Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 301825
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
225 PM EDT WED JUL 30 2014

.SYNOPSIS...
CANADIAN HIGH PRESSURE OVER THE AREA WILL LEAD TO WELL BELOW NORMAL
TEMPERATURES MORE TYPICAL OF LATE SUMMER OR EARLY AUTUMN. AS THE
SURFACE HIGH WEAKENS...MOISTURE WILL RETURN FOR THE WEEKEND
INCREASING THE CHANCES OF WIDESPREAD SHOWERS AND THUNDERSTORMS.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 215 PM WED...IN THE VERY NEAR TERM A QUIET AFTERNOON WILL
CONTINUE WITH GENERALLY MOSTLY SUNNY CONDITIONS AND PLEASNT MAX
TEMPS MORE LIKE MID TO LATE SEPTEMBER.

IN REGARD TO THE BIG PICTURE....SOME CHANGES ARE ANTICIPATED TO
GRADUALLY TAKE PLACE BY LATE THU. THE UPPER TROUGH AXIS OVER THE
EASTERN U.S. IS FORECAST BY THE MODELS TO BECOME RE-ESTABLISHED TO
THE WEST OF THE APPALACHIANS AS ENERGY FROM THE CENTRAL ROCKIES DIVES
SE. AT THE SAME...A STATIONARY FRONT NEAR THE COAST WILL BEGIN TO
MOVE SLOWLY WESTWARD AS A WARM FRONT. HENCE BY LATE TONIGHT...
BOUNDARY LAYER WINDS WILL BEGIN TO VEER TO THE E-SE WHICH WILL
ADVECT ATLANTIC MOISTURE INTO THE AREA AND PROVIDE WEEK MECHANICAL
LIFT ACROSS THE HIGHER TERRAIN. PLUS BY THU AFTERNOON...A VORT MAX
IS FORECAST TO APPROACH FROM THE SW AND SWING ACROSS THE MOUNTAINS
THU AFTERNOON. ALL THIS COMBINED WILL GIVE US AN INCREASING CHANCE
FOR SHOWERS ON THU....WITH THE BEST COVERAGE OVER THE NC MOUNTAINS
DURING THE AFTERNOON HOURS. WILL LIMIT POPS TO THE CHANCE RANGE AT THIS
TIME AS INSTABILITY APPEARS LIMITED WITH ONLY A COUPLE HUNDRED
JOULES OF CAPE EXPECTED. ONLY WIDELY SCATTERED SHOWERS ARE EXPECTED OUTSIDE
THE MOUNTAINS. WITH INCREASING CLOUDS TONIGHT...MIN TEMPS SHOULD
BE SEVERAL DEGREES HIGHER THAN LAST NIGHT. CONSIDERABLE CLOUDINESS
IS ANTICIPATED ON THU WHICH WILL CONTINUE TO HOLD MAX TEMPS BELOW
CLIMO.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 220 PM...ON FRIDAY...MOISTURE ACROSS THE SOUTHEAST U.S. SHOULD
INCREASE SHARPLY AS ATLANTIC MOISTURE ADVECTS WEST AND MERGES WITH
MOISTURE ASSOCIATED WITH A FADING SOUTHERN PLAINS LOW. FORECAST
SOUNDINGS INDICATE THAT PW WILL INCREASE TO AROUND 1.75 INCHES BY
FRIDAY MORNING...WITH LCLS BELOW 2 KFT. NAM12 SHOWS ISENTROPIC LIFT
WILL STRENGTHEN BETWEEN 305K-315K FRI MORNING...PERSISTING THROUGH
THE AFTERNOON. LOW LEVEL LIFT WILL LIKELY BE AUGMENTED ALONG THE
EAST FACING SLOPES AS WINDS REMAIN FROM THE SOUTHEAST AROUND 20 KTS.
IN ADDITION...A BROAD AREA OF MID LEVEL Q-VECTOR CONVERGENCE WILL
REMAIN ACROSS THE SOUTHEAST...EAST OF AN AMPLIFYING L/W TROF CENTERED
ACROSS THE MISSISSIPPI RIVER VALLEY. THE COMBINATION OF THE DEEP
LIFT...ABUNDANT MOISTURE...AND WEAK INSTABILITY SHOULD SUPPORT
NUMEROUS SHOWERS AND THUNDERSTORMS ON FRIDAY... I WILL FORECAST
GENERALLY LIKELY POPS ALONG AND WEST OF I-85...HIGH CHC EAST. THE
LACK OF INSTABILITY ACROSS THE MTNS AND FOOTHILLS MAY SUPPORT ONLY
SHOWERS...THUNDERSTORMS APPEAR POSSIBLE ALONG AND EAST OF I-85.
PERIODS OF RAIN...ENE WINDS...AND THICK CLOUD COVER SHOULD LIMIT
DAYTIME HEATING...KEEPING HIGHS IN THE 70S ACROSS THE MTNS TO
WESTERN PIEDMONT.

