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Local forecast by
"City, St"
  
000
FXUS62 KGSP 310228
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1028 PM EDT SUN AUG 30 2015

.SYNOPSIS...
WEAK SURFACE HIGH PRESSURE WILL LINGER OVER THE REGION FOR THE NEXT
SEVERAL DAYS. MOISTURE OF VARYING DEGREES FROM THE REMNANTS OF
TROPICAL CYCLONE ERIKA WILL CONTINUE TO SPREAD NORTH ACROSS THE
SOUTHEAST THROUGH THE END OF THE WORK WEEK...WITH INCREASING CHANCES
FOR AFTERNOON SHOWERS AND THUNDERSTORMS.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 1025 PM...UPPER LOW ONLY SLOWLY MOVING EAST THIS EVENING. AS A 
RESULT THE WARM CONVEYOR BELT AND UPPER DIVERGENCE ALSO ONLY SLOWLY 
MOVING EAST. THE LATEST MESOSCALE MODELS SEEM TO HAVE FINALLY PICKED 
UP ON THIS TREND AND SHOW A SLOW EAST TO NE MOVEMENT OF THE AREA OF 
WIDESPREAD SHRA. HAVE ADJUSTED POP TO SHOW THIS TREND...BUT KEEP 
SOME SCT SHRA ACROSS THE WEST EARLY BEFORE DROPPING POP TO SLIGHT 
CHC BEHIND THE CONVEYOR BELT PRECIP. THIS ALSO KEEPS CAT TO LIKELY 
POP ACROSS THE I-77 CORRIDOR UNTIL NEARLY DAYBREAK BEFORE MOVING 
EAST. FORTUNATELY...RAINFALL RATES ARE NOT HEAVY WHICH IS KEEPING 
ANY FLOOD THREAT MINIMAL AT BEST. THE RESULT IS WIDESPREAD 
BENEFICIAL RAINFALL. DO NOT EXPECT ANY TSRA FOR THE REST OF THE 
NITE. STILL EXPECT LOW CLOUDS AND PATCHY DENSE FOG ACROSS THE AREA 
TONIGHT AND EARLY MONDAY. LOWS WERE GENERALLY ON TRACK...EVEN THOUGH 
THE TEMP AND DEW POINT TRENDS WERE WAY OFF WITH THE CLOUDS AND 
PRECIP IN PLACE. LOWS WERE ADJUSTED SLIGHTLY AS THE TEMPS AND DEW 
POINTS WERE ADJUSTED TO BETTER FIT THE CURRENT AND EXPECTED TRENDS. 

AS OF 750 PM...WARM CONVEYOR BELT AHEAD OF AN UPPER LOW MOVING 
TOWARD THE AREA THIS EVENING...ALONG WITH DIVERGENCE WITH AN UPPER 
JET STREAK...ARE BRINGING WIDESPREAD SHRA TO MUCH OF THE CWFA THIS 
EVENING. THE CONVEYOR BELT AND UPPER DIVERGENCE MOVE ACROSS THE AREA 
THIS EVENING AND EAST OF THE AREA OVERNIGHT. HAVE ADJUSTED POP FCST 
TO SHOW THESE TRENDS. THE WEAK INSTABILITY IN PLACE ACROSS THE AREA 
IS SLOWLY WANING WITH LOSS OF HEATING. HAVE KEPT ANY TSRA MENTION TO 
ISOLATED THIS EVENING THEN JUST SHRA OVERNIGHT. GUIDANCE IN GOOD 
AGREEMENT ON LOW CLOUDS AND PATCHY FOG FORMING OUTSIDE OF THE MTNS 
OVERNIGHT WITH PATCHY DENSE FOG DEVELOPING ACROSS THE MTN VALLEYS. 
HAVE INCLUDED THIS AS WELL. OVERNIGHT LOWS STILL LOOK ON TRACK...BUT 
TEMP AND DEWPOINT TRENDS NEEDED ADJUSTMENT DUE TO THE PRECIP AND 
CLOUDS.

AS OF 425 PM...UPDATED POP TO ACCOUNT FOR THE INCREASING COVERAGE 
ACROSS THE WRN CWFA AND BRIEF LULL OVER THE ERN AREAS. LITTLE  
INSTABILITY SEEN ACROSS THE AREA...BUT THERE IS SOME THUNDER ALONG 
THE CENTRAL SAVANNAH RIVER VALLEY. THEREFORE...HAVE LIMITED THUNDER 
TO ISOLATED FOR THE REST OF THE AFTERNOON INTO THE EVENING. TEMPS 
ARE RUNNING SIGNIFICANTLY COOLER ACROSS THE WRN PORTIONS DUE TO 
CLOUDS AND PRECIP...AND SLIGHTLY COOLER ACROSS THE EAST. HAVE 
UPDATED TEMP TRENDS TO ACCOUNT FOR THIS AS WELL.

