Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 221652
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1152 AM EST SAT NOV 22 2014

.SYNOPSIS...
DRY HIGH PRESSURE OVER THE REGION WILL GIVE WAY TO A VERY MOIST
SOUTHERLY FLOW ON SUNDAY. DRIER AND LESS MILD AIR WILL THEN
OVERSPREAD THE AREA IN THE WAKE OF A COLD FRONT BY TUESDAY. AN AREA
OF LOW PRESSURE IS THEN EXPECTED TO DEVELOP AND MOVE UP THE
SOUTHEAST COAST WEDNESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
1150 AM EST SATURDAY UPDATE...HAVE DECREASED THE MAX TEMPS TODAY BY
A FEW DEGREES PER LATEST SURFACE OBS TREND. OTHERWISE...THE CURRENT
FORECAST LOOKS TO BE IN GOOD SHAPE.

630 AM UPDATE...NO SIGNIFICANT CHANGES AT THIS HOUR WITH THE
WEATHER QUIESCENT AND THE FCST LOOKING TO BE ON TRACK.

AS OF 315 AM...SFC HIGH PRESSURE WILL MOVE OFF THE MID-ATLANTIC
COAST TODAY WHILE THE SERN CONUS REMAINS UNDER A FLAT UPPER RIDGE.
SELY WINDS WILL PREVAIL ACRS THE AREA WHICH WILL PROMOTE GRADUAL
WARM ADVECTION AND REBOUNDING DEWPOINTS BY THE AFTN...THESE
PRECEDING A WARM FRONT LIFTING UP FROM THE GULF COAST WITH THE
DEVELOPING SRN STREAM SYSTEM THAT WILL AFFECT NRN GA AND THE
CAROLINAS BEGINNING SUNDAY. MAX TEMPS THIS AFTN WILL REMAIN A
CATEGORY OR TWO BELOW CLIMO.

ISENTROPIC UPGLIDE IS INITIALLY NOT VERY STRONG BUT SHOULD BE CAPABLE
OF INTRODUCING SOME STRATUS OR STRATOCU OVER THE SAVANNAH VALLEY AND
ADJACENT AREAS LATE IN THE DAY. THE UPGLIDE STRENGTHENS OVERNIGHT
TONIGHT...DOING SO MORE QUICKLY AFTER MIDNIGHT...WHEN STRATUS SHOULD
SPREAD OVER THE ENTIRE AREA. GFS/EC ARE IN FAIR AGREEMENT WRT
QPF...BOTH BEING MORE BULLISH THAN THE NAM/CMC BUT NOT YET
SIGNIFICANT. WITH THE LLVL FLOW BACKING SLIGHTLY AND SUGGESTING
UPSLOPE ENHANCEMENT IN ADDITION TO THE INCREASINGLY MOIST/DEEP
ISENTROPIC LIFT...BY DAYBREAK SUNDAY HIGH LIKELY TO CATEGORICAL POPS
ARE APPROPRIATE OVER THE SRN FACING ESCARPMENT AND AREAS TO ITS
SOUTH. IN-SITU CAD WEDGING SHOULD BE UNDERWAY BY THIS TIME...THE
INCUMBENT HIGH PRESSURE HAVING SHIFTED OFFSHORE WITH RAINFALL
CONTINUING TO SPREAD NWD THRU SUNDAY MORNING. WILL EXPECT TEMPS TO
FALL SLOWLY UNDER THE CLOUD COVER BUT WET-BULB DOWN FAIRLY QUICKLY
WHERE PRECIP IS FALLING IN THE EARLY MRNG HRS...WITH MINS ENDING UP
NEAR RAW MODEL VALUES.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...A COMPACT/INTENSE SHORT WAVE TROUGH WILL
DAMPEN AS IS LIFTS OUT OF THE LOWER MISS VALLEY AND INTO THE
CONFLUENT UPPER FLOW REGIME ACROSS THE MID-ATLANTIC ON SUNDAY.
ALTHOUGH THERE ARE SOME MODEL DISAGREEMENTS IN THE DETAILS REGARDING
THIS FEATURE...DIFFERENCES IN IMPLIED SENSIBLE WEATHER ARE NOT
SIGNIFICANT. SIGNIFICANT ISENTROPIC UPGLIDE WILL DEVELOP ACROSS THE
AREA BY EARLY SUNDAY...AND CAT TO LIKELY POPS ARE EXPECTED AT THE
START OF THE PERIOD ACROSS THE SOUTHWEST QUADRANT OF THE FORECAST
AREA...WITH CATEGORICAL POPS SPREADING NORTHEAST ACROSS THE
REMAINDER OF THE FORECAST AREA THROUGHOUT SUNDAY. A DRY SLOT WILL
BEGIN OVERSPREADING THE AREA BY SUNDAY EVENING...BRINGING AN END TO
HIGH PRECIP PROBABILITIES. THE TEMP FORECAST WILL BE PROBLEMATIC ON
SUNDAY...AS PRECIP FALLING INTO A RELATIVELY DRY AIR MASS SHOULD
PROMPT DEVELOPMENT OF IN SITU CAD. HOWEVER...SOME AREAS ACROSS THE NC
PIEDMONT WILL LIKELY WARM UP A BIT BEFORE THE PRECIP ARRIVES.
FORECAST MAXES WILL RANGE FROM 10-15 DEGREES BELOW NORMAL ACROSS THE
BLUE RIDGE/FOOTHILLS AREAS...TO 5-10 DEGREES BELOW NORMAL ACROSS THE
NC PIEDMONT.

