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Area Forecast Discussion

952
FXUS62 KGSP 220728
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
328 AM EDT FRI AUG 22 2014

.SYNOPSIS...
A BROAD UPPER LEVEL RIDGE OF HIGH PRESSURE WILL CONTINUE TO PROVIDE
VERY WARM TEMPERATURES ACROSS THE REGION INTO SATURDAY. A BACK DOOR
COLD FRONT WILL THEN PUSH INTO THE AREA FROM NORTHEAST USHERING IN
COOLER TEMPERATURES STARTING SUNDAY. TEMPERATURES WILL GRADUALLY
RETURN TO NORMAL THROUGH NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
SHOULD BE QUIET FOR THE REMAINDER OF THE PRE-DAWN HOURS WITH ONLY
SOME HIGH LEVEL CONVECTIVE DEBRIS CLOUDS. MEANWHILE...AN MCS SHOULD
BREAK UP TO THE N AS IT MOVES OVER THE CENTRAL APPALACHIANS.

FOR THE NEXT 24 HOURS...THE UPPER PATTERN WILL UNDERGO SOME
AMPLIFICATION...ESPECIALLY WITH A RIDGE AXIS OFF TO OUR WEST THAT
WILL ALSO SHARPEN. AT THE SAME TIME...AN UPPER TROF WILL DIG OFF THE
EAST COAST. THIS WILL GRADUALLY VEER THE UPPER FLOW AROUND TO NNW BY
SATURDAY MORNING...THAT SHOULD POINT THE TRAIN OF VORT CENTERS
TOPPING THE RIDGE IN A SORT OF RING-OF-FIRE IN OUR DIRECTION.
WHETHER OR NOT ANY OF THESE REMNANTS BRINGS ANYTHING OTHER THAN MORE
DEBRIS CLOUDS IS THE BIG QUESTION. THERE IS A GENERAL CONSENSUS
AMONG THE MODELS THAT MOST OF THE DEEP CONVECTION WILL MOVE DOWN
ACROSS VA AND THEN THE ERN HALF OF NC TODAY. HOWEVER...AM NOT
WILLING TO RULE OUT SOME CONVECTIVE DEVELOPMENT ON THE SW FLANK THAT
WOULD MOVE DOWN OVER THE MTNS AND NRN FOOTHILLS LATE IN THE DAY OR
THIS EVENING...SIMILAR TO WHAT IS SEEN IN THE SPC 4KM WRF. SO...THE
FCST WILL FEATURE A CHANCE POP MAINLY OVER THE MTNS AND ALONG/N OF
I-40 THROUGH THE AFTERNOON AND INTO THE LATE EVE. ADDITIONAL STORMS
COULD ALSO ARRIVE ON OUR NRN BORDER THROUGH EARLY SATURDAY MORNING.
THAT LEAVES MOST OF THE UPSTATE AND NE GEORGIA WITH AT BEST ISOLATED
COVERAGE. TEMPS WILL BE HOT THIS AFTERNOON...BUT PROBABLY NOT HOT
ENOUGH FOR A HEAT ADVISORY.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
AS OF 245 AM FRIDAY...SHORT RANGE GUIDANCE INDICATES THAT A H592
RIDGE WILL REMAIN CENTERED ACROSS THE LOWER MISSISSIPPI RIVER VALLEY
AS A TROF RIPPLES ACROSS THE ATLANTIC COAST. THE MID LEVEL PATTERN
MAY PLACE THE CWA WITHIN THE PATH OF NW TO SE TRACKING MCS SAT PM.
FORECAST SOUNDINGS INDICATE THAT A WEAK INVERSION WILL EXIST AROUND
H7...WITH CAPES RANGING FROM 1500 J/KG ACROSS THE MTNS TO SUB 500
J/KG EAST. THE PATTERN AND GUIDANCE WOULD FAVOR THE MTNS FOR
SHRA/TSRA...WITH WEAKENING EXPECTED EAST OF THE MTNS AS STORM
ENCOUNTER LIMITED INSTABILITY AND DOWN SLOPE FLOW. I WILL INDICATE A
40 POPS ACROSS THE MTNS WITH 30 POP EAST SAT AFTERNOON AND EVENING.
HIGH TEMPERATURE ARE FORECAST TO RANGE AROUND 5 DEGREES ABOVE NORMAL.

