Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 301746
AFDGSP

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

.SYNOPSIS...
WEAK SURFACE HIGH PRESSURE WILL LINGER ATOP THE REGION FOR THE NEXT
SEVERAL DAYS. MOISTURE OF VARYING DEGREES FROM THE REMANTS OF
TROPICAL CYCLONE ERIKA WILL CONTINUE TO SPREAD NORTH OVER THE AREA.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 140 PM EDT SUNDAY...MOIST UPGLIDE CONTINUES TO PREVAIL ACROSS
THE REGION YIELDING NUMEROUS/WIDESPREAD SHOWERS SOUTH OF THE
INTERSTATE 85 CORRIDOR...WITH ISOLATED/SCATTERED SHOWERS SPREAD
FURTHER NORTH.  STILL EXPECTING THIS TREND TO CONTINUE THROUGH
THE AFTERNOON/EVENING THEREFORE INCREASED POPS BOTH SPATIALLY AND
IN TIME YIELDING CAT LEVELS SOUTH OF INTERSTATE 85 THROUGH THE
AFTERNOON...TRANSITIONING TO LIKELY LEVELS EAST OVER THE INTERSTATE
77 CORRIDOR INTO LATE EVENING.  RATES REMAIN RATHER UNIMPRESSIVE
THEREFORE STILL NOT EXPECTING ANY FLOODING HAZARDS WITH THIS
PROLONGED PERIOD OF SHOWERS.  OTHERWISE...TWEAKED TEMPERATURES AND
DEWPOINTS TO BETTER ALIGN WITH RECENT OBS AND LEFT THE REMAINDER
OF THE FCST AS IT WAS.

AS OF 325 AM...A MID LEVEL LOW NEAR THE FL PANHANDLE THIS MORNING
WILL LIFT NORTHWARD TODAY. AS THE LOW TRACKS NORTH...IT WILL WEAKEN
INTO A S/W...EXPECTED TO PASS OVER THE CWA TONIGHT. AS THE MID
LEVEL FEATURE APPROACHES THE WESTERN CAROLINAS...CLOUDS ACROSS
THE REGION WILL THICKEN AND LOWER ALONG WITH THE DEVELOPMENT OF
SCT SHOWERS.  LATEST RADAR IMAGES AND SFC OBSERVATIONS INDICATED A
FEW PATCHES OF SPRINKLES DRIFTING OVER THE LAKE LANDS. LATEST RUNS
OF THE NAM AND 4 KM WRF SHOW SPRINKLES REMAINING ACROSS THE REGION
THIS MORNING...WITH SHOWERS THIS AFTERNOON AND EVENING. FORECAST
SOUNDINGS SHOW CAPE VALUES REMAIN QUITE LOW ACROSS THE REGION THIS
AFTERNOON...I WILL FORECAST PRIMARILY SHOWERS. THE GFS INDICATES
THAT THE PERIOD OF GREATEST SYNOPTIC SCALE FORCING WILL LIKELY
OCCUR BETWEEN 0Z TO 6Z MON. DURING THIS PERIOD...THE CLOSED LOW
OR S/W WILL SLIDE ACROSS THE REGION...RESULTING IN A BELT OF
Q-VECTOR CONVERGENCE ACROSS THE CAROLINAS. I WILL FORECAST 30 TO
50 POPS DURING THE LATE AFTERNOON AND EVENING. THE COMBINATION OF
THICK CLOUD COVER AND SHOWERS SHOULD KEEP HIGHS ACROSS THE UPPER
SAVANNAH RIVER VALLEY LIMITED TO THE U70S...WITH MID 80S EXPECTED
ACROSS THE CLT METRO.

