Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 031800
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
200 PM EDT FRI JUL 3 2015

.SYNOPSIS...
A BROAD UPPER LEVEL TROUGH WILL REMAIN OVER THE SOUTHEAST THROUGH
MONDAY...STEERING A SERIES OF WEAK DISTURBANCES OVER THE REGION.
THESE FEATURES WILL INCREASE RAIN AND THUNDERSTORM CHANCES EACH
AFTERNOON AND EVENING...AND KEEP SKIES CLOUDIER THAN USUAL. SLIGHT
DRYING WILL OCCUR TUESDAY...BEFORE ANOTHER FRONT PUSHES THROUGH IN
THE MIDDLE OF THE WEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 145 PM EDT...WATER VAPOR IMAGERY SHOWS A MID/UPPER LEVEL
TROUGH DIGGING SE INTO LOWER OH VALLEY THIS AFTERNOON...WITH
NUMEROUS SHORTWAVES RIPPLING EAST IN THE WESTERLY FLOW ACROSS
KY/TN/GA. MEANWHILE...A WAVY SURFACE BOUNDARY PERSISTS ROUGHLY WEST
TO EAST ALONG THE INTERSTATE 40 CORRIDOR...AND THIS BOUNDARY IS
EXPECTED TO REMAIN STALLED ALONG OR NEAR THE NRN BORDER OF OUR
FORECAST AREA THROUGH THE NEAR TERM. THESE FEATURES WILL INTERACT
WITH PRECIPITABLE WATER VALUES OF 1.75 INCHES OR GREATER ACROSS THE
FORECAST AREA TO GENERATE FAIRLY HIGH COVERAGE OF PRECIPITATION AND
LOCALLY HEAVY RAINFALL...ESPECIALLY OVER THE MTNS. A FLASH FLOOD
WATCH MAY BE NEEDED FOR SOME MOUNTAIN COUNTIES.

AT PRESENT...REGIONAL RADARS SHOW PRECIPITATION MOVING EAST IN THE
CYCLONIC FLOW ACROSS ERN KY...ERN TN...AND AL/GA. THROUGH LATE AFTN
AND INTO THE EVENING HOURS...COVERAGE WILL BE BEST ALONG THE NRN
TIER CLOSER TO THE LOW LEVEL CONVERGENCE AXIS NEAR AND NORTH OF
INTERSTATE 40 AS A SFC WAVE MOVES EAST ALONG THE BOUNDARY. THE HRRR
HAS ADDITIONAL CONVECTION DEVELOPING ALONG THE ERN SLOPES OF THE
BLUE RIDGE LATE THIS AFTN AND MAKING A RUN EASTWARD THROUGH THE NC
PIEDMONT. THIS SEEMS REASONABLE SINCE MUCH OF THIS AREA DID NOT GET
WORKED OVER BY MORNING CONVECTION/RAIN AND SOME 1500+ SBCAPE VALUES
ARE APPARENT IN SFC LAPS DATA.

