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Area Forecast Discussion

320
FXUS62 KGSP 282323
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
723 PM EDT THU APR 28 2016

.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA TONIGHT...WITH HIGH PRESSURE
BUILDING IN FRIDAY INTO SATURDAY. A LOW PRESSURE SYSTEM WILL
APPROACH FROM THE WEST LATE SATURDAY THROUGH SUNDAY NIGHT. THE LOW
WILL LIFT NORTHEAST ALONG THE COAST EARLY NEXT WEEK...BUT LEAVE A
TRAILING COLD FRONT NEAR THE CAROLINA COAST.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 730 PM EDT...HAVE DONE ANOTHER ROUND OF UPDATES TO REDUCE POPS
AGAIN ACROSS THE UPSTATE AND MOUNTAINS. SEVERE THUNDERSTORM WATCH
WILL REMAIN IN EFFECT FOR PORTIONS OF THE NC PIEDMONT AND FOOTHILLS
AS CONVECTION CONTINUES TO BUBBLE ALONG AND JUST AHEAD OF THE
SURFACE LOW ALONG A WEAK CONVERGENCE BOUNDARY. OTHER GRID UPDATES
THIS EVENING ARE MAINLY FOR AVIATION PURPOSES.

OTHERWISE...DRIER DEWPOINTS ARE EXPECTED TO OVERSPREAD THE AREA THIS
EVENING...AS THE SURFACE TROUGH PROGRESSES EAST. THIS SHOULD BRING A
PRETTY QUICK END TO CONVECTIVE CHANCES. THE REMAINDER OF THE NEAR
TERM WILL BE INACTIVE/MOSTLY CLEAR AND QUITE WARM...WITH TEMPS
EXPECTED TO AVERAGE ABOUT 10 DEGREES ABOVE CLIMO THROUGH THE PERIOD.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
AS OF 200 PM EDT THURSDAY...THE SHORT TERM FCST PERIOD INITIALIZES
ON FRIDAY NIGHT AMIDST SHORTWAVE H5 RIDGING OVER THE SOUTHEAST WHILE
AN H5 CYCLONE ROTATES OVER THE SOUTHERN ROCKIES.  AT THE
SURFACE...HIGH PRESSURE OVER THE NORTHEAST WILL BUILD SOUTH ALONG
THE EASTERN SEABOARD ATTEMPTING TO SETUP A SHORT LIVED WEDGE...WHILE
CYCLOGENSIS DEVELOPS/STRENGTHENS OVER THE SOUTHERN PLAINS.  A WARM
FRONT LOOKS TO SPREAD NORTH OVER THE DEEP SOUTH IN ASSOCIATION WITH
THE A FORE MENTIONED SFC CYCLONE INTO SATURDAY WITH CONVECTION
ACTIVATING ALONG IT OVER PORTIONS OF NORTH MS/AL AS WELL AS
WEST/MIDDLE TN.  CLOSER TO HOME...THE WEDGE FRONT MAKES A PUSH INTO
THE REGION ON SATURDAY MORNING BEFORE RETREATING NORTHEAST INTO THE
MID/LATE AFTERNOON HOURS AS THE CONVECTIVELY ACTIVE WARM FRONT
SURGES.

THE UPPER TROF WILL BE ON THE MOVE SUNDAY WITH THE SFC CYCLONE
MOVING NORTHEAST.  THE COLD FRONT ASSOCIATED WITH SAID CYCLONE IS
EXPECTED TO PUSH THROUGH THE OH/TN VALLEYS ON SUNDAY POSSIBLY
YIELDING STRONG/SEVERE CONVECTION THANKS TO AN ABUNDANTLY UNSTABLE
AIRMASS BACKED UP BY AN APPROACHING H5 SHORTWAVE.  AS FOR NORTHEAST
GA AND THE WESTERN CAROLINAS...THE FRONT SHOULD REMAIN TO THE WEST
THROUGH PEAK HEATING HOWEVER SOUNDINGS CONTINUE TO FAVOR SUBSTANTIAL
INSTABILITY ABOUT THE REGION THANKS TO MID 60S DEWPOINTS AND MODEST
LOW/MID LEVEL LAPSE RATES...ALL SUPPORTING SCATTERED SHRA/TSRA.
EXPECTING ANY DEVELOPMENT TO WEAKEN WITH HEATING LOSS INTO THE
EVENING HOURS SUNDAY AS THE FRONT CONTINUES APPROACHING FROM THE
WEST...LIKELY BANKING AGAINST THE WESTERN SLOPES OF THE SOUTHERN
APPS BY MID MORNING MONDAY.

