNAL CONVECTIVE CHANCES
INCREASING OVER THE MTNS ON MON AFTN IN UPSLOPE AND WEAK
INSTABILITY. A SLOW AND STEADY UPTICK IN DEWPOINTS...MOISTURE...AND
INSTABILITY WILL OCCUR THROUGH TUE...WITH SCATTERED LATE DAY
SHRA/TSRA COVERAGE POSSIBLE IN THE MOUNTAINS. TEMPERATURES WILL
CONTINUE TO WARM...WITH PIEDMONT MAXES AROUND 90 IN ERN/SE SECTIONS
TUE AFTN.

A SHORTWAVE LIFTING E FROM THE PLAINS WILL SLOWLY START TO BREAK
DOWN THE RIDGE ON WED. THIS WILL ALLOW DEEPER MOISTURE TO MOVE INTO
THE SRN APPALACHIANS AND INCREASE CONVECTION TO MORE SOLID CHANCES.
VERY WARM CONDITIONS WILL CONTINUE THROUGH MID WEEK...WITH MAXES
AROUND 90 IN MANY AREAS EAST OF THE MTNS.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AT KCLT...WEAK LOW PRESSURE WILL SLOWLY MOVE THRU THE AREA THIS
MORNING. THE LOW FORMED ALONG A STALLED BOUNDARY...NOTABLE MAINLY
BECAUSE OF THE MUCH DRIER AIR ON ITS NORTH SIDE. THE LOW HAS
ADVECTED ENOUGH MOISTURE INTO THE PIEDMONT N OF CLT THAT SOME LOW
CIGS ARE PRESENT THERE. GUIDANCE HAS HINTED AT RESTRICTIVE CIGS AT
KCLT ON SOME PAST RUNS BUT CONSENSUS IS NOW VFR. AS THE LOW PASSES
IT WILL TURN THE FLOW AROUND AND ADVECT ANY LOW CLOUDS OUT. IT WILL
BE A CLOSE CALL. A TEMPO IS INCLUDED FOR SHRA AND ALSO FOR WINDS
POTENTIALLY BACKING TO SW AS MIXING GETS UNDERWAY. BY LATE MRNG
SHOWER CHANCES WILL DIMINISH AND WINDS WILL RETURN SOLIDLY NW AS THE
LOW DEPARTS...USHERING IN COLD ADVECTION WHICH WILL GRADUALLY CLEAR
SKIES. WINDS WILL STRENGTHEN AS THE DAY GOES ON...AND GUSTS ARE
LIKELY TO PICK UP AND CONTINUE OVERNIGHT.

ELSEWHERE...VEERING FLOW IS EXPECTED IN THE WAKE OF THE DEPARTING
LOW...AND E OF THE MTNS DIMINISHING PRECIP CHANCES AND SKY COVER ARE
ANTICIPATED. FAIRLY ROBUST PRESSURE GRADIENT WILL REMAIN AS HIGH
PRESSURE MOVES IN FROM THE MID MISSISSIPPI VALLEY LATER TODAY. NWLY
COLD ADVECTIVE FLOW WILL STILL HAVE ENOUGH MOISTURE THAT SOME LOW
PRECIP CHANCES AND MVFR LEVEL CLOUD COVER WILL LINGER ON THE WRN
SLOPES OF THE NC MTNS...POSSIBLY DRIFTING OVER KAVL. NW WINDS AND
GUSTS WILL PICK UP AND PERSIST OVERNIGHT. SETUP APPEARS FAVORABLE
FOR A GAP WIND TO KEEP KAVL/KGSP/KGMU REMARKABLY GUSTY MUCH OF
TONIGHT.

OUTLOOK...DEEP HIGH PRESSURE WILL SETTLE OVER THE SOUTHEAST LATE
THIS WEEK AND REMAIN THROUGH TUESDAY. CONDITIONS SHOULD REMAIN
GENERALLY FAIR THROUGH THE PERIOD.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-06Z
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...WIMBERLEY
NEAR TERM...WIMBERLEY
SHORT TERM...HG
LONG TERM...HG
AVIATION...WIMBERLEY


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