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Area Forecast Discussion

109
FXUS62 KGSP 201755
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1055 AM EDT MON OCT 20 2014

.SYNOPSIS...
DRY CANADIAN HIGH PRESSURE WILL PERSIST ACROSS THE REGION
TODAY...WITH A WEAK FRONTAL SYSTEM MOVING INTO THE NORTH CAROLINA
MOUNTAINS EARLY TUESDAY. DRY AND SEASONAL HIGH PRESSURE WILL BUILD
BACK IN BEHIND AN UPPER LEVEL TROF WEDNESDAY AND REMAIN ACROSS THE
AREA THROUGH THE WORK WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
CU FIELD DEVELOPING FROM PARTS OF THE SOUTHERN UPSTATE INTO THE
WESTERN PIEDMONT OF NC. OTHERWISE SOME PATCHY CI HERE AND THERE.
WE DO NOT SEE MUCH NEED FOR ANY SIGNIFICANT ADJUSTEMENTS IN THE
FORECAST OTHER TO MENTION HAVE A BIT MORE CLOUDS WHERE THE CU IS
BECOMING MORE OPAQUE. OTHERWISE TEMPERARATURES STILL ON TARGET.

MID MORNING DISUSSION...
OUR MID MORNING UPDATE WAS TO ADD FOG FOR A FEW HOURS IN THE REST OF
THE WESTERN NC RIVER VALLEYS WHERE CIRRUS CLOUDS EXITING AND FOG WAS
ABLE TO DEVELOP. MOST OF THAT FOG IS BURNING OFF...WITH THE LAST IN
THE LITTLE TENNESSEE RIVER VALLEY...AND THAT SHOULD BE GONE SOON.
OTHERWISE THE REMAINDER OF THE FORECAST IS IN GOOD SHAPE...WITH OUR
DIURNAL TEMPERATURES AND DEWPOINTS FOLLOWING A DECENT TREND.

REMAINDER OF PREVIOUS DISCUSSION...
MORNING UPDATE...WITH THICKER CI CROSSING OVERHEAD...TEMPS AND TD/S
ARE REMAINING ABOVE FR LEVELS ACROSS THE NC MTNS...BUT ISOL AREAS
COULD SEE LIGHT FR THROUGH DAYBREAK. NO SIGFNT CHANGES WERE NEEDED
TO THE GRIDS.

430 AM EDT UPDATE...PASSING BKN/OVC CI FIELD CONTINUES ACROSS MAINLY
THE NRN ZONES THIS MORNING. EVEN WITH CALM CONDS...TEMPS HAVE
REMAINED A COUPLE DEGREES F ABOVE THE FCST CURVE ACROSS THE FB
VALLEY AND OVER THE NC PIEDMONT AND UPSTATE. THUS...THE HR/LY TEMP
GRIDS WERE ADJ UPWARD A BIT OVER THE NEXT FEW HRS. THE THREAT OF
WIDESPREAD FR FORMATION ACROSS THE NRN MTNS LOOKS MINIMAL PER THE
LATEST MESONET T/TD DATA...HOWEVER PATCHY DEVELOPMENT IS STILL
POSSIBLE BEFORE AND THRU SUNRISE.

AS OF 245 AM EDT...SURFACE HIGH PRESSURE WILL CONTINUE TO DOMINATE
THE WX PATTERN THIS MORNING AND THROUGH MUCH OF THE NEAR TERM. THIS
WILL MAINTAIN FAIRLY WEAK WINDS WITH NOMINAL MIXING IN WEAK LLVL
FLOW. UPPER LEVEL CLOUDS ASSOCIATED WITH A PASSING TROF AXIS WILL
DIMINISH THROUGHOUT THE DAY...YET FEW/SCT CI WILL LINGER WITH FEW/SCT
FAIR WX CU PROBABLE AS WELL. MAX TEMPS WILL BE CLOSE TO NORMAL AND
RIGHT IN LINE WITH EXPECTED LLVL THICKNESS VALUES.

