Area Forecast Discussion
Issued by NWS Greer, SC

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055
FXUS62 KGSP 270610
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
210 AM EDT WED APR 27 2016

.SYNOPSIS...
WARM ATLANTIC HIGH PRESSURE WILL PERSIST OVER THE SOUTHEAST THROUGH
MIDWEEK. AFTER A WEAK COLD FRONT MOVES IN FROM THE WEST THURSDAY
NIGHT...WEAK HIGH PRESSURE WILL RETURN BRIEFLY ON FRIDAY. A LOW
PRESSURE SYSTEM WILL MOVE IN FROM THE WEST OVER THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 130 AM EDT...THE LATEST SURFACE ANALYSIS DEPICTS A WEST TO
EAST ORIENTED FRONT DRAPED ACROSS THE MID ATLANTIC REGION EARLY THIS
MORNING. OUTFLOWS FROM EARLIER CONVECTION ALONG THIS BOUNDARY ARE
GENERATING NOCTURNAL CONVECTION FARTHER SOUTH FROM EASTERN KY TO
SOUTHERN VA...BUT THE BOUNDARY IS EXPECTED TO REMAIN NORTH OF OUR
FORECAST AREA THROUGH THE NEAR TERM PERIOD. MEANWHILE...
SOUTHWESTERLY FLOW AT LOW LEVELS WILL PERMIT MOISTURE TO GRADUALLY
RETURN TO THE REGION TODAY ALONG WITH WARMER TEMPERATURES. THIS WILL
RESULT IN SLIGHTLY BETTER INSTABILITY IN VERTICAL PROFILES THAN WERE
OBSERVED ON TUESDAY...WITH MLCAPE NUMBERS LIKELY PEAKING AT 1500 TO
2000 J/KG LATE DAY. LOW LEVEL WIND CONVERGENCE WILL REMAIN GREATEST
OVER THE MOUNTAINS THIS AFTERNOON...WITH ADDITIONAL WEAK FORCING
OVER THE NORTHERN FOOTHILLS/PIEDMONT. WILL FEATURE SOLID CHANCES FOR
TSRA IN NORTHERN AND WESTERN SECTIONS LATE IN THE DAY AND TAPER DOWN
TO SLIGHT CHANCES SOUTHEAST. MAXES SHOULD REACH THE MID 80S OUTSIDE
OF THE MOUNTAINS AND EVEN AROUND 80 IN LOWER MOUNTAIN VALLEYS
DESPITE SOME HIGH CLOUDS.

CONVECTIVE OUTFLOWS WILL GET A BIT CLOSER FOR TONIGHT...BUT WITH
DIURNAL ACTIVITY TO THE NORTH AND WEST LIKELY DIMINISHING BEFORE
REACHING THE SOUTHERN APPALACHIANS. EXPECT A MILD NIGHT WITH MINS
GREATER THAN 10 DEGREES ABOVE CLIMO AND CONTINUED NOCTURNAL
CONVECTIVE CHANCES...HIGHEST IN NW SECTIONS AND LOWEST SE.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
AS OF 200 PM TUE...WEDNESDAY NIGHT OUR AREA WILL REMAIN IN THE WARM
SECTOR OF THE WEAKENING CENTRAL CONUS SYSTEM. GENERALLY MODELS
INDICATE NEARLY STATIONARY WARM FRONT EXTENDING FROM THE CORN
BELT TO THE DELMARVA REGION...AND COLD FRONT MOVING THRU THE LOWER
OHIO/TENN VALLEYS. THE COLD FRONT IS RATHER ILL-DEFINED. THERE IS
SOME NOTABLE SPREAD AS TO HOW MUCH INSTABILITY WILL BE AVAILABLE
OVER THE CWFA WED NIGHT...AND THAT MAY DEPEND ON HOW MUCH THE
ATMOSPHERE IS WORKED OVER WED AFTN. I WILL ALLOW POPS TO DIMINISH
SLOWLY OVERNIGHT. THE COLD FRONT WILL CONTINUE TO APPROACH THRU
THURSDAY...BUT NWLY WINDS AND LO-LEV DRYING DO NOT DEFINITIVELY
OCCUR UNTIL THU NIGHT. SLIGHTLY BETTER CAPE IS EXPECTED TO DEVELOP
DIURNALLY THU...AND WITH THE SYSTEM HAVING MOVED CLOSER SHEAR
PARAMETERS ARE STRONGER THAN WED. ON THAT NOTE POPS WILL RISE
INTO THE LIKELY RANGE OVER A GREATER SHARE OF THE AREA THU...AND
CURRENT INCLUSION OF THE AREA IN MARGINAL RISK ON THE SPC DAY 3
OUTLOOK SEEMS APPROPRIATE.

