« Back
NWS Peachtree City, Ga » Text Product » GSP Area Forecast Discussion


Printer-friendly Version
Current Version              Previous Versions:   1  2  3  4  5  6  7  8  9  

Area Forecast Discussion

487
FXUS62 KGSP 170228
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1028 PM EDT TUE SEP 16 2014

.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA TODAY...ENHANCING CHANCES FOR
SHOWERS AND THUNDERSTORMS THROUGH TONIGHT. IN ITS WAKE...SEASONABLY
COOL AIR WILL SPILL INTO THE REGION WEDNESDAY. THE COOL CONDITIONS
AND MOSTLY DRY WEATHER WILL LAST INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
1000 PM ED UPDATE...THE COMBINATION OF +1000J/KG MUCAPE AND LLVL
CONVERGENCE IN THE VICINITY OF THE SURFACE BOUNDARY OVER THE
CHARLOTTE METRO AREA AND UNION NC WAS KEEPING THE CONVECTION
ONGOING. LATEST RADAR TREND SHOWS THE AXIS OF THE HEAVIEST RAIN IS
SLOWLY SHIFTING SOUTH. THEREFORE...HAVE INCREASED POPS FOR THE
AFFECTING AREAS THRU MIDNIGHT. OTHERWISE...THE FRONT SHOULD CONTINUE
TO PUSH SOUTH OVERNIGHT SETTING UP A COOL AIR WEDGE OVER THE
FORECAST AREA. THIS WILL YIELD A RATHER QUIET CONDITIONS OVERNIGHT
WITH PREVAILING NE WINDS AND CONSIDERABLE LLVL CLOUDINESS.

745 PM EDT UPDATE...SCATTERED CONVECTION WILL CONTINUE TO AFFECT
PARTS OF THE WESTERN NC PIEDMONT AND SOUTHERN UPSTATE SC OVER THE
NEXT SEVERAL HOURS. LATEST CONVECTION ALLOWING MODELS SUGGEST THAT
THE CONVECTION SHOULD DIMINISH AFTER MIDNIGHT...SO POPS WERE UPDATED
TO RAMP DOWN ACCORDINGLY. OTHERWISE...EXPECT A COOL AIR WEDGE TO SET
UP ACROSS THE FORECAST AREA OVERNIGHT...LEADING TO CONSIDERABLE LOW
CLOUDS WITH PATCHY FOG. HENCE...HAVE INCREASED THE SKY COVER AND
MENTIONED PATCHY FOG FOR MOST LOCATIONS THRU SUNRISE.

AS OF 450 PM EDT TUESDAY...CONVECTION CONTINUES TO EXPAND THIS
AFTERNOON ACROSS THE REGION AMONGST A MODERATELY UNSTABLE AIRMASS.
LATEST SPC MESOANALYSIS INDICATES UPWARDS OF 2000J/KG SBCAPE PRESENT
ALONG THE I85 CORRIDOR WITH A DISTINCT MAXIMA ACROSS PORTIONS OF THE
SC UPSTATE. THE ENVIRONMENT WILL REMAIN FAVORABLE FOR DAMAGING WINDS
AND POTENTIALLY SEVERE HAIL THROUGH THE AFTERNOON. CURRENT FORECAST
REMAINS ON TRACK THEREFORE NO CHANGES WERE MADE.

PREVIOUS DISCUSSION...

