Area Forecast Discussion
Issued by NWS Greer, SC

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267
FXUS62 KGSP 250735
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
335 AM EDT WED MAY 25 2016

.SYNOPSIS...
High pressure will prevail over the Southeast most of this
week. Moist southerly flow will lead to warmer temperatures and
mainly afternoon chances of showers and thunderstorms each day
through Friday. A period of cooler and wetter weather may develop
late in the weekend as low pressure moves onshore from the Atlantic.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 305 AM: Area of mid clouds trapped under a weak subsidence
inversion will move east of the area or scatter out around daybreak.
Another area of mid and high clouds will begin spreading into the
mountains around that time ahead of a weak short wave moving toward
the area. Southwesterly low level flow will bring increasing
moisture and warmth to the area today. This will lead to weak
instability across the mountains this afternoon. Isolated to
scattered convection will develop across the mountains this
afternoon then diminish during the evening. Forecast soundings show
a capped atmosphere or very high LFC levels outside of the mountains
today. The synoptic scale guidance is in good agreement on this
scenario. Some of the convection allowing models show a line of
convection developing to our west ahead of the aforementioned weak
short wave. This convection moves into the mountains, including NE
GA and the Upstate, this afternoon and dissipates as it reaches the
foothills of the three states. For now, have followed the synoptic
model scenario given the weak short wave and weak instability.
Clouds will linger much of the night even as the convection wanes.
Highs today and lows tonight will be around 5 degrees above normal.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 245 AM Wed: Generally speaking, a western Atlantic ridge
will be the dominant feature over the Southeast Thursday and
Friday. Moist southerly low-level flow will continue. On Thursday
a broad warm front will extend from low pressure over the northern
Plains southeastward into the upper Ohio Valley and vicinity, but
unlike some previous runs there is no longer indication this will
enhance lift over our CWFA. Diurnal destabilization will result
in PoPs slightly above climo and extending to all zones. The
ridge deepens by Friday afternoon and lapse rates are not quite
as good, so chances are correspondingly lower then. Max temps will
be slightly above climo, and mins will be several degrees above.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 310 AM Wed: The upper pattern progresses little into the
weekend, with the Bermuda High holding back the central CONUS
trough. While this by itself would suggest a continuation of mainly
diurnal convection and near- or above-normal temps, the "wildcard"
in the forecast continues to be the track of low pressure moving
out of the Bahamas and toward the South Atlantic coast Saturday and
beyond. Global models continue to show poor run-to-run consistency
with this feature, but the latest consensus (if you can call it
that) suggests the low will approach the Charleston area. Some
guidance stagnates the low along the coast and eventually takes
it toward the Outer Banks; the GFS and some GEM Ensemble members
instead bring it onshore near the mouth of the Savannah River. While
most guidance suggests deeper tropical moisture spreading over the
Carolinas as the low approaches, they do so to varying degrees,
and the timing thereof is not agreed upon. For now, a blend of
favored guidance produces suppressed diurnal PoPs on Saturday as a
pocket of dry air swings over the area ahead of the low, but then
a slow but steady increase in chances from Saturday night into
Monday. Max temps will fall to a couple degrees below climo early
next week under mostly cloudy and damp conditions; this will keep
diurnal ranges limited and thus min temps will be well above climo.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: mid clouds trapped under a subsidence
inversion are spreading out across the area outside of the
mountains. Expect the BKN mid clouds to scatter out near daybreak as
cirrus moves in from the west. Cannot rule out some mountain valley
fog, but chance will increase if the high clouds move in slower than
expected. Expect cumulus to develop with heating after daybreak.
Isolated to scattered mountain ridge top convection will develop
through the afternoon then taper off during the evening. Confidence
too low for any mention at KAVL or the other airfields. SW winds
will increase in speed through the day, then taper off during the
evening.

Outlook: Mainly VFR conditions will prevail through the period, but
patchy morning fog chances continue at KAVL. Scattered afternoon
SHRA/TSRA coverage will increase Thursday through Friday - with more
uncertainty on Sat.

Confidence Table...

            07-13Z        13-19Z        19-01Z        01-06Z
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 100%
KHKY       High 100%     High 100%     High 100%     High 100%
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 schedule TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:

www.weather.gov/gsp/aviation

&&

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

&&

$$
SYNOPSIS...Wimberley
NEAR TERM...RWH
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...RWH



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