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Area Forecast Discussion

304
FXUS62 KGSP 051806
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
106 PM EST THU MAR 5 2015

.SYNOPSIS...
A MOIST COLD FRONT WILL SLOWLY CROSS THE REGION FROM THE NORTHWEST
TODAY...BEFORE COOL AND DRY HIGH PRESSURE BUILDS IN FRIDAY AND
MODIFIES WARMER THROUGH THE WEEKEND. EXPECT A COUPLE OF LOW PRESSURE
SYSTEMS TO DEVELOP OUT OF THE GULF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 100 PM...UPDATED THE TEMPS/WINDS/WX AGAIN TO MATCH UP WITH
TIMING OF THE FRONT...AS IT SLOWLY WORKS SOUTHWARD THRU THE CWFA.
HAS CROSSED THE NC/SC BORDER...AND WILL CONTINUE TO PUSH THRU THE
REST OF THE AREA THIS AFTN. PRECIP IS NEAR CATEGORICAL FOR MOST OF
THE AREA ON NORTH SIDE OF FRONT. THERE IS ALSO QUASI-LINEAR
CONVECTIVE SEGMENT GOING THRU THE EASTERN UPSTATE AND SOUTHERN NC
PIEDMONT. GUSTY WINDS WITH THIS FEATURE AND ALSO JUST BEHIND THE SFC
FRONT ITSELF WILL CONTINUE FOR THE NEXT COUPLE HOURS IN THE
SOUTHEAST CORNER OF THE CWFA.

TO THE WEST...TEMPS HOVERING IN THE MID-UPR 30S ALONG THE TN
LINE...WITH NO ISSUES BEING REPORTED SO FAR. WILL ADDRESS ANY
NEEDED CHANGES TO THE WINTER WX ADV WITH THE NEXT UPDATE.

AS OF 900 AM...SFC FRONT TRYING TO PUSH OFF THE BLUE RIDGE THIS
MORNING. THERE ARE SIGNS ITS FINALLY GOING TO START ITS TREK ACRS
THE FOOTHILLS AND PIEDMONT...AS METARS SHOWING WINDSHIFT TO NW ALONG
I-40. MEANWHILE...TEMPS ARE STILL UP IN THE MID 60S ACRS MOST OF THE
PIEDMONT...WITH GUSTY SW WINDS AND SPOTTY -RA. THE LATEST LAPS CAPE
SHOWS GENERALLY 50-100 J/KG OF SBCAPE ACRS THE UPR SAVANNAH VALLEY
TO THE GREENVILLE AREA. SO CANNOT RULE OUT AN EMBEDDED TSTM ACRS THE
PIEDMONT TODAY...BUT SEVERE THREAT LOOKS VERY LOW. I UPDATED THE
TEMPS/WX TO MATCH UP WITH THE LATEST TIMING OF THE FRONT. STILL NOT
SEEING ANY SUB-FREEZING TEMPS IN ANY OF OBS WITHIN THE CWFA.
HOWEVER...THE TEMPS IN THE MTNS NEAR THE TN LINE HAVE BEEN INCHING
DOWN INTO THE 30S. SO WHILE BACKING OFF TIMING OF PRECIP TYPE
CHANGES IN THE HIGH TERRAIN...STILL EXPECT SOME FREEZING RAIN THEN
SLEET/SNOW MIX FROM THE PEAKS DOWN THIS AFTN. THE VALLEYS BELOW 3500
FT WILL LIKELY STAY RAIN UNTIL LATE AFTN. TIMING OF PRECIP CUTTING
OFF THIS EVENING STILL LOOKS ON TRACK. WITH ALL THAT SAID...STILL
HAVE ENUF PATCHY ICE AND SNOW ACCUMS TO KEEP THE WINTER WX ADV AS IS
WITH THIS UPDATE.

AS OF 600 AM...SFC FRONT OOZING OUT OF THE BLUE RIDGE...AND WITH
RAIN CVRG INCREASING...SFC PRESSURE RISES AND A NE WIND SHOULD
DEVELOP THIS MORNING...INITIALLY ACRS THE NC FTHLS/PIEDMONT. BASED
ON THIS...WARM CONDITIONS SHOULD LINGER ALL MORNING ACRS THE UPSTATE
AND NE GA. IT DOES NOT SEEM TO BE AOB FREEZING ANYWHERE ACRS THE NC
MTNS JUST YET...BUT SLOW COOLING WILL CONTINUE TO EVOLVE FROM THE
TENN BORDER AND HIGHER ELEVATIONS...SLOWLY EXPANDING THE CVRG OF
FREEZING RAIN THROUGH MIDDAY.

