Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 281738
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
138 PM EDT SUN JUN 28 2015

.SYNOPSIS...
A COLD FRONT WILL PUSH OUT OF THE REGION EARLY TODAY BRINGING COOLER
AND DRIER CONDITIONS TO START THE NEW WEEK. ANOTHER FRONT WILL
APPROACH THE REGION BY MID-WEEK AND WEAKEN ACROSS THE MOUNTAINS.
THEREAFTER THE REGION WILL STAY IN A WARM AND MOIST ENVIRONMENT
WHICH WILL SUPPORT ISOLATED TO SCATTERED SHOWER AND THUNDERSTORM
COVERAGE TYPICAL OF EARLY JULY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 115 PM...LATEST FOOTHILL AND PIEDMONT OBSERVATIONS INDICATED
THAT TEMPERATURES HAVE RISEN TO AROUND 80 DEGREES WITH 30 DEGREE
DEWPOINT DEPRESSIONS. LATEST SATELLITE IMAGES SHOWED ONLY A FEW CU
ACROSS THE LAKELANDS AND NEAR THE TN BORDER. I WILL UPDATE THE
FORECAST TO ADJUST HOURLY TEMPERATURES AND DEWPOINTS TO OBSERVATIONS
AND DECREASE SKY AND POP.

AS OF 840 AM...IMPRESSIVELY...OBSERVATIONS INDICATED THAT
TEMPERATURES ACROSS PORTIONS OF THE NORTHERN MOUNTAINS HAVE REACHED
THE LOW TO MID 40S THIS MORNING. HOWEVER...MOST AREAS AT
SUNRISE...FROM THE LOWER MTNS VALLEYS TO PIEDMONT...RANGED IN THE
LOW TO MID 60S. I WILL UPDATE THE FORECAST TO ADJUST TEMPERATURES TO
OBSERVATIONS AND ADJUST TO RECENT SATELLITE IMAGES. OTHERWISE...THE
CURRENT FORECAST APPEARS IN GREAT SHAPE.

PREVIOUS DISCUSSION... POST-FRONTAL DEEP LAYERED DRYING WILL
CONTINUE TO OVERSPREAD THE REGION TODAY RESULTING IN A SUNNY SUNDAY.
COMBINED WITH UNSEASONABLY LOW SFC DWPTS...MAXIMUM TEMPERATURES WILL
TOP OUT ABOUT A CATEGORY BELOW CLIMO FOR THE FIRST TIME IN ABOUT TWO
WEEKS. DRY AIR THROUGH A DEEP LAYER LINGERS THROUGH TONIGHT
PROVIDING CLEAR SKIES. WITH THE LINGERING DRY AIR...MONDAY MORNING
MINIMUM TEMPS WILL RADIATE DOWN TO VALUES 6-8 DEG F BELOW NORMAL.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
AT 230 PM EDT SUNDAY...
MAIN LONGWAVE FEATURE IS THE EASTERN US 500MB TROUGH...WHICH MAKES A
SMALL AMOUNT OF EASTWARD PROGRESS TUESDAY AND WEDNESDAY.  SURFACE
TROUGH RUNNING NEAR THE APPALACHIANS WILL MAINTAIN GENERALLY
SOUTHWESTERLY FLOW OVER THE AREA.  THIS REGIME PROVIDES LITTLE
MOISTURE ADVECTION...HOWEVER...DEWPOINTS BEGIN TO RECOVER TUESDAY
MORNING THROUGH EVAPOTRANSPIRATION AND SOME CHANCE FOR PRECIPITATION
AND THUNDER SHOWERS WILL RETURN FOR TUESDAY AND WEDNESDAY
AFTERNOONS.  WESTERLY TO SOUTHWESTERLY FLOW ALOFT OF UP TO 40KTS
WILL PROVIDE SOME EFFECTIVE DEEP LAYER SHEAR...THOUGH WITH LITTLE
DIRECTIONAL SHEAR DOWN TO THE SURFACE.  LI RETURNS TO UNSTABLE
TERRITORY TUESDAY EVENING...AT AROUND -2...OVER THE BLUE RIDGE
MOUNTAINS...AND OVER ALL PARTS OF THE CWA LATE ON WEDNESDAY WITH LI
TO -5.  PRESENCE OF LONGWAVE TROUGH JUST WEST OF THE AREA WITH SOME
BITS OF MILD PVA WILL SUPPORT STORMS.  THIS LEADS TO THE SLIGHT
CHANCE FOR THUNDERSTORMS OVER THE HIGHER TERRAIN TUESDAY
AFTERNOON...AND A BETTER CHANCE OF MORE WIDESPREAD ACTIVITY
WEDNESDAY AFTERNOON.  ISOLATED SEVERE IS NOT OUT OF THE QUESTION ON
WEDNESDAY.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AT 230 AM EDT SUNDAY...ON WEDNESDAY A HIGH AMPLITUDE ANOMALOUS UPPER
TROUGH WILL EXTEND FROM THE CANADIAN ARCTIC TO SOUTHERN GA...WHILE A
SOMEWHAT FLAT UPPER RIDGE RESIDES OVER THE SW USA. THE UPPER RIDGE
RETROGRESSES SLIGHTLY BY THURSDAY...INCREASING THE WAVELENGTH AND
DECREASING THE AMPLITUDE OF THE UPPER PATTERN. ON FRIDAY SHORTWAVE
ENERGY DROPPING INTO THE TROUGH RESULTS IN SLIGHT RETROGRESSION AND
AN INCREASE IN AMPLITUDE. DEAMPLIFICATION IS SEEN AGAIN ON SATURDAY
AS THE SOUTHERN AND NORTHERN STREAM GO OUT OF PHASE...PARTICULARLY
IN WESTERN CANADA.

