Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 021432
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1032 AM EDT MON MAY 2 2016

.SYNOPSIS...
A WARM AND HUMID AIR MASS WILL REMAIN IN PLACE ACROSS THE REGION
TODAY AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. THIS FRONT
WILL SLOWLY PUSH ACROSS THE AREA ON TUESDAY. ANOTHER COLD FRONT WILL
CROSS THE AREA ON THURSDAY AND WILL BRING A COOLER AND DRIER AIR
MASS FROM CANADA THAT SHOULD PERSIST INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM...A STRONGLY POSITIVELY TILTED UPPER TROUGH WILL
CONTINUE TO DIG SOUTH AND EASTWARD ACROSS THE OHIO AND LOWER MS
VALLEY REGION TODAY. THERE IS ALREADY PLENTY OF ONGOING CONVECTION
WITHIN THE HEIGHT FALL REGION TO OUR WEST THIS MORNING.
MEANWHILE...A COLD FRONT WAS ANALYZED AT 12Z ACROSS THE TN
VALLEY...AND SHOULD TRIGGER NEW CONVECTION WITH HEATING THIS AFTN.
IN FACT...THE LATEST LAPS CAPE ANALYSIS SHOWS 1500-2000 J/KG OF
SBCAPE ACROSS THE ENTIRE PIEDMONT. AS THE TROUGH APPROACHES FROM THE
NW...0-6 KM BULK SHEAR IS EXPECTED TO BE MAINLY 20-30 KTS FOR MOST
OF THE DAY WITH BETTER SHEAR JUST TO THE NORTH AND WEST.
STILL...WITH DECENT INSTBY AND MARGINAL SHEAR WITH IMPROVING UPPER
DIVERGENCE WITHIN A RIGHT ENTRANCE REGION OF A 250 MB JET...I EXPECT
SOLID COVERAGE OF CONVECTION DEVELOPING THIS AFTN...AND CONTINUING
INTO THE EVENING HOURS. A FEW STORMS MAY BECOME STRONG TO
SEVERE...WITH HAIL LIKELY THE BIGGEST THREAT...ESP FROM THE BLUE
RIDGE AND EAST ACRS NC. AN ISOLATED FLASH FLOOD THREAT WILL ALSO
EXIST. POPS WERE TWEAKED...BUT OVERALL LINE UP WITH THIS THINKING.
THE LATEST CAMS SHOW CONVECTION BUBBLING FROM AROUND MIDDAY THRU
TONIGHT...WITH ROUNDS OF BETTER COVERAGE STARTING IN THE SOUTHERN
ZONES...THEN ACRS THE BLUE RIDGE TO THE NC PIEDMONT THIS AFTN...AND
FINALLY ACTIVITY ENTERING FROM THE WEST THIS EVENING.