AS FOR THE FCST...POPS WILL INCREASE FROM THE WEST SATURDAY WITH
SLIGHT CHANCES FAVORED OVER THE SW MTNS BY LATE
MORNING...SPREADING/INCREASING NORTH AND EAST INTO THE AFTERNOON
HOURS WHERE MID CHANCES POPS ARE MENTIONED.  FURTHER INCREASES ARE
WARRANTED SATURDAY NIGHT INTO SUNDAY GIVEN THE WARM FROPA WITH THE
VAST MAJORITY OF THE FCST AREA UNDER LIKELY POPS BY DAYBREAK...WHILE
CATEGORICAL LEVELS ARE ANCHORED ALONG THE SOUTHERN BLUE RIDGE
ESCARPMENT.  THESE POP LEVELS WILL PERSIST THROUGH THE DAY BEFORE
GRADUALLY LOWERING INTO THE OVERNIGHT.  REGARDING ANY HAZARDOUS
WX...CANT RULE OUT A STRONG/SEVERE THUNDERSTORM ON SATURDAY ALONG
THE WARM FRONT...WITH BETTER CHANCES BEING ON SUNDAY WHEN
INSTABILITY IS FCST TO BE HIGHER AND DEEPER THROUGH THE COLUMN.
PRECIPITATION TOTALS WILL RANGE FROM 1-2 INCHES OVER THE WEEKEND
WITH LOCALLY HEAVIER AMOUNTS POSSIBLE ASSOCIATED WITH ANY DEEPER
CONVECTION.  TEMPERATURES THROUGH THE PERIOD WILL REMAIN ABOVE
NORMAL.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 100 PM THURSDAY...THE MODEL GUIDANCE CONTINUES TO DISPLAY
SIGFNT DIFFERENCES WITH THE LARGE SCALE PATTERN AND SENSIBLE WX
ACROSS THE SE CONUS BEGINNING MON. THE GFS IS STILL THE DRIER AND
MORE SUPPRESSED MODEL ALLOWING STRONG CANADIAN HIGH PRESSURE TO BUILD
IN AFTER A MOIST FROPA MON...WHILE THE ECMWF HAS A MUCH WETTER SOLN.
THE ECMWF IS PHASING AN UPPER TROF ACROSS THE MIDWEST AND SWINGS IT SE
INDUCING AN INVERTED GOM TROF...WHICH THEN MOVES NE ALONG STATIONARY
FRONT OVER THE CAROLINAS. THE GFS ENS MEANS ALSO SHOW MUCH SPREAD
WITH THE H5 PATTERN BEGINNING MON...BUT IT/S MEANS SUPPORT THE SPLIT
FLOW PATTERN OF THE OP GFS. WITH SO MUCH UNCERTAINTY...WILL MAINTAIN
LOW END POPS GIVING MORE WEIGHT TO CLIMO AND CONSMOS. INSTABILITY
SHUD REMAIN FAIRLY LOW AFTER THE FROPA AND LOWERING SFC TD/S...SO
NOT ANTICIPATING STRONG OR SEVERE ACTIVITY....MAINLY ISOL TO SCT
GENERAL TSTMS. TEMPS COULD BE AN ISSUE AS THE AMOUNT OF DEEP
MOISTURE AND AIR MASS CHANGE/MIX IS STILL UNCLEAR. SO...WILL ALSO
GIVE MOS MORE WEIGHT WITH TEMPS REMAINING A CAT OR SO ABOVE NORMAL
MON...THEN RETURNING TO NORMAL VALUES TUE THROUGH THE PERIOD.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE EXCEPT KHKY...VFR THROUGH THE PERIOD. SW WINDS
WITH LOW-END GUSTS THIS EVENING WILL SUBSIDE OVERNIGHT AND SHIFT NW
WITH THE PASSAGE OF A COLD FRONT. EXPECT LGT/VRB CONDITIONS
OVERNIGHT WITH WINDS GENERALLY OUT OF THE W AROUND 5KT FRIDAY
AFTERNOON. SPECIFICALLY FOR KCLT...HAVE KEPT WINDS JUST N OF W
THROUGH THE PERIOD BUT THIS MAY NEED TO BE ADJUSTED IN LATER
FORECASTS. SHOULD BE SKC FOR THE MOST PART WITH JUST SOME
EARLY-PERIOD VFR CU AND OTHERWISE PATCHY CIRRUS.

FOR KHKY...STILL SOME CONVECTION BUBBLING ACROSS THE FOOTHILLS EARLY
THIS EVENING SO CANNOT TOTALLY RULE OUT A BRIEF SHRA OR POSSIBLY
EVEN TSRA...BUT SAME TRENDS AS OTHER TAFS AFTER 02Z.

OUTLOOK...VFR CONDITIONS SHOULD PERSIST THROUGH FRIDAY NIGHT.
UNSETTLED WEATHER/POSSIBLE RESTRICTIONS/CONVECTION RETURN FROM THE
WEST OVER THE WEEKEND.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH  94%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     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 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULE TAF ISSUANCE FLIGHT RULE CATEGORY.  COMPLET HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK:

WWW.WEATHER.GOV/GSP/AVIATION

&&

.CLIMATE...
RECORDS FOR 04-28

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      86 1986     45 1913     63 1956     29 1928
                1957
   KCLT      90 1943     51 1928     66 1954     36 2005
                                                    2004
                                                    1967
   KGSP      90 1943     54 2013     65 1954     36 1898
                1915
                1914



RECORDS FOR 04-29

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      89 1970     46 1999     63 1956     28 1967
   KCLT      91 1888     48 1999     65 1994     33 1973
                                        1991
                                        1914
   KGSP      91 1917     47 1999     67 1975     32 1992

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...SBK
NEAR TERM...JDL/TDP
SHORT TERM...CDG
LONG TERM...SBK
AVIATION...TDP
CLIMATE...



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