Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 071355
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
955 AM EDT TUE JUL 7 2015

.SYNOPSIS...
AN ELONGATED UPPER RIDGE WILL STRENGTHEN AND RETROGRADE OVER THE
SOUTHEAST THROUGH THE WEEKEND. SHOWER AND THUNDERSTORM CHANCES WILL
FAVOR THE AFTERNOON AND EVENING WITH THE BEST CHANCES RESIDING OVER
THE HIGH TERRAIN. TEMPERATURES WILL INCREASE TO ABOVE NORMAL LEVELS.

&&

.NEAR TERM /THROUGH TONIGHT/...
1000 EDT UPDATE...POPS AND QPF WERE REDUCED EARLY ON BASED ON RADAR
TRENDS. SKY OVER WAS UPDATED FROM VISIBLE SATELLITE IMAGERY. WINDS
WERE UPDATED TO INCORPORATE THE LATEST NAM DATA.

AS OF 630 AM...SOME DENSE FOG HAS FORMED NEAR ANDERSON POSSIBLY DUE
TO ENHANCED MOISTURE COMING OFF LAKE HARTWELL IN LIGHT SW FLOW. THE
FOG LAYER IS THICK ENOUGH THAT IT MAY TAKE UNTIL 8 OR 9 A.M. TO
FULLY CLEAR UP. PATCHY LIGHT FOG IS SEEN AROUND MUCH OF THE
REMAINDER OF THE AREA...BUT THIS SHOULD IMPROVE MORE QUICKLY. IN
LIGHT OF LATEST HRRR RUNS AND RESULTS FROM 00Z NCAR WRFDART
ENSEMBLE...FEEL A BIT MORE CONFIDENT ABOUT SCT SHRA/TSRA DEVELOPING
LATE MRNG OVER THE ESCARPMENT...BUT THE EXISTING COVERAGE WORDING
STILL LOOKS GOOD.

AS OF 300 AM...AN ACTIVE NORTHERN STREAM WILL CONTINUE TODAY...AS A
SHORTWAVE CROSSES THE GREAT LAKES AND A COLD FRONT TRAILS IT INTO
THE MID MISSISSIPPI AND OHIO VALLEYS. HOWEVER OUR WEATHER WILL
MAINLY BE UNDER THE CONTROL OF THE BERMUDA HIGH...WITH TEMPS PEAKING
A COUPLE DEGREES ABOVE NORMAL...AND SOUTHWESTERLY WINDS. DIURNALLY
DRIVEN CONVECTION WILL DRIVE POPS. NAM AND EVEN GFS CAPE PROGS WOULD
SUGGEST FAIRLY WIDESPREAD ACTIVITY...BUT IN THE RECENT DAYS THEY
HAVE BEEN OVERDONE IN TERMS OF CONVECTIVE EXPECTATIONS. THE HI-RES
SPC AND NSSL WRFS SHOW SCATTERED ACTIVITY DEVELOPING OVER THE BLUE
RIDGE ESCARPMENT AT MIDDAY...BUT STRUGGLING TO PROPAGATE EAST INTO
THE PIEDMONT WHERE SUBSIDENCE WILL KEEP WARMER TEMPS ALOFT. POPS
WILL BE CONFINED GENERALLY TO THE BLUE RIDGE AND FOOTHILLS. DRY AIR
IN THE MID-UPPER LEVELS WILL ALLOW ANY TSTMS THAT DO FORM TO PRODUCE
FAIRLY GOOD DOWNBURSTS...THOUGH THE SEVERE THREAT IS NOT APPRECIABLE.