A MENTION OF THUNDER WILL CONTINUE TO BE CARRIED ACROSS THE
SOUTHEAST ZONES SUNDAY AFTERNOON...AS AT LEAST ELEVATED BUOYANCY IS
POSSIBLE. HOWEVER...MUCH OF THE CWA SHOULD BE QUITE STABLE WITHIN IN
SITU CAD REGIME. TOTAL QPF IS EXPECTED TO EXCEED 2 INCHES ACROSS THE
SOUTHERN ESCARPMENT...WITH 1-1.5 INCHES EXPECTED IN MOST OTHER
LOCATIONS...WITH PERHAPS A SECOND MAXIMA EXCEEDING 1.5 INCHES ALONG
CAD BOUNDARY/COASTAL FRONT.

CAD WILL BEGIN THE EROSION PROCESS SUNDAY NIGHT AS WIDESPREAD PRECIP
ENDS AND STRONG/DEEP SW FLOW DEVELOPS DOWNSTREAM OF THE MAIN REGION
OF CENTRAL CONUS HEIGHT FALLS. MONDAY SHOULD ACTUALLY BE QUITE
WARM...WITH TEMPS RETURNING TO WELL-ABOVE NORMAL LEVELS UNDERNEATH
ANOMALOUSLY HIGH HEIGHTS. IN FACT...THE NAM DEVELOPS AN APPRECIABLE
DEGREE OF CAPE BY MONDAY AFTERNOON...IN ADVANCE OF APPROACHING COLD
FRONT. THAT BEING SAID...FORECAST SOUNDINGS DEPICT AN INHIBITED AIR
MASS DUE TO WARM MID-LEVEL TEMPS. MEANWHILE...NONE OF THE OTHER
OPERATIONAL MODELS ARE ANYWHERE NEAR AS UNSTABLE. THEREFORE...WILL
HOLD ON TO TOKEN SMALL CHANCES TO ACCOMPANY FROPA IN THE OTHERWISE
WEAKLY FORCED ENVIRONS...WITH A CHANCE FOR THUNDER MAINLY MENTIONED
ACROSS THE SOUTHERN ZONES.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 345 AM SATURDAY...THE GLOBAL MODELS ESTABLISH SOUTHEAST
COASTAL CYCLOGENESIS BY EARLY WEDNESDAY...WITH SOME LIGHT PRECIP
DEVELOPING ACROSS THE FORECAST AREA AS A RESULT...PRIMARILY EASTERN
AREAS. POPS HAVE BEEN INCREASED A BIT FROM LATE TUE NIGHT INTO
WED...WITH LOW CHANCES FOR LIGHT RAIN MANLY CONFINED TO THE I-77
CORRIDOR. THERE COULD BE A PERIOD OF LIGHT NW FLOW SNOW AS THE UPPER
TROUGH AXIS PASSES OVER THE AREA WED NIGHT/THANKSGIVING...
PARTICULARLY IF THE MORE AMPLIFIED ECMWF SOLUTION VERIFIES CLOSE TO
REALITY. OTHERWISE...NEXT WEEK WILL SEE A RETURN TO PRIMARILY DRY
AND UNSEASONABLY COOL CONDITIONS AS THE EASTERN LONG WAVE TROUGH
RESUMES ITS POSITION.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AT KCLT AND ELSEWHERE...DRY HIGH PRESSURE EAST OF THE REGION WILL
MAINTAIN VFR CONDITIONS AND LIGHT WINDS THROUGH THE DAY. THE WINDS
WILL INITIALLY PREVAIL NELY...THEN VEERING TO SE AROUND MIDDAY.
SOUTHERLY RETURN FLOW WILL AMPLIFY TONIGHT IN THE LOW LEVELS LEADING
TO INCREASINGLY STRONG WARM/MOIST UPGLIDE...AND SUBSEQUENTLY
INCREASING POPS AND LOWERING CIGS TO MVFR. THIS WILL GENERALLY
HAPPEN FROM SW TO NE ACRS THE SITES...BUT AREAS ALONG THE BLUE RIDGE
MAY WORSEN A LITTLE FASTER. DEVELOPMENT OF COLD AIR DAMMING TONIGHT
IS LIKELY TO BACK WINDS TO NE AGAIN AFTER MIDNIGHT.

OUTLOOK...RESTRICTIVE CIGS AND PRECIPITATION WILL BE WIDESPREAD
SUNDAY AS A WARM FRONT LIFTS THRU THE REGION FROM THE SOUTH. BRIEF
DRYING FOLLOWS THE FRONT MON-TUE...WITH PRECIP POSSIBLY RETURNING
WED.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  90%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  80%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  90%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     MED   70%
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...JDL
NEAR TERM...JOH/WIMBERLEY
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...WIMBERLEY



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