Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 221932
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
332 PM EDT Tue May 22 2018

.SYNOPSIS...
High pressure will remain to the east through Friday while a trough
of low pressure lingers to the west. Developing low pressure
over the Gulf of Mexico will slowly move north this weekend
through early next week, potentially maintaining wet weather.

&&

.NEAR TERM /THROUGH TONIGHT/...
Diurnally driven showers/tstms will diminish quickly by late
afternoon/early evening as the sea breeze pushes west of the
forecast area and instability wanes with the loss of
insolation. Some showers may linger across the far interior an
hour or so after sunset, otherwise expect mainly dry conditions
to prevail for the overnight period. Some isolated showers
could form over the Atlantic closer to the west wall of the
Gulf Stream, but these are not expected to move onshore. Mostly
cloudy/partly sunny skies will give way to partly cloudy
conditions later this evening as debris cloudiness thins and
diurnal cumulus diminishes. Any meaningful low-stratus looks to
set up well inland across the Midlands and central Georgia.
Shallow ground fog is likely again, but no meaningful impacts
are expected. Lows will range from the upper 60s inland to the
lower-mid 70s at the coast, beaches and Downtown Charleston.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
Atlantic high pressure will remain to the east while a weak
surface trough lingers inland. Aloft, the area will remain
between a ridge to the north and a trough to the south. Tropical
moisture will stick around for several more days, with PWATs in
excess of 1.75". Extensive cloud cover will limit surface based
instability during the period. We expect scattered to numerous
showers, especially during the afternoon hours away from the
coast which will be closer to the surface trough and thus better
convergence. Thunderstorms will be fairly isolated given the
limited instability, but high PWATs favor some locally heavy
rainfall.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
Not much pattern change late this week into early next week with
high pressure remaining to the east and and low pressure to the
west. Will be watching for potential tropical cyclone development in
the south-central Gulf of Mexico. Models have been fairly agreeable
lately that the low will track toward the north-central Gulf Coast
region this weekend. This pattern will continue to maintain a
tropical air mass across southeast SC/GA and lead to higher than
normal rain chances. Temperatures should stay near to above
normal.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
KCHS: VFR. Showers/tstms should remain west of the terminal.

KSAV: Showers/tstms should be at/around the terminal at the
beginning of the 18z TAF period. Activity should move quickly
west and northwest of the terminal by 19-20z. Otherwise, VFR.

Extended Aviation Outlook: A persistent tropical air mass will
lead to higher than normal rain chances through the weekend,
mainly each afternoon. Thunder chances will be relatively low
however. Some restrictions will also be possible from morning
low clouds and/or fog.


&&

.MARINE...
Tonight: No concerns as the region remains along the western
flank of Atlantic high pressure. South to southwest winds 10-15
kt will prevail with seas averaging 2-4 ft nearshore waters and
4-5 ft offshore waters. Isolated showers will be possible after
midnight, mainly closer to the west wall of the Gulf Stream.

Wednesday through Sunday: Broad Atlantic high pressure will
persist to the east through the weekend. Meanwhile, a weak
surface trough will exist inland through Friday, then surface
low pressure will move into the central Gulf coast region over
the weekend. Winds will remain onshore 15 kt or less through
Saturday afternoon, then potentially increasing to 15-20 kt
Saturday night and Sunday due to a tighter gradient. A modest
afternoon sea breeze will affect coastal areas each day.

&&

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

&&

$$



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