AS OF 240 PM EDT SUNDAY...CLOSED UPPER LOW CONTINUES TO SLIDE
NORTHEAST ACROSS THE DEEP SOUTH THIS AFTERNOON YIELDING A BROAD
REGION OF GULF/ATLANTIC MOISTURE ADVECTION OVER NORTHEAST GA AND
THE CAROLINAS.  MID ATLANTIC HIGH PRESSURE THAT HAS BEEN SO DOMINATE
THE LAST FEW DAYS WILL STRUGGLE TO SURVIVE...HOWEVER ACCORDING TO
GUIDANCE...SHOULD DO JUST THAT.  MOIST UPGLIDE ATOP SAID SURFACE
RIDGE WILL CONTINUE THROUGH THE AFTERNOON/EVENING WITH DEEP LAYER
SYNOPTIC SCALE Q VECTOR CONVERGENCE SPREADING OVERHEAD.  THUS...THE
FCST FEATURES CLOUDY SKIES WITH CATEGORICAL POPS SOUTH...TAPERING
TO CHANCE POPS FURTHEST NORTH THIS AFTERNOON.  POPS WILL GRADUALLY
ROTATE AS SAID SYNOPTIC SCALE LIFT TIED TO THE UPPER VORTEX SLIDES
THROUGH THE NC PIEDMONT REGION TONIGHT THEREFORE LIKELY POPS ARE
FAVORED OVER BOTH THE NC/SC PIEDMONTS THIS EVENING BEFORE LOWERING
OVERNIGHT.  PATCHY FOG AND LOW STRATUS WILL PREVAIL OVERNIGHT BEFORE
BURNING OFF AFTER DAYBREAK ON MONDAY.  THE REMNANTS OF TROPICAL
CYCLONE ERIKA WILL PROVIDE SOME INFLUENCE ON THE WEATHER CLOSER TO
HOME ON MONDAY...BUT MAINLY IN THE FORM OF SOME MID/HIGH CLOUDINESS.
NEVERTHELESS...MODELS DO FAVOR ENOUGH INSTABILITY ON MONDAY TO
WARRANT AT LEAST CHANCE POPS ACROSS THE ENTIRE REGION...WITH THE
MTNS BEING THE MOST LIKELY PLACE FOR CONVECTION.  THAT SAID...POOR
LAPSE RATES ALOFT WILL LIMIT THE DEPTH OF SAID CONVECTION THEREFORE
NOT EXPECTING ANYTHING MORE THAN A FEW RUMBLES OF THUNDER AT BEST.
TEMPERATURES ON MONDAY WILL BE NEAR CLIMO LEVELS.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 230 PM EDT SUNDAY...UPPER WEAKNESS OVER THE SOUTHERN PLAINS
WILL CONTINUE TO WEAKEN AS RIDGING CONTINUES TO BUILD OVER MOST OF
THE COUNTRY. A WEAKNESS WILL CROSS THE OHIO VALLEY THROUGH THE SHORT
TERM BUT ANY INFLUENCE FROM IT SHOULD STAY JUST TO OUR NORTH UNTIL
THE END OF THE PERIOD WHEN THE ASSOCIATED FORT MAX DIVES SOUTH
TOWARD THE CAROLINAS...ROTATING AROUND THE UPPER RIDGE. MEANWHILE
THE REMNANTS OF ERIKA ARE NOW PROGGED TO STAY TO OUR SOUTH AND
GRADUALLY DISSIPATE. SHOULD SEE A GRADUAL INCREASE IN PW VALUES BUT
REMAINING BELOW 2 INCHES...AND FOR THE MOST PART BELOW 1.75 INCHES.
HAVE CONTINUED TREND OF MAINLY DIURNAL POPS THROUGH THE SHORT TERM
AND SHOWING A SLIGHT WARMING TREND AS WELL...CLOSER TO SEASONAL
HIGHS...TO ACCOUNT FOR LESS AVAILABLE MOISTURE IN THIS FORECAST
CYCLE THAN PREVIOUSLY SHOWN. BETTER CHANCE FOR CONVECTION WEDNESDAY
AFTERNOON THAN TUESDAY JUST DUE TO THE APPROACHING UPPER VORT
MAX...BUT STILL ONLY CHANCES AT BEST /AND BEST CHANCES LIMITED TO
THE MOUNTAINS/.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 245 PM EDT SUNDAY...UPPER RIDGING WILL BEGIN TO WEAKEN INTO
THE EXTENDED AS A SHORTWAVE ALOFT DIVES DOWN THE NORTHWEST FLOW ON
THE EASTERN EDGE OF THE UPPER RIDGE...BRINGING A SLIGHT INCREASE IN
DIURNAL CONVECTION CHANCES AS WE MOVE INTO THE EXTENDED. STILL SOME
UNCERTAINTY AS TO WHAT THE REMNANTS OF ERIKA WILL DO BUT BOTH THE
GFS AND ECMWF HAVE THE MOISTURE SPREADING ACROSS THE DEEP SOUTH
TOWARD THE END OF THE WEEK...WITH INCREASING PW VALUES INTO THE
WEEKEND /HOVERING JUST UNDER 2 INCHES AT LEAST ON THE GFS/. 12Z
ECMWF IS MORE ROBUST WITH THE MOISTURE THAN THE GFS BUT BOTH BRING
DECENT QPF VALUES...ESPECIALLY ON SATURDAY AS THE WAVETRAIN SLIDES
EAST AND VERY VERY WEAK SOUTHWEST FLOW DEVELOPS AS THE RIDGE AXIS IS
MORE OVER THE WESTERN ATLANTIC THAN THE APPALACHIAN SPINE.
HOWEVER...CONTINUED TO KEEP POPS AT CHANCE AT BEST FOR NOW JUST
BECAUSE WE ARE LOOKING SEVERAL DAYS OUT AND QUITE A BIT COULD STILL
CHANGE BETWEEN NOW AND THEN. TEMPERATURES FAIRLY CLOSE TO SEASONAL
NORMALS.