AS OF 230 AM...WAVY COLD FRONT PASSED THROUGH KAVL SHORTLY AFTER 06
UTC AND WILL PROBABLY TAKE UNTIL AT LEAST MIDDAY TO CLEAR THE
BALANCE OF THE CWFA. STILL EXPECTING TO SEE WIDESPREAD DEVELOPMENT
OF PCPN IN THE WAKE OF THE FRONT IN A CLASSIC ANAFRONT ORIENTATION.

ADVANCEMENT OF SFC FREEZING LINE STILL UPSTREAM OF THE NC MOUNTAINS
AND ANYTHING MORE THEN LIGHT ICING IN THE HIGHEST ELEVATIONS IS
DOUBTFUL BY DAYBREAK. BUT AS THE MORNING WEARS ON...SUB-FREEZING
SFC TEMPS WILL WORK STEADILY SE INTO THE NC MTNS AND LOWER IN
ELEVATION. WITH MTN FCST SNDGS LINGERING PROMINENT WARM NOSE THROUGH
18Z...ANY WINTRY PCPN OTHER THAN FREEZING RAIN IS DOUBTFUL.

WITH CRITICAL MID-LVL THICKNESS VALUES ENCROACHING THIS AFTERNOON
THE CHANCES FOR MAINLY HIGHER ELEVATIONS TO PICK UP A LIGHT
ACCUMULATION OF SNOW AND/OR SLEET BECOMES MORE LIKELY.

WILL BANK ON THE BULK OF THE PCPN SHIELD TO CLEAR THE MTNS BY
SUNSET AND THE REST OF THE CWFA...MID-EVENING AT THE LATEST.

EXPECT A MORNING/NON-DIURNAL HIGH TEMPS FOR JUST ABOUT EVERYONE
TODAY WITHIN THE LLVL CAA REGIME AND PCPN.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 1230 PM EST THURSDAY...THE SHORT RANGE PART OF THE FORECAST
APPEARS TO BE RATHER QUIET...WITH THE UPPER PATTERN SLOWLY
DEAMPLIFYING. THE PATTERN WILL SUPPORT WEAKENING HIGH PRESSURE
ACROSS MOST OF THE SOUTHEAST THROUGH THE BETTER PART OF THE
WEEKEND...WITH TEMPS REBOUNDING CLOSER TO NORMAL. ONCE WE GET TO
SUNDAY...THE CONFLUENT AREA OF THE SPLIT UPPER FLOW WILL MIGRATE EWD
OVER THE MID-ATLANTIC AND CAROLINAS. THIS DEVELOPMENT WILL MAKE THE
TIMING OF THE NEXT SYSTEM...IN THE SRN BRANCH OF THE SPLIT FLOW...A
BIT MORE PROBLEMATIC. FOR NOW...HAVE ELECTED TO KEEP THE DEVELOPMENT
OF PRECIP OFF TO THE WEST THROUGH THE END OF DAYLIGHT ON SUNDAY...
BUT THIS COULD EASILY HAVE TO BE MOVED UP.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 220 AM EST THURSDAY...THE EXT RANGE WILL BEGIN WITH A RATHER
NICE DAY ON SUN. DEVELOPING UPPER CONFLUENCE OFF THE ATL COAST WILL
FORCE A SFC HIGH PRESSURE AREA EAST ACROSS THE FA AND KEEP WINDS
LIGHT AND S/LY. MEANWHILE...MOISTURE LEVELS WILL REMAIN LOW EXCEPT
FOR SOME CI INCREASING FROM THE WEST. MAX TEMPS WILL BE RIGHT AROUND
OR A LITTLE ABOVE NORMAL.