TONIGHT...THE MID LEVEL TROF WILL TRACK NE...FOLLOWED BE WEAK
HEIGHT RISES DURING THE LATE NIGHT HOURS. I WILL TREND POPS LOWER
AFTER MIDNIGHT...BUT REMAINING IN THE SCHC TO LCHC RANGE. LOW
TEMPERATURES ARE FORECAST TO RANGE FROM THE L60S ACROSS THE MTNS
TO THE UPPER 60S EAST.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 245 AM EDT SUNDAY...A WEAK UPPER LEVEL CLOSED LOW/TROUGH WILL
REMAIN ORPHANED OVER E TX THROUGH THE SHORT TERM PERIOD...WHILE A
BROADER UPPER RIDGE BUILDS OVER THE ERN CONUS THROUGH TUESDAY. UNDER
THIS UPPER RIDGE...WEAK SURFACE HIGH PRESSURE WILL LINGER ALONG THE
APPALACHIANS. THERE APPEARS TO BE IMPROVING CONSENSUS IN THE
NUMERICAL MODELS ON KEEPING THE DEEPER TROPICAL MOISTURE ASSOCIATED
WITH THE ERIKA REMNANTS SHUNTED SOUTH OF THIS SURFACE RIDGE...WITH
THE GREATEST MOISTURE CONFINED MAINLY FROM FL TO THE COASTAL
CAROLINAS MON THROUGH TUE. FOR OUR REGION...THIS MEANS CONTINUED
WEAK INSTABILITY IN VERTICAL PROFILES UNDER THE RIDGE...BUT WITH
PRECIPITABLE WATER VALUES GRADUALLY INCREASING. WILL CONTINUE TO
FEATURE MAINLY DIURNAL SCATTERED CONVECTION WITH MAX TEMPS SLOWLY
REBOUNDING TO NEAR CLIMO DESPITE THE CLOUD COVER.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 245 AM EDT SUNDAY...A VERY WEAK UPPER LEVEL FLOW PATTERN WILL
EXIST WED THROUGH SAT AS THE PERSISTENT GULF COAST TROUGH SLOWLY
MIGRATES EAST UNDER THE BROAD FLAT ERN RIDGE. ANY REMNANT ERIKA
CIRCULATION APPEARS TO MAKE LITTLE NWD PROGRESS THROUGH THE MEDIUM
RANGE...WITH THE ECM/NAM CAMP KEEPING THE REMNANT LOW CENTER NEAR
COASTAL GA/NE FL WHILE THE GFS CAMP IS FARTHER SW NEAR THE FL
PANHANDLE. THIS WILL MAKE FOR HIGHLY UNCERTAIN MOISTURE PROFILES
OVER THE REGION...WITH A SHARP GRADIENT IN PRECIPITABLE WATER LIKELY
FROM THE DRIER NRN MOUNTAINS TO THE MORE MOIST LOWER SE PIEDMONT.
ANY PREDECESSOR RAIN EVENT POTENTIAL FOR EARLY IN THE PERIOD NOW
APPEARS QUITE NEBULOUS GIVEN THE CURRENT WEAK STATE OF THE ERIKA
REMNANTS AND POSSIBILITY OF SOME DRIER AIR REINFORCING FROM NORTH
MID TO LATE WEEK IN THE SURFACE RIDGE. WILL CONTINUE THE CURRENT
FORECAST THINKING OF SLIGHTLY ABOVE CLIMO/MAINLY DIURNAL POPS WED
THROUGH SAT...WITH GRADUALLY CLIMBING TEMPERATURES IN THE ABSENCE OF
ANY STRONG SIGNAL FOR HEAVY RAINFALL.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AT KCLT...A MIXTURE OF VFR/MVFR AND POSSIBLY IFR THROUGH THIS TAF
CYCLE AS GULF/ATLANTIC MOISTURE CONTINUES TO BE ADVECTED NORTHWARD
BY WAY OF NORTHWARD MIGRATING MID/UPPER LOW.  INITIALIZED TAF VFR
WITH VCSH MENTION AS LIGHT RETURNS CONTINUE TO SPREAD NORTHWARD
ON RADAR WITH A 4HR TEMPO STARTING AT 20Z FOR LIGHT SHRA.
SHRA WILL PREVAIL FROM 00Z-03Z WHEN NAM/HRRR AGREE ON TIMING OF
PRECIPITATION OVER THE NC PIEDMONT WITH MODERATE SHOWERS POSSIBLY
YIELDING MVFR VISB.  CIGS THROUGH THIS ENTIRE PERIOD WILL START
OUT AT MID LEVELS...GRADUALLY LOWERING LOW VFR BY AROUND MIDNIGHT.
FROM THAT POINT GUIDANCE FAVORS DETERIORATING CONDITIONS AMONGST
THE MOIST PBL WITH MVFR CIGS FAVORED BY 03Z WITH POSSIBLE IFR
AROUND/AFTER MIDNIGHT.  GUIDANCE TRENDS HAVE BEEN AWAY FROM
IFR...HOWEVER NOT CONFIDENT ENOUGH TO COMPLETELY REMOVE ANY
MENTION THUS KEPT SCT008 IN TAF.  OTHERWISE...CONDITIONS WILL
IMPROVE TO LOW VFR AFTER DAYBREAK.  WINDS THROUGH THE TAF CYCLE
WILL INITIALIZE SOMEWHAT VARIABLE...ALTHOUGH TAF FEATURES SE WINDS.
THESE LIGHT SE WINDS WILL PREVAIL SHORTLY AFTER ISSUANCE...LASTING
THROUGH THE PERIOD PERHAPS CALMING OVERNIGHT.

