Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 241128
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
728 AM EDT Tue Apr 24 2018

.SYNOPSIS...
Low pressure will cross the area today and will slowly move up
the east coast through mid week. An upper level disturbance
will move over the area Thursday night, followed by a cold
front late week or early this weekend. High pressure will then
build over the region through early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
A closed upper low spinning over Tennessee will start to make
some eastward progress today, while an associated surface low
drifts overhead. The persistent stream of showers that were
moving onshore over Charleston county overnight has finally
moved off the coast. Have kept 20-30% PoPs for the next couple
of hours, but largely precip is done as drier air works into the
area. Later in the day, couldn`t rule out a few showers far
inland with the upper low nearby, but models output very little
to no QPF so no more than slight chance PoPs are in the forecast
at this time. Cloud cover will continue to decrease this
morning, with partly to mostly sunny skies expected by the
afternoon. Temperatures will return closer to normal today with
highs in the upper 70s to around 80 away from the coast.

Tonight, the low pressure system will finally begin to slowly
lift northeast and away from the area. Little in the way of
cloud cover expected, but winds will likely stay a bit elevated.
Lows will be a few degrees above normal, mainly in the upper
50s to around 60.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
Wednesday: Low pressure at the surface and aloft will move away from
the region. Cannot completely rule out a shower or two across
northern counties but moisture appears insufficient to justify a
mention of precipitation. Expect high temps around 80F away from the
immediate coast. Temps Wednesday night will bottom out in the
mid/upper 50s inland and around 60F on the coast.

Thursday: An amplifying shortwave and associated surface low will
approach the region during the day and will cross the area at night.
Isolated/scattered showers could push into the region Thursday
afternoon, but highest POPs 30-35 percent south and 45-50 percent
inland/north should occur Thursday night. Cannot rule out isolated
thunderstorms with this system, but instability remains too limited
to justify any mention of thunder. Expect high temps in the
mid/upper 70s most inland locations, followed by low temps in the
lower-mid 50s inland and around 60F on the coast.

Friday: Isolated showers cannot be ruled out due to persistent
surface-850 mb troughing, so the latest forecast includes slight
chance POPs. However, models disagree regarding moisture, and a rain-
free day is entirely possible. Temps should top out close to normal
for late April, in the mid/upper 70s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
Forecast confidence remains low through Saturday. A longwave upper
trough and associated cold front will push through the region.
However, solutions range from progressive features crossing the
region within nothing more than a few showers to a deeper upper
trough and associated surface cyclogenesis producing more persistent
precipitation through Saturday. The latest forecast maintains a rain-
free forecast Saturday. Then, models agree that high pressure will
build at the surface and aloft over the region late weekend through
at least early next week, supporting dry weather and near to
slightly above normal temps.

&&

.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
Low ceilings will continue to scatter out this morning, with VFR
expected the remainder of the 12z TAF cycle.

Extended Aviation Outlook: Flight restrictions are possible
with showers late Thursday/early Friday. Otherwise, VFR.

&&

.MARINE...
Today into tonight: Winds have vastly dropped off as a warm
front shifted north of the waters and the pressure gradient
relaxed. South winds will gradually become more southwest as the
day progresses, with speeds 10-15 knots on average. Seas will
be slower to improve. Seas will drop below Small Craft Advisory
criteria for the southern two nearshore zones this afternoon.
6+ foot seas will continue through tonight in the Charleston
county waters and outer GA waters.

Wednesday through Sunday: The last of the 6 ft/SCA seas should
retreat beyond the outer GA waters by early Wednesday afternoon.
Then, Small Craft Advisory conditions are not expected through this
weekend. Synoptic wind direction will change with time, with
offshore winds becoming SW Wednesday then SE Thursday, followed by
SW winds Friday, offshore winds Saturday and NE winds Sunday.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 5 PM EDT this afternoon for AMZ352.
     Small Craft Advisory until 2 PM EDT Wednesday for AMZ374.
     Small Craft Advisory until 7 AM EDT Wednesday for AMZ350.
     Small Craft Advisory until noon EDT today for AMZ354.

&&

$$
NEAR TERM...ECT
SHORT TERM...SPR
LONG TERM...SPR
AVIATION...ECT
MARINE...ECT/SPR



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