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Area Forecast Discussion

506
FXUS62 KGSP 021354
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
954 AM EDT TUE SEP 2 2014

.SYNOPSIS...
CONTINUED SOUTHERLY FLOW AROUND A BERMUDA HIGH WILL PROVIDE MOISTURE
FOR DIURNAL SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING
AHEAD OF A WEAK COLD FRONT THAT WILL PUSH THROUGH THE REGION
OVERNIGHT.  THIS FRONT WILL HAVE LITTLE TO NO EFFECT IN REDUCING
PRECIPITATION CHANCES ACROSS THE REGION FOR WEDNESDAY AND THROUGH
THE REST OF THE WORK WEEK AS ABOVE MENTIONED BERMUDA HIGH REGAINS
CONTROL LEADING TO CONTINUED AFTERNOON CONVECTION CHANCES.  ANOTHER
COLD FRONT WILL SWEEP THROUGH THE REGION OVER THE WEEKEND PROVIDING
AN ADDITIONAL FOCUS FOR THUNDERSTORMS ON SATURDAY AND SUNDAY.
BUILDING HIGH PRESSURE WILL HIGHLIGHT THE WEATHER PATTERN FOR THE
START OF THE NEXT WORK WEEK LEADING TO COOLER TEMPERATURES AND MORE
STABLE WEATHER.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM...FAIRLY QUIET AROUND THE REGION. SATELLITE IMAGERY
SHOWS CLEAR SKY OVER MOST OF THE FCST AREA WITH THE EXCEPTION OF THE
LAKELANDS...AND FOG LIFTING TO STRATUS OVER THE MTN VALLEYS. WILL
ADJUST SKY COVER TREND ACCORDINGLY. AREA RADARS WERE ALSO QUIET...SO
BASED ON THE LACK OF CLOUDS...WILL PUSH BACK THE ONSET OF DEEP
CONVECTION. TEMPS LOOK OK.

REMAINDER OF PREVIOUS DISCUSSION...

UPPER RIDGE ACROSS THE SERN CONUS IS SUPPRESSED TODAY AND TONIGHT AS
SHORT WAVES MOVE ACROSS THE AREA IN THE DEVELOPING WLY FLOW. AT THE
SFC...A WEAK COLD FRONT MOVES INTO THE AREA LATE THIS AFTERNOON OR
THIS EVENING AND STALLS. MODERATE INSTABILITY DEVELOPS OVER THE AREA
WITH GOOD HEATING AND COPIOUS LOW LEVEL MOISTURE. WITH THE INCREASED
FORCING AND STRONGER INSTABILITY...THE GUIDANCE IS SUGGESTING BETTER
CONVECTIVE COVERAGE TODAY ACROSS THE BOARD. ALTHOUGH...COVERAGE IS
STILL EXPECTED TO BE HIGHER ACROSS THE MTNS WHERE THE FORCING IS
BETTER. IN FACT... ISOLATED SEVERE STORMS WILL BE MORE LIKELY TODAY
AS SHEAR...THOUGH NOT STRONG...DOES INCREASE. DCAPE AND SFC DELTA
THETA-E VALUES WILL BE ON THE INCREASE AS WELL. CONVECTION MAY
LINGER LONGER THRU THE EVENING...AND POSSIBLY INTO THE EARLY
OVERNIGHT HOURS GIVEN THE STALLED BOUNDARY. HIGHS WILL BE WELL ABOVE
NORMAL ONCE AGAIN WITH HEAT INDEX VALUES NEAR 100 ACROSS THE SERN
CWFA. LOWS TONIGHT ALSO CONTINUE WELL ABOVE NORMAL...WITH ANOTHER
NIGHT OF DENSE MTN VALLEY FOG LIKELY.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM EDT TUESDAY...THE SHORT TERM PERIOD INITIALIZES
WEDNESDAY MORNING WITH ELONGATED UPPER RIDGE CENTERED OVER THE DEEP
SOUTH AND PERSISTENT BERMUDA HIGH DOMINATING LOW LEVEL FLOW.  CLOSER
TO HOME...REMNANT COLD FRONTAL BOUNDARY WILL BE PUSHING INTO THE
SOUTHERN TIER OF THE FORECAST AREA AS HIGH PRESSURE BUILDS TO THE
NORTH.  CONVECTION WILL LIKELY BE LIMITED EARLY ON WEDNESDAY AS THE
FRONT SLOWS WITH LITTLE FORCING IN THE REGION.  MODELS INDICATE
BUILDING INSTABILITY DURING THE AFTERNOON WITH THE FRONTAL MOISTURE
AXIS DISSECTING THE FORECAST AREA LEADING TO ENHANCED INSTABILITY
ACROSS THE UPSTATE AND PORTIONS OF NORTHEAST GA AND THE SOUTHWEST NC
MOUNTAINS...DECREASING TO THE NORTH.  FORECAST WILL FEATURE
INCREASING DIURNAL POPS WITH SCATTERED/NUMEROUS SHOWERS AND
THUNDERSTORMS ACROSS THE SOUTHWEST MOUNTAINS WHILE
ISOLATED/SCATTERED CONVECTION IS FORECAST ELSEWHERE.  AS STATED
ABOVE...PROFILES WILL FEATURE STEEP LAPSE RATES LEADING TO MODERATE
INSTABILITY POSSIBLY SUPPORTIVE OF STRONG/SEVERE CONVECTION WITH
DOWNBURST WINDS AND HAIL BEING PRIMARY THREATS.

