Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 021804
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
204 PM EDT THU JUL 2 2015

.SYNOPSIS...
A BROAD UPPER LEVEL TROUGH WILL REMAIN OVER THE SOUTHEAST THROUGH
THE WEEKEND...STEERING A SERIES OF WEAK LOW PRESSURE SYSTEMS OVER
THE REGION. THESE SYSTEMS WILL INCREASE RAIN AND THUNDERSTORM
CHANCES EACH AFTERNOON AND EVENING. HIGH TEMPERATURES WILL BE NEAR
NORMAL THROUGH NEXT WEEK...WITH LOWS JUST ABOVE NORMAL.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 145 PM EDT...AN OUTFLOW FROM EARLIER CONVECTION WORKING
SOUTHWARD OVER THE WESTERN THIRD OF THE CWFA IS FINALLY ENCOUNTERING
MORE INSTABILITY...WITH 1500 TO 2000 J/KG OF SBCAPE OVER THE WESTERN
UPSTATE AND NE GA THIS AFTN. POPS HAVE BEEN RATCHETED UP OVER THE
THIS AREA FOR A FEW HOURS THIS AFTERNOON...AND HAVE BACKED AWAY FROM
THE HIGHER POPS PREVIOUSLY INDICATED BY THE MESOCALE MODELS FOR
CONVECTION COMING OFF THE BLUE RIDGE INTO THE NC FOOTHILLS AND
PIEDMONT. THIS IS POSSIBLY JUST THE FIRST WAVE OF MANY...AS
ADDITIONAL SHORTWAVES EMBEDDED IN THE H5 TROUGH WILL CROSS THE
FORECAST AREA LATER THIS AFTERNOON AND EARLY THIS EVENING.

YET MORE VORTICITY LOBES WILL CROSS THE BASE OF THE SOUTHERN
APPALACHIANS LATER TONIGHT THROUGH FRIDAY AS THE TROUGH DEEPENS TO
THE WEST FROM THE LOWER OH VALLEY TO THE MS RIVER VALLEY. WESTERLY
850 MB FLOW WILL INCREASE TONIGHT THROUGH FRI ACROSS THE SRN TIER AS
THE 850 MB LOW CENTER DEEPENS SLIGHTLY OVER THE OH VALLEY. THE
FORECAST AREA WILL STAY SOLIDLY WARM SECTOR THROUGH THE NEAR TERM
PERIOD AS A SURFACE WAVE MOVES ALONG THE STALLED BOUNDARY FROM THE
LOWER OH VALLEY THROUGH THE CENTRAL APPALACHIANS. ANTICIPATE A
SMALLER THAN USUAL DIURNAL RANGE ON TEMPS WITH PLENTY OF
CLOUDS/DEBRIS...AND WILL NEED TO SHOTGUN HIGH CHANCE TO LOW END
LIKELY POPS FOR MUCH OF THE AREA BEYOND THE IMMEDIATE NEAR TERM
GIVEN THE MULTIPLE SHORTWAVES AND MOIST PROFILES. EXPECT GUSTY WINDS
WITH MIXING AGAIN ON FRI AFTN. HEAVY RAIN WILL POSE A LOCALIZED
HYDRO THREAT JUST ABOUT ANYWHERE THAT TRAINING OCCURS...WITH THE SW
MTNS STANDING THE BEST CHANCE OF FLOODING. CONFIDENCE REMAINS TOO
LOW FOR A FLASH FLOOD WATCH SINCE COVERAGE WILL BE HIGHEST IN THE
WESTERN MTNS BUT RATES WILL BE BETTER IN MORE UNSTABLE AREAS.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
OF 240 AM THURSDAY...THE SHORT TERM FCST PICKS UP AT 12Z ON
FRIDAY WITH THE UPPER TROF FLATTENING OUT WHILE NUMEROUS LOBES OF
SHORTWAVE ENERGY STREAM ACROSS THE FCST AREA FROM THE WEST.

