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000
FXUS62 KCHS 210436
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1236 AM EDT Sun Apr 21 2024

.SYNOPSIS...
An area of low pressure and associated front will pass through
the area and offshore tonight through Sunday. Dry high pressure
will return to the region early next week and prevail into the
middle of the week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
KCLX shows a southward moving outflow boundary moving into
Berkeley County, generated by convection over the Pee Dee. This
feature has the best chance for producing showers/tstms over the
next few hours, mainly form Colleton County north to the Santee
River. South of this area, the atmosphere caps off pretty
quickly. Pops were reoriented to better reflect this.
Temperatures are proving tricky with the cold front still well
to the north. Lows from the lower 60s well inland to the upper
60s at the beaches were maintained, although many areas may very
well end up a few degrees warmer than that with a slower
southward progression of the cold front expected.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
Sunday and Sunday night: A tricky forecast as the cold front will be
situated directly across the forecast area from west-southwest to
east-northeast. The first part of the day should be in a relative
lull for showers and/or thunderstorms in the wake of departed early
Sunday morning convection. The front will slowly sag southward
across the area through the day and increased rain chances are
expected for the afternoon and especially into the evening as the
area gets into the cool side of the low and the front. While there
could be a few hours of sufficient instability for thunderstorms in
the morning just about anywhere, the risk area will steadily shrink
southward to primarily include the I-16 corridor and south including
Jasper and Beaufort counties. The greatest coverage of mostly
showers will track across the area from the late afternoon through
the late evening hours and that is when we have the highest rain
chances in place. Overall, the severe threat is low as the best
instability is progged to retreat southward before the arrival of
the better forcing. However, it`s not out of the question to see a
couple of stronger storms across our far south including McIntosh,
Long, Liberty, and Bryan counties in the late afternoon and early
evening hours. Daytime highs will be quite the forecast challenge
thanks to the presence of the front and anticipated north to south
gradient. Inland areas across Millen to Allendale and Moncks Corner
might only reach the mid 60s while locations around Savannah,
Hinesville, and Darien reach the low to mid 80s. Overnight should be
mostly dry with the low and front situated offshore. Lows are
forecast to cool into the upper 40s inland and the low 50s closer to
the coast.

Monday through Tuesday: Monday will bring a seasonally cool day as
the area is situated between the high to the west and the low center
and associated front offshore. This setup will drive cool northeast
flow across the area and some model guidance that there will be
enough residual moisture to produce some light rain showers Monday
morning and early afternoon. We have kept 20 percent rain chances
for much of the day, mostly along the coastal corridor. Cloud skies
in the morning should start clearing from the west in the afternoon.
Temperatures will be the main story, with highs only topping out in
the mid to upper 60s which would be on the order of 11-13 degrees
below normal for the date. Then for Tuesday, high pressure settles
in across the area and temperatures are expected to rebound nicely
back into the mid 70s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Overall, the long term forecast period looks to be quiet with
temperatures rebounding to be back above normal for most of the
period. High pressure will be the primary feature during the period,
though what looks like a dry front will drop through from the north
during the Wednesday night-Thursday period.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
21/06z TAF Discussion:
KCHS/KJZI: Southward moving outflow boundary will cross the
terminals around 06z, resulting in either a variable or
northerly wind direction. This feature could produce a few
showers/tstms through about 08z, but the atmosphere is capping
off pretty quick ahead of the boundary. The risk for low clouds
appears to be delayed with the front still well to the north and
expected to progress much slower than expected. MVFR cigs are
anticipated by mid-morning with the risk for showers increasing
by early afternoon. IFR cigs with showers impacts will be
possible 20-23z, so TEMPO groups were utilized to account for
this at both sites. Widespread IFR cigs are expected from late
afternoon through the remainder of the 06z TAF period.

KSAV: VFR will dominate through late morning with the
approaching cold front expected to remain to the north through
then. Showers/tstms will increase ahead of the front, which
could impact the terminal 19-22z. A TEMPO group for MVFR
vsbys/cigs in TSRA was utilized to account for this. Showers
may linger near the terminal through about 00z which should end
as the front passes through. Widespread IFR cigs are expected
from roughly sunset through the remainder of the 06z TAF period.

Extended Aviation Outlook: Flight restrictions will likely
linger across the area from Sunday evening through the first
part of Monday before improving. VFR thereafter.

&&

.MARINE...
Tonight: A cold front will slowly sink to the south and
southeast through the night, reaching into the Charleston County
waters late. In advance of the front SW winds will reach as high
as 15 or 20 kt, then winds clock around to the W south of the
front, maybe around to the NW and N on the Charleston waters
late, with speeds dropping to about 10 kt or under. Seas will
average 2 or 3 feet. Mariners should remain alert for some
t-storms developing on the Charleston County waters after
midnight. Wind gusts of 30 or 35 kt and frequent lightning can
occur with some of these storms.

Sunday through Thursday: Winds will start to surge out of the north
Sunday afternoon as a front clears through the waters. Northeast
flow will then strengthen Sunday night through most of Monday and
Small Craft Advisories will very likely be needed for all the local
waters. Conditions will then steadily improve through Tuesday with
no forecast concerns through the end of the forecast period.

&&

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

&&

$$