AT THE SURFACE...WEDNESDAY FEATURES WEAK SURFACE RIDGING OVER THE
SOUTHERN APPALACHIANS...WITH A LEE TROUGH...APPARENTLY THE REMAINS
OF PASSING FRONT...IS DOWNSTREAM OVER THE PIEDMONT. A COLD FRONT
MOVING INTO THE OH RIVER VALLEY ON WEDNESDAY STALLS ON THURSDAY FROM
THE DELMARVA REGION TO THE MID MS RIVER VALLEY. THIS FRONT STARTS TO
MOVE N ON FRIDAY...WHILE A COLD FRONT MOVES ACROSS THE CENTRAL
PLAINS AND MID MS RIVER VALLEY. THIS FRONT WEAKENS AS IT CROSSES THE
SOUTHERN APPALACHIANS BY SATURDAY.

SUFFICIENT INSTABILITY SHOULD BE PRESENT MOST DAYS TO SUPPORT DIURNALLY
MODULATED CONVECTION...WITH PASSING FRONTS POSSIBLY EXTENDING
CONVECTION KEEPING CONVECTION ALIVE INTO THE OVERNIGHT HOURS. MODEL
FORECAST SOUNDINGS SHOW SOME AMOUNT OF LOW LEVEL SHEAR PRESENT...
LENDING LIMITED SUPPORT FOR ORGANIZED CONVECTION. WITH LOW LEVEL
FLOW FAVORING THE WEST...UPSLOPE ENHANCED PRECIPITATION WOULD BE
CONFINED TO THE WEST SLOPES OF THE APPALACHIANS. TEMPERATURES WILL
RUN NEAR NORMAL.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AT KCLT AND ELSEWHERE...THROUGH THE 18Z TAF PERIOD...BROAD SFC HIGH
PRESSURE WILL LINGER ACROSS THE REGION AS A MID LEVEL TROF SWEEPS
EAST OF THE MISSISSIPPI RIVER. RECENT OBSERVATIONS INDICATED
DEWPOINT DEPRESSIONS AROUND 30 DEGREES WITH LITTLE TO NO UPSTREAM
CLOUD COVER. DIURNAL CU IS EXPECTED TO REMAIN ACROSS THE EASTERN
PIEDMONT AND ALONG THE MTN RIDGES NEAR THE TN BORDER. I WILL KEEP
THE TAFS LIMITED TO A MENTION OF FEW CIRRUS WITH LIGHT NW
WINDS...MARGINALLY GUSTY AT KAVL. WIND SPEEDS ARE EXPECTED TO WEAKEN
LATE THIS AFTERNOON AND EVENING...BECOMING CALM IN MANY PLACES
OVERNIGHT. THE CENTER OF THE HIGH IS EXPECTED TO PUSH EAST OF THE
REGION ON MONDAY...LIKELY RESULTING IN A WEAK LEE TROF DEVELOPING BY
MID DAY. WINDS SHOULD SIFT FROM THE SW BY MID TO LATE MORNING. THE
RETURN FLOW IS EXPECTED TO INCREASE THE LLVL MOISTURE...SUPPORTING A
MENTION OF FEW050 CU.

OUTLOOK...A LINGERING BERMUDA HIGH COMBINED WITH A AMPLIFYING L/W
TROF OVER THE SOUTHEAST WILL GRADUALLY INCREASE LLVL MOISTURE AND
INSTABILITY THROUGH MOST OF THE WORK WEEK. THUNDERSTORM COVERAGE MAY
INCREASE EACH DAY THROUGH WEDNESDAY...WITH SCT TO NUM DIRUNAL
THUDERSTORMS LATE IN THE WEEK. RESTRICTIONS MAY OCCUR WITH PASSING
STORMS AND EACH MORNING OVER AREAS OF WET SOIL.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
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...JAT
NEAR TERM...NED
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...NED


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