ON FRIDAY...DEEP LYR MOISTURE WILL BE IN PLACE OVER THE REGION FRI
MORNING AS A COMPLEX SFC LOW DEVELOPS JUST TO THE NORTH. AS THE LOW
SLOWLY MOVES TOWARDS THE COAST...ANOTHER LEE TROF WILL SET UP OVER
THE CAROLINAS LATE FRI AND LINGER WELL INTO SAT. POPS STEADILY RAMP
UP THRU THE DAY/EVENING WITH HIGH END CHANCE TO LIKELY VALUES
CARRIED OVER THE ENTIRE CWFA BY THE AFTERNOON. QPF AMOUNTS HAVE BEEN
LOWERED A BIT SINCE YESTERDAYS FCST...HOWEVER A SOLID INCH OR SO IS
POSSIBLE OVER SOME OF THE UPSLOPE AREAS AND HIGHER TERRAIN. SPC
KEEPS OUR CWFA IN THE MARGINAL RISK AREA WITH THE BIGGEST THREAT
BEING SVR STRAIGHT LINE WINDS. AS WE MOVE INTO SAT...THE SFC
LOW BEGINS TO MOVE OFF THE COAST AND ANOTHER LEE TROF DEVELOPS IN
ITS WAKE KEEPING WINDS OUT OF THE SW AND TIGHTENING THE PRESSURE
GRADIENT. PW VALUES WILL REMAIN HIGH THRU SAT...SO FLASH FLOODING
CONTINUES TO BE A CONCERN GOING FORWARD. TEMPS START OUT ABOUT 2 TO
4 DEGREES BELOW CLIMO ON FRI AND WARM A FEW DEGREES OVER THE NEXT
FEW DAYS ENDING RIGHT AROUND NORMAL FOR EARLY JULY.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
OF 240 AM THURSDAY...THE MEDIUM RANGE FCST PICKS UP AT 12Z ON
SUNDAY WITH HEIGHTS RISING AS BROAD UPPER RIDGING DEVELOPS OVER MUCH
OF THE SOUTHERN CONUS. THE MODELS GENERATE NUMEROUS WEAK UPPER
SHORTWAVES THRU THE PERIOD WITH WEAK UPPER WINDS PREVAILING THRU DAY
7. NO SIGNIFICANT PATTERN CHANGES ARE EXPECTED THRU THE MEDIUM RANGE
WITH RIDGING REMAINING IN PLACE WELL BEYOND DAY 7. AT THE SFC...THE
REGION WILL REMAIN UNSETTLED THRU MOST OF THE PERIOD WITH PREVAILING
SOUTH TO SWLY LOW LVL FLOW. THE CWFA IS EXPECTED TO REMAIN UNDER
WEAK LEE TROFFING ON SUN AND MON AS A SERIES OF SHORT LIVED MESO
LOWS ATTEMPT TO SPIN UP OVER THE CAROLINAS. THE LONG RANGE GUIDANCE
SUGGESTS THAT A MORE SUBSTANTIAL FRONT WILL APPROACH THE FCST AREA
FROM THE WEST ON WED AND THURS...HOWEVER THE STRENGTH AND TIMING OF
THE SYSTEM IS UNCLEAR. THE MODELS AGREE THAT DEEPER LYR MOISTURE WILL
PERSIST OVER THE REGION THRU MOST OF THE PERIOD WITH THE HIGHEST PW
VALUES GENERALLY OVER THE NORTHERN ZONES EARLY IN THE PERIOD AND
THEN SHIFTING SOUTHWARD ON MON AND TUES. AS FOR THE SENSIBLE
FCST...I KEPT DIURNAL HIGH END CHANCES FOR CONVECTION EACH
DAY/EVENING WITH SOME LIKELY POPS OVER THE NC/TENN BORDER REGION FOR
SUN. TEMPS START OUT AROUND CLIMATOLOGY ON SUN AND WARM SLIGHTLY
OVER THE NEXT FEW DAYS WITH HIGHS TOPPING OUT JUST ABOVE CLIMO BY
EARLY NEXT WEEK.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AT KCLT...CONVECTION DEVELOPING ON THE EARLY DAY MCS OUTFLOW IS
EXTENDING EAST TOWARD THE KCLT VICINITY THIS AFTN. THE CURRENT TEMPO
TSRA FROM 19Z STILL LOOKS WELL TIMED WITH ASSOCIATED MVFR
RESTRICTIONS UNDER ANY HEAVY THUNDER SHOWERS. ANTICIPATE LOW END
GUSTS IN BOTH THE GRADIENT FLOW WITH MIXING AND IN ANY TSTMS WITH
LIMITED DCAPE. THE NAM REMAINS MOST BULLISH ON OVERNIGHT MVFR CLOUDS
DEVELOPING...BUT THE MOS REMAINS UNEXCITED. WILL HOLD OFF FOR NOW
GIVEN THE LIKELIHOOD OF CONSIDERABLE MID/HIGH DEBRIS CLOUDS. GIVEN
THE MULTIPLE PASSING SHORTWAVES...SHOWERS OR ISOLD TSTMS WILL
CONTINUE TO POSSIBLE AT JUST ABOUT ANY TIME OVERNIGHT THROUGH FRIDAY
MORNING...BUT WITH A BETTER CHANCE FROM MID MORNING ON FRIDAY.

ELSEWHERE...TEMPO TSRA WITH 20 TO 30 KT GUSTS LOOKS HIGHLY LIKELY AT
THE UPSTATE SITES ALONG THE OUTFLOW LINE THIS AFTN...WITH PRECIP
GENERALLY MORE SHOWERS FROM KAVL TO KHKY. ANTICIPATE CONTINUED
ROUNDS OF SHOWERS WITH PASSING UPPER SHORTWAVES TONIGHT THROUGH
FRIDAY MORNING...WITH SCATTERED TSTMS POSSIBLE AT ANY TIME AS WELL.
WE COULD SEE A REPEAT OF SPOTTY LOW STRATUS AGAIN FRI MORNING GIVEN
ALL THE MOISTURE AROUND...BUT THERE WILL ALSO BE PLENTY OF MID/HIGH
DEBRIS CLOUDS. WILL CONFINE THE OVERNIGHT RESTRICTIONS TO KAVL AND
KHKY FOR NOW. EXPECT UPSTATE TAF SITES TO START GUSTING AGAIN LATE
IN THE PERIOD AS MIXING GRADUALLY IMPROVES AND 850 MB WESTERLY WINDS
INCREASE.

OUTLOOK...A GRADUALLY WEAKENING UPPER TROUGH WILL SUPPORT MAINLY
AFTERNOON AND EVENING THUNDERSTORMS THROUGH EARLY NEXT WEEK.
RESTRICTIONS MAY OCCUR WITH PASSING STORMS...AND EACH MORNING OVER
RAIN SOAKED AREAS.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  87%
KGSP       HIGH 100%     HIGH 100%     HIGH  94%     HIGH  92%
KAVL       HIGH 100%     HIGH 100%     HIGH  88%     HIGH  83%
KHKY       HIGH 100%     HIGH 100%     HIGH  94%     HIGH  83%
KGMU       HIGH  92%     HIGH 100%     HIGH  92%     HIGH  92%
KAND       HIGH 100%     HIGH 100%     HIGH  95%     HIGH  98%

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...JAT
NEAR TERM...HG
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...HG


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