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
AT KCLT...AN AREA OF SHRA WILL MOVE NORTH ACROSS THE AIRFIELD THIS 
EVENING. THIS WILL RESULT IN MVFR VSBY AND POSSIBLY LOW VFR CIGS. 
HAVE INCLUDED AS A TEMPO GIVEN THE VARIABLE NATURE OF THE PRECIP 
RATES. EXPECT A RETURN TO VFR SHRA AS THE HEAVIER SHOWERS MOVE EAST 
OF THE AREA. GUIDANCE IN GOOD AGREEMENT ON LOW CIGS DEVELOPING 
OVERNIGHT. HAVE GONE WITH MVFR THEN IFR TOWARD DAYBREAK IN MVFR FOG. 
COULD SEE THICKER FOG AS WELL...BUT CIGS SEEM MORE CERTAIN. THE CIGS 
SLOWLY LIFT THRU MVFR AFTER DAYBREAK TO LOW VFR BY EARLY AFTERNOON. 
GUIDANCE SHOWS SCT TSRA DEVELOPING DURING THE AFTERNOON...SO HAVE 
INCLUDED PROB30 FOR THAT TIME. SELY WINDS THIS EVENING BECOME ENE 
OVERNIGHT AND REMAIN THERE THRU THE DAY MONDAY.

ELSEWHERE...SIMILAR TO KCLT...EXCEPT THAT RESTRICTIONS IN SHRA WILL 
END SOONER. EXPECT MVFR TO IFR CIGS WITH MVFR VSBY AS WELL. KAVL 
WILL SEE IFR VSBY AND CIGS WITH VLIFR LIKELY TOWARD MORNING. 
RESTRICTIONS WILL SLOWLY INCREASE THRU MVFR TO VFR THRU THE MORNING 
MONDAY. CONVECTION MORE LIKELY AT KHKY FOR THE AFTERNOON...SO PROB30 
ONLY INCLUDED THERE. WINDS WILL SHOW SIMILAR TRENDS...EXCEPT KAVL 
WHERE SLY WIND BECOMES CALM THEN NLY.

OUTLOOK...THE SOUTHEAST REGION IS FORECAST TO REMAIN UNDER A PLUME
OF GULF AND ATLANTIC MOISTURE THROUGH THE MIDDLE OF NEXT WEEK. IN
ADDITION...MOISTURE ASSOCIATED WITH THE REMNANTS OF ERIKA COULD
REACH THE SOUTHERN APPALACHIANS DURING THE MID WEEK. RESTRICTIONS
ARE POSSIBLE DURING PERIODS OF RAIN AND WITH THE MTN VALLEY FOG
AROUND DAWN.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-00Z 
KCLT       HIGH  84%     HIGH  89%     HIGH  85%     HIGH 100%     
KGSP       HIGH  87%     LOW   55%     MED   78%     HIGH 100%     
KAVL       HIGH  83%     LOW   54%     MED   79%     HIGH 100%     
KHKY       HIGH  82%     LOW   52%     MED   66%     HIGH 100%     
KGMU       HIGH  86%     MED   64%     MED   75%     HIGH 100%     
KAND       HIGH  90%     LOW   57%     MED   74%     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

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...CDG/RWH
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...RWH


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Weather Forecast Office Greenville-Spartanburg
GSP International Airport
1549 GSP Drive
Greer, SC 29651
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Page last modified: January 20, 2010

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