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Area Forecast Discussion

262
FXUS62 KGSP 011741
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
141 PM EDT WED OCT 1 2014

.SYNOPSIS...
DRIER HIGH PRESSURE WILL LINGER OVER THE REGION THROUGH THURSDAY. A
STRONG COLD FRONT WILL THEN ARRIVE FROM THE NORTHWEST ON FRIDAY AND
MOVE OFFSHORE BY EARLY SATURDAY. IN THE FRONTS WAKE...A COOL AND DRY
AIRMASS WILL MOVE BACK OVER THE SOUTHEAST AND REMAIN IN PLACE OVER
THE WEEKEND. ANOTHER COLD FRONT WILL APPROACH THE SOUTHERN
APPALACHIAN REGION FROM THE NORTHWEST ON TUESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF NOON....HAVE BUMPED THE MAZ TEMPS UPWARD A COUPLE DEGREES
BASED ON LATEST TEMP TREND AND LAMP DATA. OTHERWISE...CURRENT
FORECAST LOOKS GOOD.

AS OF 930 AM...CURRENT SATLLEITE PICS SHOW PATCHY HIGH CLOUDS MOVING
FROM WEST TO EAST OVER THE REGION. SOME AC IS NOTED...BUT SOUNDINGS
INDICATE THAT MID LEVEL INVERSION SHOULD CAP OFF ANY DEEP
CONVECTION. THEREFORE...WILL MAINTAIN A DRY FORECAST. MADE ONLY
MINOR ADJUSTMENTS TO TEMP/DP/WIND FIELDS.

AS OF 630 AM...A FEW PATCHES OF FOG ACROSS THE PIEDMONT...BUT THE
VISIBILITY TREND HAS BEEN UPWARD OVER THE LAST BIT...EVEN IN THE MTN
VALLEYS. THE FOG SHOULD DISSIPATE QUICKLY AN HOUR OR TWO AFTER
SUNRISE.

THE NEXT 24 HOURS SHOULD BE RELATIVELY QUIET ACROSS THE WESTERN
CAROLINAS AND NORTHEAST GEORGIA. AN UPPER RIDGE WILL BUILD OVERHEAD
TODAY AND THEN THE AXIS OF THE RIDGE WILL MOVE EASTWARD TONIGHT AS
AN UPPER LOW ALONG THE NEW ENGLAND COAST MOVES FARTHER OFFSHORE. THE
RIDGE WILL SUPPORT WEAK HIGH PRESSURE AT THE SURFACE...AND A FAIRLY
SUBSTANTIVE SUBSIDENCE INVERSION. THE NAM IN PARTICULAR DEVELOPS
WIDELY SCATTERED SHOWERS THIS AFTERNOON ON THE BLUE RIDGE AND MOVES
THEM EAST THIS EVENING...AS THE CAP IS BROKEN OVER PARTS OF THE
PIEDMONT. THIS SEEMS UNLIKELY AND SUSPECT THE NAM SFC DEWPTS ARE TOO
HIGH AS USUAL. THINK THE GFS/ECMWF HAVE THE RIGHT IDEA THAT THE CAP
WILL BE FAR TOO STRONG AND THAT IT WILL REMAIN DRY. HAVE REMOVED ALL
MENTION OF SHOWERS FOR THAT REASON. TEMPS SHOULD BE A DEGREE OR TWO
WARMER THAN TUESDAY. HIGH PRESSURE REMAINS IN CONTROL TONIGHT WITH
PATCHY FOG POSSIBLE AGAIN AROUND DAYBREAK WEDNESDAY.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 3 AM WEDNESDAY...ON THURSDAY...A RIDGE OF SFC HIGH PRESSURE
WILL REMAIN ACROSS THE REGION...UNDER THE AXIS OF A H5 RIDGE. H85
TEMPS ARE FORECAST TO RANGE FROM 16C ACROSS THE MTNS TO 15C ACROSS
THE PIEDMONT. THE COMBINATION OF MILD LLVL THICKNESSES AND PLENTIFUL
INSOLATION SHOULD SUPPORT HIGH TEMPERATURES NEAR 80 WITHIN THE MTN
VALLEYS TO MID 80S ACROSS THE PIEDMONT. FORECAST SOUNDINGS INDICATE
THAT A SIGNIFICANT H65 INVERSION WILL LINGER THROUGH THURSDAY. A
LAYER LLVL CIN SHOULD REMAIN THROUGH THE DAY...CAPPING SFC BASED
PARCELS.