TONIGHT...THE COLD FRONT WILL HANG UP INVOF THE OHIO RIVER AS THE
SFC LOW PUSHES INTO ERN CANADA. LOW LEVEL FLOW WILL VEER A BIT OVER
THE GREAT TN VALLEY...AND SOME UPSLOPING INTO THE WNC MTNS MAY ALLOW
SOME CLOUD COVER TO DEVELOP. HOWEVER RAIN CHANCES REMAIN
UNMENTIONABLY LOW. MIN TEMPS WILL BE A FEW DEGREES ABOVE NORMAL
DESPITE MOSTLY CLEAR SKIES EAST OF THE MTNS.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 200 AM EDT TUESDAY...THE SHORT TERM FCST PERIOD INITIALIZES
WEDNESDAY MORNING AMIDST BUILDING SUBTROPICAL UPPER RIDGE OVER
SOUTHEAST...WHILE A SERIES OF WEAK H5 IMPULSES SLIDE THROUGH THE
MEAN QUASIZONAL FLOW OVER THE MIDWEST AND MID MISSISSIPPI RIVER
VALLEY.  AT THE SURFACE...BERMUDA HIGH PRESSURE WILL BE WELL
ESTABLISHED OVER THE WESTERN ATLANTIC LEADING TO PREVAILING
SOUTHERLY FLOW INTO THE THE SOUTHERN APPS.  A COLD FRONT WILL
EXTENDED SOUTHWARD FROM QUEBEC ALONG THE CENTRAL/NORTHERN
APPS...BEFORE TURNING WESTWARD ATOP THE OHIO RIVER VALLEY INTO THE
CENTRAL PLAINS.

AS THE PATTERN EVOLVES ON WEDNESDAY MODELS SUGGEST THE ABOVE
MENTIONED COLD FRONT WILL SAG FURTHER SOUTH...HOWEVER SHOULD REMAIN
NORTH OF THE CWFA...LIKELY DRAPED ACROSS CENTRAL VA/KY.  UPPER
HEIGHTS WILL BE ON THE RISE ACROSS NORTHEAST GA AND THE WESTERN
CAROLINAS AS THE ELONGATED UPPER RIDGE CONTINUES ITS RETROGRESSION
WESTWARD.  ALL SAID...SOUNDINGS LOOK FAIRLY UNFAVORABLE FOR
CONVECTION ALONG AND EAST OF I77 WHERE HEATING WILL ALLOW FOR
ABUNDANT INSTABILITY...BUT LIKELY REMAIN CAPPED.  POINTS FURTHER
WEST WILL SEE INCREASING PRECIP CHANCES DUE TO WEAKER
SUBSIDENCE...HOWEVER THOSE CHANCES WILL REMAIN RATHER LOW EXCEPT FOR
OVER THE NC HIGH TERRAIN.  THEREFORE...LOW END SLIGHT CHANCE POPS
ARE FEATURED ALONG THE I85 CORRIDOR...WITH AN INCREASING GRADIENT TO
CHANCE POPS ACROSS THE BLUE RIDGE.  PROFILES ARE MARGINALLY UNSTABLE
ACROSS THE MOUNTAINS WITH LITTLE IN THE WAY OF CIN TO PREVENT
INITIATION DURING PEAK HEATING.  THUS FOR THE MTNS...WOULD NOT BE
SURPRISED TO SEE A FEW STRONG STORMS WITH DAMAGING WINDS AND HAIL
BEING THE PRIMARY THREATS.

