Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 241736

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
136 PM EDT TUE MAY 24 2016

High pressure will prevail over the Southeast most of this week. A
moist southerly flow will develop in mid week, which will
lead to warmer temperatures and mainly afternoon chances of showers
and thunderstorms each day through Friday.


As of 1045 AM Tuesday: No significant changes to the forecast for
the morning update. Main grid adjustments have been to reduce sky
cover through the day and adjust T/Td/winds based on recent obs
trends as well as near-term guidance.

Otherwise, upper ridging builds into the area today and tonight as
surface high pressure moves east across the area. This results in a
weak, but increasing southwesterly flow. Expect some ridge top
cumulus to develop during the afternoon, with mostly sunny skies
elsewhere. With thicknesses rising, highs today will top out near or
a little above normal. Any ridge top cumulus will dissipate with
loss of heating this evening. However, expect an increase in clouds
across the mountains overnight as a weak short wave moves through
the ridge and into the area. Forecast remains dry, with lows
dropping to near or a couple of degrees above normal. Patchy fog
will again be possible, but chance of widespread or dense fog is low.


As of 315 AM Tue: High pressure over the South Atlantic coast
will bring south to southwest return flow into the area Wed and
Thu. Diurnal instability will trend upward from day to day, driving
diurnal showers and thunderstorms. Subsidence will keep the Piedmont
sufficiently stable Wed, so PoPs are confined to the mountains then;
they expand to about the I-85 corridor Thu. Minimal shear implies
mainly disorganized pulse storms can be expected with localized
downbursts being the main threat besides lightning. Temps will
rise about a category above climo each day.


As of 300 AM Tue: The late week pattern will be dominated by a
broad upper ridge centered over the mid-Atlantic coast and sfc high
pressure. This by itself would result in rather run-of-the-mill
weather for late May, in which PoPs would be tied to diurnal
instability and temps at or a little above climo. However, the
proverbial fly in the ointment is what appears to be increasing
consensus for a tropical low to move into the Carolinas over
the weekend. Spread on the track thereof is still pretty wide
overall, but the 00z GFS and EC both show landfall near the Grand
Strand. They differ on its position thereafter. Winds do not appear
to be of concern on land at this point, but the nature of moisture
flux varies across the guidance spectrum, so it is difficult to
say whether PoPs would be greatly increased or decreased by the
presence of the system. It is difficult to make a model blend (for
grid production purposes) that does not reflect any influence from
it, though confidence on its track remains moderate at best. My
preferred choice of action at this point is to reflect PoPs only
slightly above climo, with mainly diurnal trends, but elevated
sky cover and slightly cooler temps Sun-Mon.


At KCLT and elsewhere: VFR through the period for the TAF sites,
though cannot rule out some brief fog in the southwest mountain
valleys toward sunrise Wednesday. Generally light SW winds (5kt or
less) through the period, near calm overnight. Will see intermittent
cirrus passing through the area, but otherwise SKC until Wednesday
midday when some low VFR Cu should develop across the area.

Outlook: Mainly VFR conditions will prevail through the week, but
patchy morning fog chance continues at KAVL. Scattered afternoon
SHRA/TSRA may return Wednesday afternoon, with daily coverage
increasing Thursday and Friday.

Confidence Table...

            17-23Z        23-05Z        05-11Z        11-12Z
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 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:




SHORT TERM...Wimberley
LONG TERM...Wimberley
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