AS HIGH PRESSURE SLIDES BY TO THE NORTH...BERMUDA HIGH WILL LIKELY
REGAIN CONTROL LEADING TO PREDOMINATE SOUTHERLY FLOW.  AS A
CONSEQUENCE...LINGERING SEMI STALLED MOISTURE AXIS WILL SLOWLY
MIGRATE NORTHWARD AS A WARM FRONT ACROSS THE FORECAST AREA ON
THURSDAY.  POPS ON THURSDAY WILL ONCE AGAIN INCREASE DIURNALLY AS
PROFILES DESTABILIZE LEADING TO SCATTERED/NUMEROUS SHOWERS AND
THUNDERSTORMS REGIONWIDE WITH THE BEST CHANCES ONCE AGAIN RESIDING
ALONG THE HIGH TERRAIN.  THAT SAID...CONVECTION WILL LIKELY BE MOST
ENHANCED ALONG AND NEAR WARM FRONTAL AXIS AS IT SWEEPS NORTHWARD
THROUGH THE REGION.  PROFILES WILL RESEMBLE THAT OF WEDNESDAY WITH
LOW LEVEL HEATING LEADING TO STEEPENING LAPSE RATES AND NEARLY
1500J/KG SBCAPE WITH MINIMAL SHEAR.  TEMPERATURES THROUGH THE SHORT
TERM PERIOD WILL REMAIN AT OR JUST ABOVE NORMAL LEVELS DESPITE WEAK
COLD FROPA AT FORECAST INITIATION.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 330 AM EDT TUESDAY...LONG RANGE MODELS REMAIN IN AGREEMENT
WITH THE OVERALL PATTERN THROUGH THE EXTENDED RANGE PERIOD WHICH
INITIALIZES ON FRIDAY MORNING WITH DEEP LAYER RIDING IN CONTROL
ACROSS THE SOUTHEAST.  UPPER TROF PUSHING THROUGH CENTRAL ONTARIO
WILL HAVE SPREAD A COLD FRONT SOUTHWARD THROUGH THE GREAT LAKES
REGION...WESTWARD THROUGH THE MID MISSISSIPPI RIVER VALLEY.
CONTINUED SOUTHERLY FLOW INTO THE WEEKEND WILL LEAD TO DIURNAL
CONVECTIVE CHANCES WITH SOLID CHANCE POPS FORECAST ON FRIDAY AND
SATURDAY AHEAD OF APPROACHING FRONT.  ABOVE MENTIONED COLD FRONT IS
PROGGED TO ENTER THE MOUNTAINS SATURDAY EVENING WITH GRADUAL SLOWING
LIKELY DURING THE OVERNIGHT.  THUS THE FORECAST WILL FEATURE LIKELY
LEVEL POPS OVER THE HIGH TERRAIN ON SATURDAY EVENING WITH SOLID
CHANCE POPS ACROSS NORTHEAST GA AND THE NC/SC PIEDMONT.  FRONTAL
BOUNDARY WILL CONTINUE SLOWED FORWARD PROPAGATION THROUGH THE REST
OF THE FORECAST AREA ON SUNDAY LEADING TO PERSISTENT CHANCE LEVEL
POPS WITH POSSIBLE SHORTWAVE ENHANCEMENT ACROSS THE NORTH.  HIGH
PRESSURE WILL SPILL INTO THE REGION TAKING ON A WEAK EARLY
METEOROLOGICAL FALL WEDGE CONFIGURATION ON MONDAY...LASTING INTO
WEDNESDAY.  EXPECTING LOWERED PRECIPITATION CHANCES COINCIDING WITH
COOLER BELOW NORMAL TEMPERATURES THROUGH MIDWEEK BEFORE DEEP LAYER
SOUTHEAST RIDGING RESUMES LEADING TO MODERATING TEMPERATURES.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
AT KCLT...THIN HIGH CLOUDS AND LIGHT SLY WIND THIS MORNING WILL GIVE
WAY TO DEVELOPING HIGH BASED CU AND SWLY WINDS FOR THE EARLY
AFTERNOON. THE CU BECOMES BKN BY LATE AFTERNOON WITH CONTINUED SWLY
WINDS. SHORTWAVES MOVING INTO WESTERN NC FROM THE NW LATE DAY COULD
ALLOW TSRA TO MAKE A RUN TOWARD THE PIEDMONT AGAIN...AND PROB30 FOR
TSRA AFTER 21Z AND INTO THE EVENING APPEARS WARRANTED. BKN HIGH
BASED CU LINGERS INTO THE OVERNIGHT WITH LIGHT SLY WINDS. FOR NOW...
DO NOT EXPECT ANY VSBY RESTRICTIONS OVERNIGHT...BUT THAT COULD
CHANGE IF RAIN DOES FALL AT THE AIRFIELD AND SKIES CLEAR.

