Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 220705
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
305 AM EDT TUE APR 22 2014

.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION FROM THE WEST TODAY. DRY HIGH
PRESSURE WILL THEN RETURN WEDNESDAY THROUGH THURSDAY. A WEAK COLD
FRONT WILL MOVE THROUGH THE AREA ON FRIDAY...WITH A REINFORCING
FRONT STALLING TO THE NORTH OF THE AREA OVER THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 245 AM...A FULL LATITUDINAL TROF WITH SEVERAL EMBEDDED VORT
MAXES WILL CROSS THE CWFA TODAY. ONE OF THE LEADING VORT MAXES IS
ALREADY CROSSING THE AREA EARLY THIS MORNING...WITH INCREASING
MID-HIGH CLOUDINESS. AT THE SFC...A COLD FRONT IS CURRENTLY ENTERING
THE OH VLY...AND WILL CROSS THE AREA THIS EVENING. DISORGANIZED
PRE-FRONTAL SHOWERS ACRS THE OH/TN VLYS SHUD START TO ENTER THE NC
MTNS RIGHT AROUND DAYBREAK THIS MORNING.

FOR TODAY...GUIDANCE SEEMS TO BE BACKING OFF POPS A TAD...WHICH
ISN/T TOO SURPRISING...AS LLVL FLOW VEERS TO WLY BEFORE THE FRONT
ARRIVES. THERE IS SOME Q-VECTOR CONVERGENCE AND UPR JET DIVERGENCE
AROUND 18Z ACRS WRN NC. BUT EVEN THAT IS NOT THAT IMPRESSIVE IN ANY
OF THE PROGS. BLENDING IN THE 00Z NAM/GFS...I ACTUALLY GET A
DECREASE IN POPS EAST OF THE MTNS...IN THE HIGH-END CHC TO LOW-END
LIKELY RANGE. TEMPS SHUD BE ABLE TO WARM INTO THE MID-UPR 70S.
HOWEVER...WITH LEADING SHORTWAVE ENERGY WORKING IN THIS
MORNING...MID LVL CLOUDINESS MAY HAMPER DIURNAL HEATING SOMEWHAT. AS
FOR SEVERE POTENTIAL...IT STILL DOES NOT LOOK GOOD. FCST SNDGS SHOW
MOIST MID LVLS WITH WEAK LAPSE RATES AND GENERALLY LESS THAN 25 KTS
OF 0-6KM BULK SHEAR. HIGH RES MODELS SHOW SORT OF SHOTGUN CONVECTIVE
COVERAGE WITH A FEW STRONGER CELLS...PRIMARILY ACRS THE NC PIEDMONT.
SO I THINK WE WILL SEE MAINLY SCATTERED TO NUMEROUS SHWRS WITH
SCATTERED TSTMS...A FEW OF WHICH MAY APPROACH SEVERE LIMITS IF WE
CAN MANAGE TO DESTABILIZE TO 1500-2000 J/KG OF SBCAPE (AS THE GFS
SHOWS). BUT THE GFS SEEMS TOO HIGH WITH SFC DWPTS ACRS MUCH OF THE
WARM SECTOR...SO MAY BE AN OUTLIER. THE NEW DAY ONE CONVECTIVE
OUTLOOK STILL HAS ONLY GENERAL THUNDER TODAY ACRS THE REGION. WILL
MENTION THUNDER THREAT IN THE HWO...BUT IF ANY MENTION OF
SEVERE...JUST THAT IT CANNOT BE RULED OUT.

TONIGHT...GUIDANCE IN GOOD AGREEMENT ON DRY AIR AND CAA WORKING INTO
THE AREA QUICKLY THIS EVENING. SO POPS PRETTY MUCH END BY 00Z THIS
EVENING...SAVE FOR A FEW SHWRS LINGERING ALONG THE TN/NC BORDER WITH
HELP FROM NW UPSLOPE FLOW. FLOW STRENGTHENS TO 40-50 KTS AT 850 MB
IN THE NC MTNS WITH A STRONG BUT LOW INVERSION...HELPING PRODUCE
STRONG CHANNELED VALLEY WINDS. RIGHT NOW...IT LOOKS LIKE WINDS SHUD
GENERALLY STAY SUB-ADVISORY LEVELS. TEMPS SHUD BE ABLE TO FALL INTO
THE UPR 30S TO LWR 40S IN THE MTNS AND MID-UPR 40S ACRS THE PIEDMONT
BEHIND THE FRONT.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 225 AM TUESDAY...DRY HIGH PRESSURE WILL BEGIN TO BUILD DOWN
OVER THE FORECAST AREA ON WEDNESDAY...WITH RESIDUAL BRISK NW FLOW
LINGERING THROUGH AT LEAST THE MORNING HOURS. THERE IS SOME
POTENTIAL FOR AN OROGRAPHICALLY INDUCED CIRRUS SHIELD TO FORM IN THE
MTN WAVE FLOW OVER WRN NC WED MORNING...BUT UPSTREAM MOISTURE
REMAINS A QUESTION MARK. OTHERWISE...EXPECT DRY CONDITIONS WED WITH
MAX TEMPS NEAR CLIMO IN THE SRN TIER AND ONE TO TWO CATEGORIES BELOW
NORMAL IN THE NRN TIER.