ON SATURDAY...THE RIDGE OF SFC HIGH PRESSURE SHOULD TREND WEAKER
THROUGH THE DAY. HOWEVER...SHALLOW RIDGING IS EXPECTED TO LINGER
ALONG AND EAST OF THE HIGH TERRAIN. DEEP FORCING IS EXPECTED TO
CONTINUE ACROSS THE FORECAST AREA...AIDED BY THE APPROACH OF THE
AMPLIFYING MID LEVEL TROF. I WILL FORECAST A RANGE IN POPS...LIKELY
POPS ACROSS THE MTNS TO HIGH CHC EAST. LLVL WINDS ARE EXPECTED TO
VEER FROM THE SOUTHWEST...SUPPORTING TEMPERATURES 4 TO 6 DEGREES
WARMER THAN FRIDAY. FORECAST SOUNDINGS INDICATE WEAK INSTABILITY
ACROSS THE FORECAST AREA...SUPPORTING A MENTION OF THUNDERSTORMS FOR
ALL ZONES.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 200 PM WEDNESDAY...THE MEDIUM RANGE WILL START OUT WITH A
FAIRLY DEEP H5 TROF AXIS EXTENDING FROM THE GREAT LAKES SOUTH TO THE
LWR MS VLY AT 00Z SUNDAY. THE TROF WILL GRADUALLY WEAKEN/SHEAR OUT
EARLY NEXT WEEK...BUT SOME DEGREE OF TROFINESS WILL LINGER THRU
WEDNESDAY. A QUASI-STATIONARY FRONTAL ZONE WILL LINGER PARALLEL TO
THE SWLY UPR FLOW ALONG/JUST INLAND OF THE EAST COAST...KEEPING THE
CWFA IN A MOIST/UNSETTLED ENVIRONMENT INTO EARLY NEXT WEEK. THE
FRONT WILL WASH OUT BY WEDNESDAY...PER THE CONSENSUS OF THE MEDIUM
RANGE GUIDANCE.

SO BLENDING IN THE NEW GUIDANCE AND WPC GUIDANCE...I WILL FCST ABOVE
NORMAL POPS FOR SUNDAY AND MONDAY (HIGH-END CHC TO LIKELY)...AND
TAPERING SOMEWHAT TO SHOTGUN LOW-MID CHC FOR TUESDAY AND WEDNESDAY.
TEMPS WILL START OUT WITH BELOW NORMAL HIGHS (DUE TO
CLOUDS/PRECIP)...AND NEAR NORMAL LOWS THRU MONDAY...THEN AFTN HIGHS
WILL TREND TOWARD NORMAL BY WEDNESDAY WITH CONTINUED NEAR NORMAL
LOWS.

THE EXPECTED DECENT COVERAGE OF PRECIP OVER SEVERAL PERIODS LOOKS TO
BE MAINLY SUPPORTED BY PERSISTENT UPPER DIVERGENCE WITHIN RIGHT
ENTRANCE REGION OF A NEARLY STATIONARY JET STREAK ALONG THE
APPALACHIANS. HOWEVER...QG FORCING AND LLVL TRIGGERING WILL BE ONLY
MARGINALLY SUPPORTIVE...WITH THE BETTER MID LVL FORCING TO THE
NORTH...AND LLVL JET AND INSTBY TO THE EAST. SO CONFIDENCE IS LOW ON
ANY SEVERE WX OR HEAVY RAIN THREAT AT THIS TIME.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
AT KCLT...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD DESPITE
INCREASING MOISTURE AS BOUNDARY LAYER WINDS TURN TO THE SE. LOW VFR
CIGS ARE A GOOD BET BY LATE TONIGHT. SFC WINDS WILL BE LIGHT.

ELSEWHERE...MUCH THE SAME AS KCLT WITH VFR CONDITIONS PREVAILING
THROUGH THE PERIOD WITH THE EXCEPTION OF POSSIBLE MVFR FOG AT KAVL
EARLY THURSDAY MORNING. SHOWER CHANCES WILL BE INCREASING ON THU BUT
POPS TOO LOW BEFORE 18Z TO MENTION IN TAFS.

OUTLOOK...MOISTURE WILL CONTINUE TO INCREASE THROUGH THE REMAINDER
OF THE WORK WEEK AS A WARM FRONT APPROACHES FROM THE EAST AND
SOUTHEASTERLY FLOW CONTINUES. UNSETTLED WEATHER WITH ENHANCED
PRECIPITATION CHANCES ALONG WITH MORNING FOG/STRATUS THROUGH THE
WEEKEND.

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  91%     HIGH  95%
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...ARK
NEAR TERM...LG
SHORT TERM...NED
LONG TERM...ARK
AVIATION...LG





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