WARM ADVECTION PATTERN WILL KEEP TEMPERATURES 5 TO 10 DEGREES ABOVE
NORMAL WITH RELATIVELY HIGH RH.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 330 AM EDT MONDAY...IT LOOKS LIKE THE SHORT RANGE PART OF THE
FORECAST HOLDS A CHANGE IN THE PATTERN WHICH WILL PUT AN END TO OUR
RECENT ACTIVE WEATHER REGIME. ON TUESDAY...A SURFACE WAVE SHOULD
MOVE AWAY TO THE NORTHEAST ALONG THE COLD FRONT...WHICH COMBINED
WITH A DIGGING UPPER TROF SHOULD HELP TO SLOWLY PUSH THE BOUNDARY
ACROSS THE FORECAST AREA DURING THE DAY. UPPER FORCING WILL BE WEAK
AND LOW LEVEL FLOW GRADUALLY COMES AROUND TO SOMETHING MORE
WESTERLY...WHICH DOES NOT SUGGEST MUCH IN THE WAY OF PRECIP
COVERAGE. WE MAY BEGIN THE PERIOD WITH SCATTERED PRECIP COVERAGE BUT
WITH THE BOUNDARY MOVING IN FROM THE WEST DURING THE DAY...PRECIP
PROB DIMINISHES AND MOVES EASTWARD WITH TIME. THE FCST REFLECTS THIS
DOWNWARD TREND...ESPECIALLY TUESDAY NIGHT WHEN THE BOUNDARY SHOULD
BE TO OUR EAST. IN SPITE OF THE BETTER FORCING ASSOCIATED WITH THE
INITIAL SHORT WAVE MOVING THROUGH...THIS MID/UPPER SYSTEM HAS LITTLE
IN THE WAY OF MOISTURE...THUS PRECIP CHANCES WERE CUT BACK IN MOST
PLACES. WILL HOLD ONTO SOME LINGERING CHANCE OVER THE EASTERN ZONES
IN THE EVENING...BUT THIS WILL TRANSITION TO A SMALL CHANCE ONLY
NEAR THE TN BORDER EARLY WEDNESDAY MORNING. ON WEDNESDAY...THE
MODELS SUGGEST A RELATIVE LULL BEFORE THE ARRIVAL OF THE NEXT WAVE
AND THE ACCOMPANYING MOISTURE DROPPING DOWN AROUND THE UPPER LOW
FROM THE NW. THIS SYSTEM SHOULD ARRIVE LATE IN THE DAY...ACCOUNTING
FOR AN INCREASE IN PRECIP CHANCES NEAR THE TN BORDER. SOME SHOWER
ACTIVITY COULD BREAK CONTAINMENT AND MOVE OUT OVER THE PIEDMONT IN
THE EVENING WITH THE PASSAGE OF THE MAIN VORT CENTER. IN ITS
WAKE...PRECIP CHANCES TAPER BACK TO THE NW FLOW UPSLOPE AREAS EARLY
THURSDAY MORNING. TEMPS WILL BE NEAR NORMAL TUESDAY AS THE FRONT
PASSES...WITH A COOL-DOWN BEGINNING ON WEDNESDAY WITH THE INITIAL
WAVE.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 410 AM MONDAY...THE MAIN STORY FOR THE LATE PART OF THE WEEK
WILL BE THE BIG COOL-DOWN EXPECTED FOR THURSDAY AS A DEEP UPPER LOW
ROLLS DOWN FROM THE GT LAKES AND ACROSS THE MID-ATLANTIC REGION. THE
MODELS HAVE A COOLER TREND FOR HIGH TEMPS ON THURSDAY SO ABOUT A
CATEGORY WAS CUT OFF...WHICH WILL BRING TEMPS DOWN TO SOMETHING ON
THE ORDER OF TEN DEGREES BELOW NORMAL. PRECIP CHANCES SHOULD EXPAND
OUTWARD FROM THE TN BORDER DURING THE DAY WITH STEEP LOW LEVEL LAPSE
RATES SUPPORTING SHALLOW CONVECTIVE SHOWERS MAINLY OVER THE NC
FOOTHILLS AND PIEDMONT...PERHAPS LASTING INTO THE EARLY EVENING
BEFORE DIMINISHING WITH THE LOSS OF HEATING. A CHANCE OF SHOWERS
WILL PERSIST ALONG THE TN BORDER RIGHT THROUGH FRIDAY MORNING. WITH
THE COLDEST AIR AT MID LEVELS DRIFTING OVERHEAD EARLY THURSDAY...
CANNOT RULE OUT A FEW WET SNOWFLAKES AT ELEVATIONS ABOVE 6K FEET.
ISOLATED SHOWERS COULD DEVELOP ONCE AGAIN OVER THE NC FOOTHILLS AND
PIEDMONT ON FRIDAY AFTERNOON. TEMPS WILL BEGIN TO MODERATE FROM
FRIDAY INTO THE WEEKEND. FOR THE WEEKEND...THE UPPER PATTERN REMAINS
SLOWLY PROGRESSIVE WITH THE EASTERN UPPER LOW MOVING OFF THE EAST
COAST AND AN UPPER RIDGE BUILDING IN FROM THE WEST. THIS WILL
SUPPORT HIGH PRESSURE AT THE SURFACE THAT SHOULD SPELL DRY WEATHER
WITH TEMPS GRADUALLY RETURNING TOWARD NORMAL.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
AT KCLT...THUNDERSTORM ACTIVITY WILL SHORTLY LEAVE THE AREA.
FURTHER THUNDERSTORMS ARE NOT EXPECTED UNTIL MONDAY
AFTERNOON...THOUGH SOME WIDELY SCATTERED SHOWERS MAY OCCUR IN THE
VICINITY BEFORE THEN.  MONDAY WILL BE SIMILAR TO SUNDAY WITH POSSIBLE
AFTERNOON THUNDERSTORMS AND SOUTHWESTERLY SURFACE WIND OF AROUND
10KT.  SOUTHWESTERLY SURFACE FLOW WILL MAINTAIN CLOUDS AND
SHOWER/AFTERNOON THUNDER ACTIVITY THROUGH MONDAY.  CLOUDS MAY HAVE
CEILINGS DOWN TO IFR LEVELS...ESPECIALLY IN THE MORNING.

ELSEWHERE...THUNDERSTORMS HAVE ENDED FOR THE TIME BEING...THOUGH
SOME WIDELY SCATTERED LIGHT SHOWERS WILL BE POSSIBLE OVER NIGHT.
MORE THUNDERSTORMS ARE EXPECTED TO DEVELOP MONDAY AFTERNOON AND LAST
THROUGH THE EVENING WITH SOUTHWESTERLY SURFACE WINDS OF AROUND 10KT.
WITH MOIST LOW-LEVELS AND RECENT RAINS...SOME LOW CEILINGS AND FOG
WILL BE POSSIBLE IN THE MORNING...ESPECIALLY IN PLACES PRONE TO FOG.

OUTLOOK...UNSETTLED WEATHER/OCCASIONAL CONVECTION/RESTRICTIONS ARE
EXPECTED TO CONTINUE THROUGH ABOUT TUESDAY. DRYING IS EXPECTED BY
WEDNESDAY...AND THE DRY WEATHER SHOULD PERSIST THROUGH THE END OF
THE WEEK.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       HIGH  87%     HIGH 100%     MED   71%     LOW   0%
KGSP       HIGH  90%     HIGH 100%     MED   63%     LOW   0%
KAVL       HIGH 100%     HIGH 100%     MED   62%     LOW   0%
KHKY       HIGH  97%     HIGH 100%     MED   68%     LOW   0%
KGMU       HIGH  93%     HIGH 100%     MED   67%     LOW   0%
KAND       HIGH  90%     HIGH  91%     MED   65%     LOW   0%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULE TAF ISSUANCE FLIGHT RULE CATEGORY.  COMPLET HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK:

WWW.WEATHER.GOV/GSP/AVIATION

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...PM
NEAR TERM...ARK/WJM
SHORT TERM...PM
LONG TERM...PM
AVIATION...WJM



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