OTHERWISE...A SERIES OF SHORTWAVES WILL LIKELY CROSS THE REGION
TONIGHT THROUGH SAT...BUT WITH THE ASSOCIATED FORCING HARD TO TIME.
WILL PARE BACK POPS W TOWARD THE MTNS FOR MUCH OF THE NIGHTTIME
HOURS...WITH A FOCUS MAINLY ON THE TN BORDER COUNTIES OVERNIGHT
WHERE WESTERLY LOW LEVEL UPSLOPE WILL BE BEST. THERE IS GOOD
CONSENSUS ON INCREASING UPPER JET SUPPORT LATE TONIGHT INTO
SATURDAY...AND COVERAGE MAY BE RESURGENT FROM THE SW TOWARD
DAYBREAK. CLOUD COVER AND EARLY DAY PRECIPITATION COULD ONCE AGAIN
KEEP INSTABILITY LIMITED FOR SATURDAY...BUT THE CONTINUED MOISTURE
EAST OF THE TROUGH WILL REQUIRE CATEGORICAL POPS ACROSS THE WRN MTNS
TO CHC POPS EAST OF INTERSTATE 77 THROUGH THE DAY. EXPECT A SMALLER
THAN CLIMO DIURNAL RANGE ON TEMPS WITH CLOUDS/PRECIP.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 315 AM FRI...AS UPPER TROUGH SWINGS ACRS THE SRN APPALACHIANS
SATURDAY...SFC LOW IS PUSHED OFF THE MID-ATLANTIC COAST. HOWEVER THE
BASE OF THE TROUGH CONCURRENTLY SHEARS OFF LEAVING A SLOW-MOVING
SHORTWAVE TO LINGER OVER OUR REGION INTO EARLY MONDAY. SOME SEMBLANCE
OF THE FRONT WILL REMAIN ACROSS THE CAROLINAS...AND THOUGH IT IS
INITIALLY HARD TO IDENTIFY ANY DISTINCT SOURCE OF FORCING...WEAK
CONVERGENCE SHOULD ENHANCE PRECIP CHANCES IN ADDITION TO EMBEDDED
VORTICES HIGHER ALOFT. ON SUNDAY THE BOUNDARY IS STRENGTHENED AS HIGH
PRESSURE BUILDS EWD IN THE WAKE OF THE LARGER SCALE TROUGH. DEEP
MOISTURE WILL REMAIN IN PLACE BOTH DAYS AND ROUNDS OF HEAVY RAIN WILL
CONTINUE...WITH PWAT VALUES BEING ABOVE THE 90TH PERCENTILE AT TIMES.
WINDS ALOFT WILL RELAX AS THE LOW PULLS AWAY SATURDAY...AND PROFILES
WILL REMAIN UNIDIRECTIONAL THRU THE PERIOD...SO SLOW MOVING AND/OR
TRAINING CELLS WILL BE A CONCERN. POPS AND QPF ARE EXPECTED TO BE
HIGHER SUNDAY ON ACCOUNT OF THE ENHANCED LLVL CONVERGENCE. CLOUD
COVER WILL LIMIT TEMPS TO ABOUT A CATEGORY BELOW CLIMO.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 130 PM FRIDAY...WE WILL HAVE BRIEF UPPER RIDGING MONDAY NIGHT
INTO TUESDAY AHEAD OF THE NEXT UPPER TROUGH WITH ITS ASSOCIATED
SURFACE COLD FRONT. THERE WILL STILL BE ENOUGH LOW LEVEL MOISTURE
MONDAY EVENING AND LATE DAY CONVECTION WILL GRADUALLY DIMINISH
OVERNIGHT. LOW LEVEL CONVERGENCE WILL BE WEAK TUESDAY...ESPECIALLY
FOR THE FOOTHILLS AND PIEDMONT. THE APPROACHING COLD FRONT WILL BE
ORIENTED SW TO NE FROM NORTH TX TO THE EASTERN GREAT LAKES
TUESDAY. THE FRONT WILL BECOME NEARLY STATIONARY WED TO FRI WHILE
ORIENTED WEST TO EAST WITH WAVES OF ENERGY RIDING ALONG THE FRONT
CREATING PERIODS OF ENHANCED CONVECTIVE ACTIVITY. THE VARIOUS MODELS
HAVE DIFFERING SOLUTIONS FOR DAYS 6 AND 7 WITH THE ECMWF PUSHING THE
COLD FRONT FARTHER SOUTH WITH SOME SUPPORTIVE UPPER TROFINESS.  THE
GFS HAS MCS FEATURES PASSING FROM THE MISS VALLEY TO OHIO VALLEY
WITH LITTLE EFFECTS ON THE NC MTNS. OVERALL...THE WEATHER PATTERN
WILL CONTINUE TO BE UNSETTLED FOR OUR REGION WITH MAX TEMPS SLIGHTLY
BELOW NORMAL TUES WITH SLIGHT WARMING TO AT LEAST NORMAL MAXES AND
EVEN A LITTLE ABOVE NORMS.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...THERE WAS LITTLE MORE THAN ISOLD SHOWERS NEAR THE AIRFIELD
AT ISSUANCE TIME...BUT MESOSCALE MODELS INDICATE CONVECTION
DEVELOPING EAST OFF THE MTNS THIS AFTN AND MAKING A RUN OUT ACROSS
THE NC PIEDMONT THROUGH LATE AFTN. WILL THUS FEATURE TEMPO TSRA
STARTING AT 19Z. NONE OF THE PROFILES OR MOS INDICATE LOW CLOUDS
DEVELOPING OVERNIGHT...BUT THE GUIDANCE WAS POOR FOR LOW CLOUDS THIS
MORNING. WILL HINT AT STRATUS DEVELOPMENT WITH FEW020 IN THE TAF FOR
THE OVERNIGHT HOURS. EXPECT SW WINDS TO GUST OCCASIONALLY...BUT
LIMITED HEATING IS CAPPING MIXING AND GUST POTENTIAL. SW FLOW WILL
PICK UP AGAIN MID MORNING ON SAT.

ELSEWHERE...KAVL AND THE FOOTHILLS TAFS HAVE BEEN LARGELY FREE OF
CONVECTION SINCE THE MORNING SYSTEM. HOWEVER...PROFILES ARE
REBOUNDING AND SBCAPE VALUES ARE BUILDING SLIGHTLY TO PERMIT SHOWER
REDEVELOPMENT. THE BEST CHANCE OF LATE AFTN THUNDER WILL BE FROM
KAVL TO KHKY NEARER THE LOW LEVEL CONVERGENCE AXIS. ANTICIPATE
MOSTLY LOWER END VFR CIGS...EXCEPT WITH RESTRICTIONS IN ANY
SHRA/TSRA...AND THEN LOWER STRATUS DEVELOPING AGAIN TONIGHT. THE
GUIDANCE CONSENSUS IS MVFR...BUT IFR WILL ONCE AGAIN BE POSSIBLE.
EXPECT LOW END GUSTS AT THE UPSTATE SITES IN THE SW FLOW WITH MIXING
THIS AFTN...OTHERWISE...STEADY WSW TO SW FLOW THROUGHOUT...EXCEPT
MOSTLY NW AT KAVL. CONVECTION MAY RETURN QUICKLY FROM THE SW EARLY
SAT WITH THE ARRIVAL OF BETTER UPPER SUPPORT.

OUTLOOK...PRECIPITATION COVERAGE WILL REMAIN HIGH THROUGH
SUNDAY...THEN THE PATTERN WILL TRANSITION TO A MORE DIURNAL
PATTERN...BUT WITH CONTINUED MOISTURE IN THE AREA. RESTRICTIONS WILL
BE CONFINED MAINLY TO THUNDERSTORMS AND THEN EARLY MORNING STRATUS
WHERE HEAVY RAIN FELL THE PREVIOUS DAY.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       MED   78%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       LOW   55%     HIGH  92%     MED   64%     MED   63%
KAVL       HIGH  99%     HIGH 100%     HIGH  81%     HIGH  84%
KHKY       MED   64%     MED   70%     LOW   59%     MED   73%
KGMU       MED   79%     HIGH 100%     MED   69%     MED   65%
KAND       HIGH  85%     HIGH 100%     MED   77%     HIGH  93%

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...DEO
NEAR TERM...HG
SHORT TERM...WIMBERLEY
LONG TERM...DEO
AVIATION...HG


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