FLAT UPPER RIDGING WILL THEN BUILD IN FROM THE WEST LATE WED AND
LINGER THROUGH THU. SPOTTY 30S FOR OVERNIGHT LOWS WILL BE POSSIBLE
IN THE NC MTNS THU MORNING WITH GOOD RADIATION...BUT WITH TEMPS
PROBABLY A LITTLE TOO WARM FOR FROST. RETURN FLOW MOISTURE WILL
START TO SET UP FROM THE SW THU AFTN AND EVENING. THIS MIGHT
CONTRIBUTE A FEW MORE CLOUDS...BUT POPS STILL LOOK UNLIKELY. TEMPS
WILL HOVER NEAR CLIMATE NORMS.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 230 AM EDT TUESDAY...A DEAMPLIFYING SHORTWAVE WILL CROSS THE
REGION EARLY FRI. THE ASSOCIATED SFC FRONT/TROUGH SHOULD ALSO CROSS
THE REGION BY EARLY AFTN...WITH THIS TIMING LIMITING INSTABILITY
SOMEWHAT. HOWEVER...ANY SLOWING OF THE FORWARD PROGRESS OF THE WEAK
FROPA COULD ALLOW CONVECTION TO CONTINUE THROUGH MID AFTN...WHEN SFC
BASED CAPE VALUES SHOULD BE 1000 TO 1500 J/KG ALONG THE SE PIEDMONT.
WILL FEATURE CHANCE POPS THROUGHOUT FOR SHOWERS AND THUNDERSTORMS
BUT SEVERE WEATHER PROBABILITIES REMAIN LOW.

A BROAD UPPER RIDGE SHOULD BE IN PLACE OVER THE SE THROUGH THE
WEEKEND. UNDER THE RIDGE...A BACKDOOR SFC COLD FRONT WILL STALL
NORTH OF THE FORECAST AREA SAT INTO SAT NIGHT. THIS WILL KEEP THE
REGION IN THE WARM SECTOR SUN THROUGH MON AS LOW PRES RIDES EAST
ALONG THE STALLED BOUNDARY TOWARD THE APPALACHIANS. DIURNAL SHOWER
CHANCES WILL STEADILY INCREASE SUNDAY THROUGH MONDAY AS MOISTURE AND
INSTABILITY BUILD IN THE SW FLOW.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
KCLT AND ELSEWHERE...LITTLE CHANGE IN THINKING FROM PREVIOUS TAFS.
INCREASING MID-HIGH CLOUDS THRU THE MORNING HOURS AHEAD OF AN
APPROACHING COLD FRONT. THE FRONT WILL CROSS THE AREA THIS
AFTN...WITH SCATTERED TO NUMEROUS SHWRS AND A FEW TSTMS. WILL
CONTINUE WITH PROB30 AND A PERIOD OF VCTS OR PREVAILING TSRA WHEN
EXPECT BEST CHC OF IMPACTS...MAINLY EARLY TO MID AFTN. ANY VSBY/CIG
RESTRICTIONS SHUD BE BRIEF WHERE PRECIP DIRECTLY AFFECTS THE
TERMINALS. DRY AIR AND CAA SHUD CUT OFF SHRA ACTIVITY AND SCOUR OUT
LOW VFR CLOUDS QUICKLY THIS EVENING...WITH NW WINDS LINGERING THRU
THE NIGHT. EXPECT STRONGEST WINDS AT KAVL WITH GUSTS IN THE 20-25 KT
RANGE OVERNIGHT.

OUTLOOK...DRY HIGH PRES RETURNS FOR WEDNESDAY/THURSDAY. ANOTHER COLD
FRONT WITH POTENTIAL FOR SHOWERS/TSTMS IS THEN EXPECTED TO CROSS THE
REGION FRIDAY.

CONFIDENCE TABLE...

            07-13Z        13-19Z        19-01Z        01-07Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH  98%     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 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...HG
NEAR TERM...ARK
SHORT TERM...HG
LONG TERM...HG
AVIATION...ARK






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