Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 262352
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
752 PM EDT Wed Jul 26 2017

.SYNOPSIS...
Broad low pressure will remain across far southern Southeast
Georgia through tonight. A weak cold front will stall over or
near Southeast South Carolina through Thursday. Another cold
front will move into the area this weekend, then likely stall
just offshore into early next week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
As of 745 PM: A few isolated showers remained across the
forecast area. The greatest coverage was over McIntosh County
and adjacent waters, a rounds of convection develops on the east
side of a mid level low. I will update the PoPs to lower values
north of the Savannah River through the late night hours, then
indicate an increase towards dawn.

Previous discussion:
To start, numerous/widespread showers and
thunderstorms across far southern counties will gradually
diminish and/or gradually shift south of the Altamaha River.
Here, likely/categorical POPs will diminish to chance POPs as we
transition into the evening. Until then, locally heavy rain
could occur. At most other locations farther north/west, slight
chance/chance POPs early will diminish to less than 15 percent
with no mention of precipitation for several hours especially
after dark.

Overnight, guidance suggests that northern/western locations
away from the coast will remain rain-free. South of I-16,
scattered showers/thunderstorms could persist into the overnight
and could even increase in coverage late due to the persistent
influence of a slow-moving upper low. Over coastal waters and
adjacent coastal counties, coverage of showers/thunderstorms
could also increase late tonight. Thus, chance POPs return
along the coast well after midnight.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
Troughing will prevail through the period. The deepest moisture is
likely through Thursday before a mid-level low weakens and shifts
southeast of the area and again Friday night into Saturday ahead of
an approaching cold front. The main concern this time period will be
the threat for severe storms, mainly late Friday into Friday night
as deep layer shear increases. At this time however the risk appears
low given that the storms should be arriving at night when
instability will be less. Temperatures will warm into Friday ahead
of the front before dropping again Saturday.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Deep moisture characterized by PWATS up to 2.0 inches will persist
over the Southeast United States Saturday night into Sunday while a
cold front slowly progresses south and eventually stalls just
offshore and/or south of the region. The pattern becomes more
difficult to predict early next week with some guidance suggesting
that the stationary front drifts back near the Southeast coast or
low pressure develops along it and lifts northeast along/near the
Southeast coast. Regardless of the outcome, it appears chances of
showers/thunderstorms will be possible early next week with greatest
precip coverage anticipated near coastal areas.

Temps will generally be a few degrees below normal this weekend and
early next week given extensive cloud cover and precip activity. In
general, temps should peak in the mid/upper 80s. Overnight lows will
range in the low/mid 70s.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
VFR conditions through the 0Z TAF period. Light east winds are
expected through late tonight, then becoming calm for KSAV by
7z. Spokes of mid level forcing may rotate around the center of
a low during the daylight hours Thursday. I will indicate PROB30
for TSRA at KSAV during the mid day and KCHS during the
afternoon.

Extended Aviation Outlook: VFR conditions should prevail into
Friday. Higher chances of flight restrictions should return late
Friday through Sunday as showers and thunderstorms occur with a
cold front that slowly progresses over the region.

&&

.MARINE...
Tonight: Wind direction could remain changeable to start, but
more uniform east winds 10 kt or less are still expected to
develop, accompanied by seas 1-3 ft. Thunderstorms could
produce locally hazardous conditions, including brief
waterspouts, especially later tonight.

Thursday through Monday: A cold front looks to stall near the SC
waters through Thursday and then dissipate before another cold front
moves into the area this weekend. Conditions are expected to remain
below Small Craft Advisory levels through the period. However, a
southwest/south flow could gust around 20 knots Friday night into
early Saturday until cold fropa occurs. Seas will build a bit, up to
4 ft near the Gulf Stream, before subsiding a bit over the weekend
as the front pushes through, and then increasing again early next
week behind the front.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.

&&

$$
NEAR TERM...NED/SPR
SHORT TERM...RJB
LONG TERM...
AVIATION...RJB/SPR
MARINE...RJB/SPR


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