ELSEWHERE...SIMILAR TO THAT OF KCLT ABOVE WITH SITES OUTSIDE OF
THE MTNS EXPERIENCING THE GREATEST CHANCES FOR PRECIPITATION THIS
AFTERNOON EVENING DUE TO THE TRACK OF THE MIGRATING MID/UPPER
LOW AND ANY SYNOPTIC SCALE FORCING TIED TO IT.  THUS...ALL SC
SITES FEATURE PREVAILING SHRA THIS AFTERNOON WITH KHKY HAVING A
TEMPO INCLUDED FOR SUCH.  TAF REMAINS DRY REGARDING ANY PREVAILING
PRECIP AT KAVL THEREFORE OPTED FOR VCSH ONLY THROUGH LATE EVENING.
OTHERWISE...EXPECTING SIGNIFICANT RESTRICTIONS IN THE MTNS THIS
EVENING AS THE PBL CONTINUES TO MOISTEN AND WINDS CALM.  THUS KAVL
TAF FEATURES MVFR/IFR CIGS WITH EVEN AN LIFR VISB AROUND DAYBREAK.
GUIDANCE ALSO FAVORED IFR/LIFR AT THE SC SITES...MAINLY IN THE
FORM OF CIGS THEREFORE THOSE WERE ALSO INCLUDED.  LOOKS AS IF KHKY
WILL SEE THE LEAST IMPACT OVERNIGHT HOWEVER STILL COULD EXPERIENCE
MVFR CIGS/VISB BY MORNING.  OTHERWISE...ALL TAFS ARE DRY BY MID
EARLY/MORNING WITH ALL CONDITIONS IMPROVING SLOWLY AFTER DAYBREAK
ON MONDAY.  WINDS WILL REMAIN LIGHT AND SOMEWHAT VARIABLE THIS
AFTERNOON...CALM OVERNIGHT...AND INCREASING OUT OF THE SOUTHEAST
BY LATE MORNING MONDAY.

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...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH  87%     HIGH  83%
KGSP       HIGH 100%     HIGH 100%     HIGH  87%     LOW   50%
KAVL       HIGH 100%     HIGH 100%     MED   77%     MED   75%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  83%
KGMU       HIGH 100%     HIGH 100%     HIGH  81%     HIGH  83%
KAND       HIGH 100%     HIGH  94%     HIGH  94%     MED   66%

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...HG
NEAR TERM...CDG/NED
SHORT TERM...HG
LONG TERM...HG
AVIATION...CDG


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