Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 281842
AFDGSP

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

.SYNOPSIS...
A COOLER AND DRIER AIRMASS WILL REMAIN IN PLACE AS THE WEEKEND COMES
TO AN END...AND WILL KEEP RAIN CHANCES WELL BELOW NORMAL TO START
THE WORK WEEK. ANOTHER FRONT WILL APPROACH THE SOUTHEAST BY THE
MIDDLE OF THE WEEK...AND A MOISTER AIRMASS TYPICAL OF EARLY JULY
WILL MOVE IN. THIS WILL LEAD TO INCREASED SHOWER AND THUNDERSTORM
CHANCES LATER IN THE WEEK...WITH HIGH TEMPERATURES RETURNING TO NEAR
AVERAGE LEVELS.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 230 PM...THROUGH TONIGHT...A BROAD SFC HIGH PRESSURE WILL
LINGER ACROSS THE REGION AS A MID LEVEL TROF SWEEPS EAST OF THE
MISSISSIPPI RIVER. LATEST FOOTHILL AND PIEDMONT OBSERVATIONS
INDICATED THAT TEMPERATURES HAVE RISEN AROUND 80 DEGREES WITH 30
DEGREE DEWPOINT DEPRESSIONS. LATEST SATELLITE IMAGES SHOWED ONLY A
FEW CU ACROSS THE LAKELANDS AND NEAR THE TN BORDER. THE COMBINATION
OF CLEAR TO MOSTLY CLEAR SKY CONDITIONS...LIGHT TO CALM WINDS...AND
WIDE DEWPOINT DEPRESSIONS SHOULD RESULT IN LOW TEMPERATURES 5 TO 7
DEGREES BELOW NORMAL TONIGHT.

THE CENTER OF HIGH PRESSURE WILL SHIFT NORTHEAST OF THE REGION ON
MONDAY. A WEAK LEE TROF IS EXPECTED TO DEVELOP BY MID
DAY...DEEPENING SLIGHTLY DURING THE AFTERNOON. AS A RESULT...LIGHT
SW WINDS SHOULD DEVELOP BY MID MORNING AND REMAIN THROUGH THE REST
OF THE DAY. RETURN FLOW SHOULD SUPPORT HIGH TEMPERATURES A DEGREE OR
TWO WARMER THAN TODAY...WITH A 5 DEGREE RISE IN DEWPOINT VALUES.
OVERALL...LLVL MOISTURE SHOULD INCREASE...BUT TOO LOW TO YIELD ANY
SBCAPE EAST OF THE MTNS. HOWEVER...THE 12Z NAM INDICATES THAT CAPE
AROUND 500 J/KG MAY SPREAD ACROSS THE WESTERN NC MTNS DURING THE
LATE AFTERNOON HOURS. I WILL CONTINUE TO FORECAST SCHC POPS TO
HIGHLIGHT THE POSSIBILITY OF UPSTREAM CONVECTION REACHING THE NC
BORDER COUNTIES...THEN DISSIPATING.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
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 /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 230 PM EDT SUNDAY...RELATIVELY DEEP H5 TROUGHING REMAINS IN
PLACE OVER THE EASTERN HALF OF THE CONUS AT THE BEGINNING OF THE
MEDIUM RANGE. AT THE SURFACE...A BACKDOOR FRONT IS DRAPED ACROSS THE
OHIO RIVER VALLEY AND THE MID-ATLANTIC STATES. MODELS DISAGREE ON
HOW FAR SOUTH THE ASSOCIATED MOISTURE/FORCING ARE ALLOWED TO
PENETRATE...THOUGH EITHER SOLUTION ALLOWS FOR THE ENHANCEMENT OF
DIURNAL POPS WITH SOME CONTINUATION OVERNIGHT THURSDAY AND INTO
FRIDAY. THE  MID-LEVEL TROUGH WILL AMPLIFY SLIGHTLY ON FRIDAY AS A
SHORTWAVE PROPAGATES AROUND THE BASE OF THE TROUGH INTO
SOUTHEAST...BEFORE DEAMPLIFYING SIGNIFICANTLY ON SATURDAY AND SUNDAY
AS THE BLOCKING PATTERN BREAKS DOWN. A SURFACE FRONT WILL LIFT
TOWARDS THE SOUTHERN APPALACHIANS...AND WASHES OUT AS IT CROSSES
INTO THE FORECAST AREA ON SATURDAY. THOUGH WEAK...LIFT FROM THE
FRONT AND MOIST SOUTHWESTERLY FLOW WILL RAISE POPS ABOVE CLIMO ONCE
AGAIN ON SATURDAY AFTERNOON/EVENING...WITH ENOUGH INSTABILITY
PRESENT THAT SOME OF THE COVERAGE COULD PERSIST INTO THE OVERNIGHT.
THE FRONTAL PASSAGE WILL BRING LITTLE SENSIBLE CHANGE IN
AIRMASS...AND THE MOST PROMINENT SURFACE FEATURE SUNDAY AND MONDAY
WILL BE THE SEMI-PERMANENT BERMUDA HIGH AS THE UPPER PATTERN
FLATTENS OUT. THE GLOBAL MODELS DISPLAY MIXED SIGNALS AT THE END OF
THE PERIOD...THOUGH TAPERING OF POPS BACK DOWN TO NEAR CLIMO APPEARS
LIKELY AT THIS POINT.

MAX TEMPS WILL BE JUST BELOW AVERAGE AT THE BEGINNING OF THE
PERIOD...INCREASING SLIGHTLY EACH DAY OF THE MEDIUM RANGE AS HEIGHTS
RISE TO A FEW DEGREES ABOVE CLIMO BY THE END OF THE PERIOD. MIN
TEMPS WILL HOVER JUST ABOVE CLIMO THROUGH THE PERIOD.

&&

.AVIATION /19Z 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...

            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...LEV
NEAR TERM...NED
SHORT TERM...WJM
LONG TERM...LEV
AVIATION...NED


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