WITH THE SFC HIGH SHIFTING OFFSHORE...THE INCREASE IN SW/LY
TEMP/MOIST FLUX MON WILL MAINTAIN HIGHER MINS OVERNIGHT AS WELL.
THIS WILL OFFSET MOST FG AND FR THREATS...HOWEVER SOUNDINGS AND
MOS GUIDANCE STILL INDICATE A GOOD PROB FOR LOW VSBY ACROSS THE
FRENCH BROAD AND LITTLE TN VALLEYS BEFORE DAYBREAK. AN INCREASE IN
STCU WILL OCCUR ACROSS THE NC MTN SPINE AND NRN MTNS OVERNIGHT AS A
CLIPPER SYSTEM DIVES OUT OF THE GLAKE REGION AND THIS SHOULD BE ENUF
TO DIFFUSE VSBY CONCERNS OVER THESE AREAS. THERE WILL BE ENOUGH MECH
LIFT AND SOME ULVL DYNAMICAL AIDE TO ALLOW FOR -SHRA AND SPRINKLES
WHICH IS COVERED WITH ISOL POPS MAINLY ACROSS THE NRN FOUR NC MTN
COUNTIES. MINS MON NIGHT WILL BE WARMER THAN THIS MORNINGS LOWS BY A
COUPLE CATS OR RIGHT AROUND NORMAL.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 305 AM EDT MONDAY...ANOTHER IN A SERIES OF POTENT SHORT WAVE
TROUGHS WILL DIG STRONGLY OUT OF THE GREAT LAKES REGION...TOWARD THE
SOUTHERN APPALACHIANS AND MID-ATLANTIC EARLY IN THE SHORT TERM
PERIOD. THIS WILL INTRODUCE ANOTHER SURGE OF COOL AIR INTO OUR AREA
LATE TUE INTO TUE NIGHT. THE SERIES OF WAVES WILL CARVE OUT AN UPPER
LOW OVER THE MID-ATLANTIC/NORTHEAST THAT WILL RESULT IN A SOMEWHAT
PROTRACTED PERIOD OF NW FLOW ACROSS THE CAROLINAS/NORTH GEORGIA INTO
LATE WEEK. A PERIOD OF NW FLOW RAIN SHOWERS WILL BE POSSIBLE...
MAINLY TUE NIGHT AS UPSLOPE MOISTURE DEEPENS BRIEFLY WITH THE
PASSAGE OF THE UPPER WAVE. HOWEVER...EVEN THEN TENN BORDER POPS
SHOULD NOT EXCEED 30 PERCENT OR SO. MOISTURE WILL BECOME MORE
SHALLOW BY EARLY WED...BUT STILL EXPECT PLENTY OF LINGERING CLOUD
COVER TO PERSIST NEAR THE TENN BORDER THROUGH THE END OF THE PERIOD.
MEANWHILE...CLASSIC COOL/MOSTLY CLEAR AUTUMN WEATHER WILL PERSIST
SOUTHEAST OF THE BLUE RIDGE... WITH NEAR NORMAL TEMPS ON TUESDAY
GIVING WAY TO WEATHER THAT WILL BE 5-10 DEGREES BELOW CLIMO BY
WEDNESDAY. DESPITE THIS...CURRENT INDICATIONS ARE THAT CLOUDS AND/OR
WIND WILL PRECLUDE MUCH OF A FROST FREEZE CONCERN IN THE MTNS...
EXCEPT PERHAPS IN THE SHELTERED VALLEYS OF THE SOUTHWEST MTNS (WHERE
THE FROST/FREEZE PROGRAM HAS ALREADY ENDED FOR THE SEASON).

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 315 AM MONDAY...THE PATTERN WILL REMAIN TYPICALLY INACTIVE
THROUGH THE MEDIUM RANGE...AS A MEAN LONG WAVE TROUGH WILL GENERALLY
BE MAINTAINED NEAR THE EAST COAST THROUGH THE PERIOD. TEMPS WILL
MODIFY CLOSER TO CLIMO BY THE WEEKEND...AS HEIGHTS RISE DOWNSTREAM
OF DAMPENING SHORT WAVE RIDGE. A CONSENSUS OF THE LATEST GLOBAL
MODEL GUIDANCE WOULD SUGGEST PASSAGE OF ANOTHER STRONG SHORT WAVE
TROUGH OVER THE WEEKEND...WHICH COULD BRING SMALL CHANCES FOR
MOUNTAIN SHOWERS AND COOL US DOWN AGAIN BY THE END OF THE PERIOD.

&&

.AVIATION /18Z MONDAY THROUGH FRIDAY/...
AT KCLT AND ELSEWHERE...VFR FLIGHT CONDITIONS THROUGHOUT THE TAF
PERIOD. HIGH PRESSUE CONTINUES TO MOVE EAST AND RETURN FLOW WAS
HELPING SOME SCT CU TO DEVELOP THIS AFTERNOON. THIS MAY MAKE A RUN
AT THE CLT AIRFIELD...BUT ABOVE MVFR CONDITIONS. AHEAD OF THE NEXT
APPROACHING FRONT...THE MODELS WERE ADVERTISING A BAND OF AC/CI
ZIPPING ACROSS THE REGION TONIGHT. WE HAVE FOLLOWED THIS TREND AND
INSERTED INTO SAID FORECAST.

WINDS SHOULD BE SOUTHERLY...AND WE BUMPED THEM UP A NOTCH...BASED ON
SOUNDING DATA. THOSE SHOULD RELAX AT SUNDOWN.

FOLLOWING THE AC/CI MOVING THROUGH TONIGHT...AND BEFORE THE LOW
CLOUDS CAN START IN THE CAA PATTERN WITH THE NEXT FRONT...THERE MAY
BE A WINDOW OF OPPORTUNITY FOR FOG IN THE NC MOUNTAIN VALLEYS/THE NW
UPSTATE OF SC/AND NORTHEAST GEORGIA.

OUTLOOK...A ROUND OF GUSTY NW WINDS AND MOUNTAIN STRATOCU WILL BE
POSSIBLE BEHIND A MOSTLY DRY COLD FRONT LATE TUE INTO EARLY WED.
OTHERWISE...VFR CONDITIONS SHOULD PREDOMINATE INTO LATE WEEK.

CONFIDENCE TABLE...

            10-16Z        16-22Z        22-04Z        04-10Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  94%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH  89%     HIGH  99%     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...SBK
NEAR TERM...SBK/TS
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...SBK












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