HEIGHTS WILL RISE OVER THE SOUTHEAST FRIDAY UNDER A SHORTWAVE
RIDGE. MODELS AGREE THAT A POTENT SHORTWAVE /THE REMNANT OF THE
DEFUNCT PLAINS LOW/ WILL ROUND THE CREST OF THE RIDGE DURING THE
DAY...BUT VARY WIDELY IN THE PRECISE LOCATION. THE EC IS STRONGEST
AND FASTEST IN ITS DEPICTION OF THE WAVE EVOLUTION...AND WOULD
SUGGEST IT WILL CROSS JUST TO OUR NORTH FRI AFTN. COMPARE THIS TO
THE NAM WHICH EXPECTS THE WAVE TO BE OVER LAKE HURON AT 00Z SAT. IF
THE EC SOLUTION WERE TO VERIFY...OUR NC FOOTHILLS/PIEDMONT ZONES
MIGHT EXPERIENCE SOME ISOLD TSTMS. FOR NOW THE BETTER CONSENSUS
IS FOR A DRY FCST. TEMPS WILL BE WARMER FRI UNDER CLEARER SKIES
AND HIGHER PARTIAL THICKNESS VALUES.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 210 PM TUESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SATURDAY WITH UPPER RIDGING AMPLIFYING OVER THE SE CONUS WHILE A
WELL DEFINED EMBEDDED UPPER SHORTWAVE MOVES OFF THE NC COAST. AT THE
SAME TIME...DEEP AND PERSISTENT UPPER TROFFING OVER MOST OF THE
WESTERN CONUS WILL GRADUALLY LIFT NORTHEASTWARD AS MULTIPLE CLOSED
LOWS SPIN UP OVER THE WEEKEND. MOST OF THE UPPER LEVEL ENERGY
ASSOCIATED WITH THE TROF WILL LIKELY REMAIN WEST OF THE CWFA AS THE
RIDGE PERSISTS INTO NEXT WEEK...HOWEVER SOME PVA COULD REACH THE
WESTERN CAROLINAS BY THE END OF THE PERIOD.

AT THE SFC...WEAK LOW PRESSURE AND ITS ASSOCIATED COLD FRONT WILL BE
MOVING OFF THE ATLANTIC COAST BY LATE FRI/EARLY SAT. IN ITS
WAKE...ANOTHER CANADIAN HIGH WILL BEGIN TO PUSH BACK INTO THE REGION
FROM THE NORTH AND ESTABLISH A WEAK CAD PATTERN OVER THE CAROLINAS.
AT THE SAME TIME...A LOW DEVELOPS OVER THE SOUTHERN PLAINS AND MOVES
NE TOWARDS THE SOUTHERN GREAT LAKES. AS THE LOW MOVES TO OUR NW IT
WILL WEAKEN THE CAD AS IT PUSHES THE HIGH NE. IT WILL ALSO ALLOW
MOIST SELY FLOW TO OVERSPREAD THE FCST AREA BY EARLY NEXT WEEK. THE
COLD FRONT ASSOCIATED WITH THE LOW APPEARS TO AT LEAST PARTIALLY
WASH OUT AS IT MOVES INTO THE CWFA SO IT PROBABLY WON`T HAVE MUCH
IMPACT ON TEMPS. AS FOR THE SENSIBLE FCST...THINGS SHOULD START OUT
DRY WITH POPS STEADILY INCREASING THRU THE DAY ON SAT AND SUN. BY
SUN AFTERNOON...SCATTERED TO WIDESPREAD SHOWERS AND TS WILL LIKELY
DEVELOP ACROSS THE FCST AREA. THEY COULD LINGER WELL INTO MON...BUT
THE CHANCES ARE LOWER FOR ANY WIDESPREAD COVERAGE. I KEPT A SOLID
CHANCE OVER THE CWFA FOR THE REST OF THE PERIOD WITH CONTINUED MOIST
SLY FLOW IN THE BNDY LAYER. TEMPS SHOULD MODERATE OVER THE
WEEKEND...HOWEVER VALUES ARE EXPECTED TO REMAIN ABOVE CLIMO FOR LATE
APRIL.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE...ALL TERMINAL LOCATIONS TODAY WILL REMAIN IN
THE WARM SECTOR SOUTH OF A STALLED FRONT ZONE OVER THE VIRGINIAS AND
A SLOWLY APPROACHING COLD FRONT FROM THE WEST NEAR THE MS RIVER
VALLEY. FEW TO SCATTERED CUMULUS WILL DEVELOP WITH HEATING AND
CIRRUS BLOWOFF FROM UPSTREAM DECAYING CONVECTION MAY PROVIDE SOME
CEILINGS AT TIMES. THE BEST CHANCES OF SCATTERED THUNDERSTORMS
AFFECTING THE NC TERMINALS WILL OCCUR LATE DAY THROUGH EARLY
EVENING...WHILE CHANCES LOOK EVEN LESS AT THE SC TERMINALS. EXPECT
MAINLY SW WINDS...WITH LOW END GUSTS AT TIMES...EXCEPT LIGHTER AND
MORE VARIABLE AT KAVL THROUGH THE PERIOD.

OUTLOOK...PRECIPITATION CHANCES AND ASSOCIATED RESTRICTIONS SHOULD
INCREASE INTO THURSDAY AHEAD OF A COLD FRONT APPROACHING FROM THE
NORTHWEST. SOME DRYING IS EXPECTED ON FRIDAY...WITH VFR
CONDITIONS...BEFORE UNSETTLED WEATHER RETURNS FROM THE WEST OVER THE
WEEKEND. MORE RESTRICTIONS ARE POSSIBLE STARTING SATURDAY NIGHT.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z
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%     MED   79%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH  97%     HIGH 100%     HIGH 100%

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...WIMBERLEY
NEAR TERM...HG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...HG



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