SATURDAY NIGHT...NAM AND GFS INDICATE THAT A BACKDOOR COLD FRONT
WILL SLIDE NE TO SW...REACHING THE NC PIEDMONT AND FOOTHILLS AROUND
MIDNIGHT. SCT SHRA AND POSSIBLY TSRA WILL DEVELOP ALONG AND AHEAD OF
THE BACKDOOR COLD FRONT. I WILL MAINTAIN CHC POPS ACROSS THE CWA
SATURDAY NIGHT. THE NAM IS AGGRESSIVE WITH ADVECTING DRIER AIR FROM
THE NE DURING THE DAYLIGHT HOURS ON SUNDAY. HOWEVER...THE GFS AND
ECMWF ARE SLOWER WITH THE ARRIVAL OF DRIER AIR...RESULTING IN
LINGERING WEAK CONVECTION...I WILL LINGER CHC POPS. TEMPERATURES
UNDER CLOUD COVER AND NE LLVL WINDS WILL LIKELY RANGE AROUND 5
DEGREES BELOW NORMAL.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...MONDAY THROUGH WEDNESDAY...MEDIUM RANGE GUIDANCE
INDICATES THAT MID LEVEL RIDGING AND SFC HIGH PRESSURE WILL BUILD
ACROSS THE CWA. GFS FORECAST SOUNDING THROUGH THE PERIOD SHOWS A
PERSISTENT LAYER OF DRY AIR...YIELDING LITTLE TO NO INSTABILITY. I
WILL FORECAST A DRY PERIOD ACROSS THE CWA...WITH ISO CONVECTION
LIMITED TO THE MTNS. HIGH TEMPERATURES ON MON WILL RANGE AROUND 5
DEGREES BELOW NORMAL...RECOVERING TO NEARLY NORMAL BY WEDNESDAY. ON
THURSDAY...MODELS TIME A COLD FRONT ACROSS THE SOUTHERN APPALACHIANS
DURING THE DAYLIGHT HOURS. RETURN FLOW SHOULD RESULT IN BUILD
MOISTURE AND LLVL DEWPOINTS. I WILL FORECAST CHC POPS FOR SHRA/TSRA
WITH NEAR NORMAL TEMPERATURES.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
AT KCLT...VFR THROUGH THE PERIOD. MID/HIGH LEVEL CONVECTIVE DEBRIS
EXPECTED THROUGH MOST OF FRIDAY MORNING...WITH A LIGHT WNW WIND.
EXPECT WIND TO COME AROUND TO SOMETHING EVEN MORE NW FRIDAY
AFTERNOON WITH A FEW HIGH BASED CU DEVELOPING. THERE SHOULD BE A FEW
TSRA AROUND...BUT THE BETTER CHANCES WILL BE OVER THE HIGHER
TERRAIN.

ELSEWHERE...THE GUIDANCE ONCE AGAIN HITS THE FOG HARD OVER THE NC
MOUNTAINS. PREFER TO TAKE MORE OF A WAIT AND SEE APPROACH BECAUSE
THIS LOOKS LIKE ANOTHER OVERFORECAST AT THIS TIME. WILL KEEP AN MVFR
AT KAVL FOR FOG...BUT THAT IS NOT CERTAIN. WIND SHOULD BE W OR NW
THROUGH THE PERIOD. THE MTNS AND FOOTHILLS HAVE THE BEST CHC FOR
PRECIP...SO THE PROB30 WILL BE KEPT AT KAND/KHKY.

OUTLOOK...A SIMILAR PATTERN IS EXPECTED FRI NIGHT...WITH MAINLY FAR
NRN TIER SCT CONVECTION POSSIBLE. A BACKDOOR COLD FRONT WILL SAG
INTO THE REGION THROUGH THE WEEKEND...WITH CHANCES OF RESTRICTIONS
INCREASING AT KHKY AND KAVL. A MORE DIURNAL PATTERN OF EARLY MORNING
LOW CLOUDS/FOG AND SCATTERED AFTN TSTMS MAY RETURN EARLY NEXT WEEK.

CONFIDENCE TABLE...

            07-13Z        13-19Z        19-01Z        01-07Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  94%     HIGH  95%     HIGH 100%     HIGH 100%
KHKY       HIGH  91%     HIGH  95%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH  91%     HIGH  95%     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...NED
NEAR TERM...PM
SHORT TERM...NED
LONG TERM...NED
AVIATION...PM






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