ELSEWHERE...CIGS AND VSBY RESTRICTIONS HAVE BEEN TEMPO AND VARIABLE
AT KAVL THIS MORNING. STILL A CHANCE FOR A RESTRICTION UNTIL SHORTLY
AFTER DAYBREAK. OTHERWISE...THIN HIGH CLOUDS AND LIGHT SWLY WIND
THIS MORNING WILL GIVE WAY TO DEVELOPING HIGH BASED CU AND STRONGER
SWLY WINDS FOR THE EARLY AFTERNOON. KAVL WILL SEE CONTINUED NWLY
WINDS. PROB30 FOR TSRA APPEARS WARRANTED AT ALL LOCATIONS FOR LATE
AFTERNOON INTO THE EVENING. VCTS INCLUDED FOR EARLY AFTERNOON AT
KAVL. SHOULD BE ANOTHER ROUND OF VSBY AND CIG RESTRICTIONS AT KAVL
OVERNIGHT. HOWEVER...HAVE LIMITED TO MVFR VSBY AND IFR CIGS FOR
NOW...BUT THE COULD BE WORSE. ELSEWHERE...DO NOT EXPECT ANY VSBY
RESTRICTIONS OVERNIGHT...BUT THAT COULD CHANGE IF RAIN DOES FALL AT
THE AIRFIELDS AND SKIES CLEAR.

OUTLOOK...GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH THE REST OF
THE WEEK...BUT RESTRICTIONS ARE LIKELY EARLY EACH MORNING IN THE
MOUNTAIN VALLEYS DUE TO LOW CLOUDS AND FOG. DIURNALLY DRIVEN
SHRA/TSRA ARE EXPECTED EACH AFTERNOON AND EARLY EVENING...WITH THE
MOST COVERAGE OVER THE MOUNTAINS.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-14Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  90%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     MED   75%
KAVL       HIGH  99%     HIGH 100%     HIGH 100%     MED   64%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     MED   75%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  90%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     MED   75%

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...CDG
NEAR TERM...PM/RWH
SHORT TERM...CDG
LONG TERM...CDG
AVIATION...RWH






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