AS OF 240 PM EDT TUESDAY...LATEST SPC MESOANALYSIS INDICATES A
RATHER LARGE AND INCREASINGLY UNSTABLE AIRMASS ACROSS MUCH OF THE
LOWER TERRAIN OF NORTHEAST GA AND THE WESTERN CAROLINAS.  CONVECTION
INITIATING ACROSS THE FOOTHILLS OF THE BLUE RIDGE INTO THE NC
PIEDMONT WILL CONTINUE THROUGH THE AFTERNOON WITH COVERAGE EXPANDING
SOUTHWARD INTO THE UPSTATE OF SC AND NORTHEAST GA.  SOUNDINGS ACROSS
THESE ZONES DO INDICATE DECENT CAPE THROUGH THE LOWEST 400MB WITH
INCREASING SHEAR AHEAD OF AN APPROACHING WEAK UPPER SHORT WAVE.
THUS...AFTERNOON FORECAST FEATURES ISOLATED/SCATTERED POPS WITH A
FEW STRONG THUNDERSTORMS POSSIBLE WITH GUSTY WINDS AND CLOUD TO
GROUND LIGHTNING BEING THE PRIMARY THREATS.  OTHERWISE...ASIDE FOR
POSSIBLE/BRIEF REDEVELOPMENT ALONG BACK DOOR FRONTAL
BOUNDARY...EXPECTING CONVECTION TO ERODE BY LATE EVENING AS HEATING
SUBSIDES AND DRY AIR ADVECTS IN.  GUIDANCE DOES INDICATE THAT THE
BOUNDARY ITSELF WILL BE RATHER SLOW TO PUSH THROUGH THE PIEDMONT
REGIONS OF NC/SC OVERNIGHT LEADING TO CONTINUED CLOUDINESS AND LOW
END PRECIPITATION CHANCES INTO MORNING ALONG AND EAST OF I77.

FOR WEDNESDAY...HIGH PRESSURE SLIDING EAST THROUGH THE OHIO VALLEY
WILL CONTINUE TO DOMINATE THE WEATHER PATTERN LEADING TO PREVAILING
NORTHERLY FLOW AND WELL BELOW NORMAL TEMPERATURES AMIDST MOSTLY
SUNNY SKIES.  FORECAST WILL REMAIN DRY FOR MOST OF THE REGION WITH
ONLY ISOLATED SHOWERS POSSIBLE ACROSS THE EAST WHERE LINGERING
FRONTAL MOISTURE RESIDES...AND ALSO ALONG PORTIONS OF THE WESTERN NC
MOUNTAINS WHERE UPSLOPE FLOW COULD INDUCE A FEW SHOWERS.  NOT
EXPECTING ANY DEEP CONVECTION ON TUESDAY AS DRIER/COOLER BOUNDARY
LAYER WILL INHIBIT INSTABILITY THROUGHOUT THE DAY.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
AS OF 245 PM TUE...LONG WAVE TROF REMAINS OVER THE ERN CONUS THRU
THE PERIOD...ALTHOUGH THE AXIS DOES MOVE OFF SHORE BY THE END OF THE
PERIOD. A SERIES OF WEAK SHORT WAVES MOVE ACROSS THE AREA THRU THE
TROF. HOWEVER...THERE IS LITTLE DEEP MOISTURE AND FORCING ASSOCIATED
WITH THESE SYSTEMS. THERE IS QUITE A BIT OF LOW LEVEL MOISTURE AND
SOME MECHANICAL FORCING IN THE LOW LEVEL ELY FLOW WITH SFC HIGH
PRESSURE REMAINING RIDGED INTO THE AREA FROM THE NORTH.
HOWEVER...FORECAST SOUNDINGS SHOW THE ATMOS REMAINS CAPPED THRU THE
PERIOD WITH WARM MID LEVEL TEMPS. THEREFORE...HAVE GONE WITH A DRY
FORECAST THRU THE PERIOD...EXCEPT FOR SOME LINGERING CONVECTION WED
EVENING. THERE SHUD BE QUITE A BIT OF NIGHT TIME CLOUDS WITH THE LOW
LEVEL MOISTURE AND ELY FLOW...WITH SOME CLEARING DURING THE DAY.
TEMPS WILL BE AROUND 5 DEGREES BELOW NORMAL.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 300 PM TUE...UPPER TROF BRIEFLY BUILDS INTO THE AREA EARLY IN
THE MEDIUM RANGE AS AN UPPER TROF MOVES OFF SHORE. ANOTHER UPPER
TROF BUILDS OVER THE ERN CONUS ON MON AND REMAINS ON TUE. AT THE
SFC...HIGH PRESSURE REMAINS RIDGED INTO THE AREA FROM THE NORTH WITH
A MODERATING AIR MASS UNTIL A COLD FRONT CROSSES THE AREA MONDAY.
HIGH PRESSURE BEGINS TO BUILD IN AS THE FRONT SLOWLY MOVES EAST ON
TUE. EXPECT A DRY FCST FRI AND SAT...WITH ONLY A SLIGHT CHC OF
PRECIP MOVING IN ACROSS THE WEST AHEAD OF THE FRONT ON SUN. MTNS
WILL SEE THE BEST CHC OF PRECIP MON WHERE MOISTURE AND FORCING ARE
HIGHEST. PRECIP CHC DIMINISHES TO SLIGHT CHC FOR TUE AND MAINLY
OUTSIDE OF THE MTNS IN THE LINGERING MOISTURE BEHIND THE SLOW MOVING
FRONT. BELOW NORMAL TEMPS RISE TO A LITTLE ABOVE NORMAL AHEAD OF THE
FRONT...THEN DROP A LITTLE BELOW NORMAL BEHIND THE FRONT ON TUE.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...SCATTERED CONVECTION OVER THE WESTERN NC PIEDMONT WILL
AFFECT THE TERMINAL AT LEAST THROUGH 02Z PER LATEST RADAR TRENDS AND
CONVECTION ALLOWING MODELS. HENCE...HAVE MENTIONED TEMPO FOR TSRA
BETWEEN 00Z AND 02Z. LATEST GUIDANCE CONTINUES TO SUGGEST MVFR
CIGS/VISBY OVERNIGHT AS A COOL AIR WEDGE SETS UP OVER THE AREA. THE
CONDITIONS WILL THEN IMPROVE TO VFR AFTER SUNRISE. THE WEDGE WILL
REMAIN IN PLACE THRU WED NIGHT...LEADING TO CONSIDERABLE LMVFR
CLOUDINESS WITH PERSISTENT NE WINDS.