EXPECTING LESS COVERAGE OVER THE FCST AREA ON THURSDAY AS ZONAL FLOW
TO THE NORTH PREVENTS ANY UPSTREAM MCS ACTIVITY ASSOCIATED WITH A
SERIES OF H5 WAVES FROM SLIDING SOUTHWARD INTO THE REGION.
ADDITIONALLY...UPPER HEIGHTS WILL HAVE RISEN FURTHER WITH THE CENTER
OF THE SUBTROPICAL RIDGE SETUP SOMEWHERE OVER THE SOUTHEAST STATES.
PROFILES ARE FAIRLY WARM LEADING TO POOR LAPSE RATES AND LITTLE IN
THE WAY OVER INSTABILITY...EVEN OVER THE HIGHER TERRAIN.  THUS FCST
POPS ARE NON MENTIONABLE OUTSIDE OF THE MOUNTAINS WHERE ONLY SLIGHT
CHANCES PREVAIL.  TEMPERATURES THROUGH THE SHORT RANGE WILL
GRADUALLY INCREASE WITH HIGHS TOPPING OUT A COUPLE DEGREES ABOVE
NORMAL ON WEDNESDAY...WITH HIGHS AROUND 4-5 DEGREES ABOVE NORMAL ON
THURSDAY.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 AM EDT TUESDAY...THE MEDIUM RANGE FCST PERIOD INITIALIZES
FRIDAY MORNING WITH A 592DM H5 RIDGE SLIDING ACROSS THE DEEP
SOUTH...WHILE THE FIRST IN A SERIES OF SHORT WAVE IMPULSES SLIDES
THROUGH THE MID MISSISSIPPI AND OHIO RIVER VALLEYS.  AT THE
SURFACE...BROAD BERMUDA HIGH WILL DOMINATE THE FLOW OVER THE
SOUTHEAST WHILE AN OLD FRONTAL BOUNDARY MEANDERS OVER THE MID
ATLANTIC...EASTWARD INTO THE OHIO RIVER VALLEY.  GUIDANCE FAVORS
INCREASING POPS FRIDAY AND SATURDAY AS THE PATTERN EVOLVES TOWARD
BETTER ALIGNMENT FOR DIURNAL THUNDERSTORMS THANKS TO UPPER RIDGE
RETROGRESSION...ALONG WITH POSSIBLE MCS PROPAGATION AS ACTIVITY
FIRES ALONG THE ABOVE MENTIONED FRONTAL AXIS BENEATH SAID UPPER
IMPULSES.  THEREFORE...POPS ARE FEATURED AT SLIGHT CHANCE LEVELS
OVER THE PIEDMONT REGIONS WHILE THE MOUNTAINS FAVOR CHANCE POPS EACH
DAY.  BY SUNDAY THE UPPER RIDGE WILL HAVE SHIFTED OUT OVER THE
SOUTHERN PLAINS LEADING TO CONTINUAL/WEAK HEIGHT FALLS ALOFT.  WITH
THAT SAID...MODELS FAVOR LESS UPPER WAVE ACTIVITY AROUND THE TOP OF
THE RIDGE ON SUNDAY...THEREFORE POPS ARE ALLOWED TO LOWER TO BELOW
CLIMO.  POPS WILL RETURN TO CLIMO LEVELS ON MONDAY AS MODELS PROG
ANOTHER...PERHAPS MORE ORGANIZED UPPER WAVE MOVING THROUGH THE OHIO
VALLEY INTO THE CENTRAL/SOUTHERN APPS.  TEMPERATURES THROUGH THE
PERIOD WILL REMAIN ABOVE NORMAL LEVELS.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
AT KCLT AND ELSEWHERE...PATCHY MRNG FOG WILL DISSOLVE QUICKLY AFTER
12Z AT ALL SITES WITH THE EXCEPTION OF KAND...WHERE THE LAYER IS
THICK ENOUGH THAT A LIFR CIG IS REPORTED. OTHERWISE SOLAR HEATING
SHOULD BE PRETTY EFFECTIVE IN IMPROVING VSBYS. BEYOND THIS MRNG...A
PRETTY QUIET PERIOD IS IN STORE WITH MAINLY SWLY WINDS...BUT KAVL
WILL START OFF NLY AND FLIP AT MIDDAY. A FEW SHRA AND PERHAPS A
COUPLE TSRA WILL DEVELOP ALONG THE BLUE RIDGE AROUND MIDDAY...BUT
STAND LITTLE CHANCE OF SURVIVING THE TRIP EAST INTO LESS FAVORABLE
AIR. KAVL HAS A VCSH MENTION BUT OTHER SITES ARE DRY.
TONIGHT...CONDITIONS SHOULD BE A BIT DRIER WHICH WILL LIMIT THE FOG
COVERAGE...THOUGH MTN VALLEYS AND SITES IN THE NRN CATAWBA VALLEY
STILL LOOK TO SEE SOME RESTRICTIONS. A FEW LOW VFR CLOUDS WILL
DEVELOP OVER THE MTNS BUT OTHERWISE SKIES WILL BE NEARLY CLEAR.

OUTLOOK...ISOLATED TO SCATTERED AFTN/EVENING THUNDERSTORMS ARE
EXPECTED OVER THE AREA THRU THIS WEEKEND...MAINLY IN THE MTNS...WITH
ASSOCIATED RESTRICTIONS UNDER THE HEAVIEST SHOWERS. LOW CLOUDS AND
FOG COULD DEVELOP IN THE MORNING AT PLACES THAT HAVE SHOWER ACTIVITY
THE DAY BEFORE.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  95%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  91%
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...CDG
NEAR TERM...JAT/WIMBERLEY
SHORT TERM...CDG
LONG TERM...CDG
AVIATION...WIMBERLEY



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