ON FRIDAY...A DEEP MID LEVEL CLOSED LOW WILL TRACK SW ACROSS THE
NORTHERN PLAINS AND WESTERN GREAT LAKE REGION. SOUTH OF THE
LOW...THE AXIS OF THE MID LEVEL TROUGH WILL DIG EAST ACROSS THE
SOUTHEAST REGION. AT THE SFC...A STRONG COLD FRONT WILL PUSH FROM
MIDDLE TN 12Z FRIDAY TO THE CAROLINA COAST BY 12Z SATURDAY. MID AND
UPPER LEVEL FORCING WILL INCREASE AS A SHORT WAVE AND BAND OF JET
DIVERGENCE CROSSES THE SOUTHERN APPALACHIANS AFTER 12Z SATURDAY. THE
LOW LEVEL ENVIRONMENT WILL FEATURE CAPES BETWEEN 1000-1500 J/KG WITH
HELICITY VALUES BETWEEN 50-100 M2/S2. THIS ENVIRONMENT SHOULD
SUPPORT THE DAYTIME PASSAGE OF A PRE FRONTAL BAND OF CONVECTION
ACROSS THE HIGH TERRAIN. I WILL INCREASE POPS TO CATE TO HIGH LIKELY
ACROSS THE CWA...ESPECIALLY FRIDAY AFTERNOON. GIVEN THE
ENVIRONMENT...IT IS POSSIBLE THAT WELL ORGANIZED QLCS COULD DEVELOP
FRIDAY AFTERNOON OR EVENING. HOWEVER...THE POSSIBILITY OF SVR WEATHER
APPEARS TOO LIMITED TO HIGHLIGHT IN THIS MORNINGS HWO. TEMPERATURES
WILL BE LIMITED BY THICK CLOUDS AND RAINFALL...HIGHS SHOULD REMAIN
AROUND 5 DEGREES BELOW NORMAL.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 330 AM WEDNESDAY...ON SATURDAY...STRONG H85 CAA WILL OCCUR
ACROSS THE REGION...FALLING FROM 10C OVER AVL AT 6Z TO 3C BY 12Z.
LOW TEMPERATURES ARE FORECAST TO RANGE FROM THE MID 40S ACROSS THE
HIGH TERRAIN TO THE MID 50S ACROSS THE PIEDMONT. HIGH TEMPERATURES
WILL LIKELY RANGE 5 TO 8 DEGREES BELOW NORMAL. SUNDAY SHOULD SEE THE
COOLEST TEMPERATURES OF THE PERIOD. THE CENTER SFC HIGH PRESSURE IS
FORECAST TO REACH THE AL/GA LINE BY 12Z SUNDAY. CONDITIONS ACROSS
THE REGION WILL FEATURE DRY...CALM...AND LIMITED SKY COVER. IN
ADDITION...CAA MAY PUSH H85 TEMPS ACROSS THE NRN MTNS FROM 0C TO
-1.5C. SUNDAY MORNING...MINS IN THE MID 30S SHOULD BE COMMON ACROSS
MTN RIDGES. ELSEWHERE....VALUES ARE FORECAST TO RANGE IN THE MID TO
U40S.

EARLY NEXT WEEK...THE CENTER OF HIGH PRESSURE WILL PUSH OFF THE
CAROLINA COAST AS ANOTHER COLD FRONT APPROACHES FROM THE WEST. THIS
PATTERN SHOULD ADVECT WARMER TEMPERATURES AND MOISTURE ACROSS THE
SOUTHERN APPALACHIAN REGION. TEMPERATURES WILL MODIFY THROUGH THE
LATE EXTENDED PERIOD...RETURN TO NEAR NORMAL BY TUESDAY. IN
ADDITION...I WILL MENTION DEVELOPING WIDELY SCATTERED SHOWERS ACROSS
THE CWA ON TUESDAY.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AT KCLT...GENERALLY VFR WITH LIGHT WINDS. WITH A MOSTLY CLEAR/CALM
NIGHT IN STORE...MOST GUIDANCE SUGGESTS THAT MVFR TYPE FOG IS LIKELY
CIRCA SUNRISE ON THU.

ELSEWHERE...ALSO GENERALLY VFR. AREAS OF EARLY MORNING MVFR/IFR
RESTRICTIONS DUE TO FOG ARE LIKELY ON THU...ESPECIALLY IN THE
WESTERN NC MOUNTAINS. KAVL MAY GO BRIEFLY IFR CIRCA SUNRISE.

OUTLOOK...A COLD FRONT WILL MOVE ACROSS THE AREA ON FRIDAY WHICH
WILL TRIGGER SHOWERS AND THUNDERSTORMS...WITH ASSOCIATED
RESTRICTIONS POSSIBLE. BEHIND THE FRONT FRIDAY NIGHT...CLEARING WILL
OCCUR WITH AN EXTENDED PERIOD OF VFR WEATHER ANTICIPATED THROUGH THE
FIRST OF NEXT WEEK.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-17Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  91%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  87%
KAVL       HIGH 100%     HIGH 100%     HIGH  93%     HIGH  86%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  87%
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...NONE.
SC...NONE.

&&

$$
SYNOPSIS...NED
NEAR TERM...LG
SHORT TERM...NED
LONG TERM...NED
AVIATION...LG






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