ELSEWHERE...SCATTERED CONVECTION WILL CONTINUE TO AFFECT PARTS OF
THE WESTERN NC FOOTHILLS/PIEDMONT AND SOUTHERN UPSTATE SC OVER THE
NEXT SEVERAL HOURS PER LATEST RADAR TRENDS AND CONVECTION ALLOWING
MODELS. LATEST GUIDANCE CONTINUES TO SUGGEST THAT A COOL AIR WEDGE
WILL DEVELOP OVERNIGHT...YIELDING MVFR CIGS/VISBY ACROSS MUCH OF THE
REGION WITH POSSIBLE IFR CIGS/VISBY IN PARTS OF THE NC MTNS/VALLEYS.
HENCE...HAVE GONE WITH TEMPO FOR IFR CIGS/VISBY AT KAVL BETWEEN
08Z-12Z. OTHERWISE...CONDITIONS SHOULD IMPROVE TO IFR AFTER SUNRISE.
WITH THE WEDGE REMAINING IN PLACE...EXPECT CONSIDERABLE LVFR CLOUDS
AND LIGHT NE WINDS TO PERSIST AT LEAST THRU WED AFTERNOON.

OUTLOOK...ALTHOUGH THE CHANCES FOR DIURNAL CONVECTION WILL GREATLY
DIMINISH AFTER WEDNESDAY...THE POTENTIAL FOR LATE NIGHT/MORNING
FOG/STRATUS WILL PERSIST INTO LATE WEEK...ESP IN THE MTN VALLEYS.
CONDITIONS MAY FINALLY DRY OUT FOR THE WEEKEND.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-02Z
KCLT       MED   69%     LOW   56%     HIGH  94%     HIGH 100%
KGSP       MED   63%     MED   69%     HIGH 100%     HIGH 100%
KAVL       MED   71%     HIGH  85%     MED   65%     LOW   58%
KHKY       MED   71%     MED   66%     MED   72%     LOW   58%
KGMU       LOW   57%     LOW   41%     HIGH 100%     HIGH 100%
KAND       MED   63%     LOW   57%     HIGH  96%     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...CDG
NEAR TERM...CDG/JOH
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...JOH






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.