THE FCST BECOMES MORE UNCERTAIN THROUGH THE WORK WEEK AS THE MODELS
HAVE VARYING IDEAS WITH THE SPLIT FLOW AND PLACEMENT OF THE H3 JET
CORE. THE 00Z ECMWF IS MORE AGGRESSIVE WITH BRINGING GOM MOISTURE
OVER THE SE AS IT DEVELOPS CYCLOGENESIS OVER THE NRN GULF IN
RESPONSE TO A BROAD BUT DEEPENING ULVL TROF THRU 12Z TUE. THE GFS ON
THE OTHER HAND...KEEPS DOMINATE HIPRES ANCHORED OVER THE MID ATL AND
A DRY NE/LY FLOW UNDER FLAT RIDGING ALOFT. THE CMC REG SIDES MORE
WITH THE GFS AND THIS WILL BE GIVEN MORE WEIGHT IN THE FCST GRIDS.
THUS...POPS WERE REDUCED MON/TUE TO SLT NORTH AND LOW/END CHANCE
SOUTH.

THERE REMAINS MUCH UNCERTAINTY FOR WED AS THE GFS TAKES THE
LEAD IN DEVELOPING A NORTHWARD MOVING GOM LOW OVER THE DEEP SOUTH
INSTIGATING WIDESPREAD ISENT/WEDGE -SHRA...WHILE THE ECMWF KEEPS A
STATIONARY FRONT AND DEEP MOISTURE FOCUSED SOUTH OF THE FA WITH
MINIMAL PRECIP MAKING IT TO THE SRN ZONES. SO...ONCE AGAIN POPS WERE
LOWERED MOST AREAS WITH NOTHING HIGHER THAN LOW END CHANCE THOUGH
THE DAY. WITH THE NON/ZERO POPS ACROSS THE NC MTNS MON THRU
WED....THERE COULD BE SOME DIURNAL HIGH ELEVATION -SNSH WITH NO
SIGFNT ACCUMS EACH MORNING. TEMPS ARE FCST/D RIGHT AROUND NORMAL
MON/WED...WHICH IS A LITTLE UNDER MOS GUIDANCE DUE TO UNCERTAINTY
WITH THE FLOW AND MOISTURE LEVELS.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AT KCLT...THE FRONT HAS JUST PUSHED THRU KCLT...WITH A
SQUALL/WNDSHFT TO THE NORTH. WINDS WILL REMAIN GUSTY INTO THIS
EVENING...BASED ON TRENDS IN UPSTREAM METARS...GENERALLY 15-20KTS.
CIGS ARE STILL EXPECTED TO DROP TO IFR BEHIND THE FRONT WITHIN THE
NEXT HOUR OR TWO...THEN RETURN TO MVFR BY 01Z...WITH STEADY
IMPROVEMENT LATE EVENING THRU THE OVERNIGHT...AS PRECIP SHIELD MOVES
EAST AND DRY AIR FILTERS IN. VFR CONDITIONS EXPECTED BY DAYBREAK
FRIDAY...WITH LINGERING CIRRUS AND LIGHT NE WINDS THRU 18Z.

ELSEWHERE...THE COLD FRONT HAS PUSHED THRU KGSP...AND WILL BE THRU
KGMU BY 19Z...AND KAND BY 21-22Z. WINDS WILL SHIFT TO N/NE AND WILL
BE GUSTY FOR A FEW HOURS BEHIND THE FRONT. CIGS WILL BE QUITE
VARIABLE...AS LIFT CONTINUES ATOP THE SHALLOW COLD AIR AND DRY AIR
FILTERS IN FROM THE NORTH. PRECIP WILL GRADUALLY TAPER OFF FROM WEST
TO EAST STARTING WITHIN A COUPLE HOURS IN THE NC MTNS...AND EAST OF
KHKY BY EARLY EVENING. CANNOT RULE OUT A FEW FLAKES OF SNOW OR SLEET
PELLETS AT KAVL AND KHKY TOWARD TAIL END OF PRECIP. SKIES WILL
SCATTER OUT EAST OF THE MTNS OVERNIGHT...WITH CIGS OVERALL LIFTING
AS DRY AIR WINS OUT. VFR CONDITIONS WITH WEAKENING N/NE WINDS FRIDAY
MORNING THRU 18Z.

OUTLOOK...VFR CONDITIONS EXPECTED THROUGH THE WEEKEND.

CONFIDENCE TABLE...

            13-19Z        19-01Z        01-07Z        07-12Z
KCLT       HIGH  95%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       MED   74%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       MED   77%     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...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ033-
     048>053-058-059.
SC...NONE.

&&

$$
SYNOPSIS...SBK
NEAR TERM...ARK/CSH
SHORT TERM...JAT
LONG TERM...SBK
AVIATION...ARK



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