Area Forecast Discussion
Issued by NWS Charleston, SC
FXUS62 KCHS 240610
Area Forecast Discussion
National Weather Service Charleston SC
110 AM EST Tue Jan 24 2017
An area of low pressure will lift northeast away from the area
tonight. High pressure will then prevail through Wednesday
before a cold front pushes through early Thursday. Cooler high
pressure will then return into the weekend.
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Surface low pressure south of Long Island in tandem with it`s
mid level low near the Delmarva will move further NE overnight.
However, their large cyclonic flow will extend back across the
local area. Aside from one last spoke of vorticity that will
generate scattered stratocumulus near and north of I-26, skies
will be clear. The dry air mass and cold advection will allow
for lows down into the mid or upper 40s. Steady isallobaric
pressure rises will keep the boundary layer stirred enough that
W-NW winds will average 10-15 mph and occasionally gusty,
producing wind chills a few degrees colder than the actual air
Lake Winds: The observation site at Pinopolis is not sampling
the winds well enough to be representative enough of speeds on
Lake Moultrie. Thus with steady isallobaric pressure rises
overnight we still feel that gusts to 25 kt over the exposed
portions of the lake will occur. So the Lake Wind Advisory stays
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/...
High pressure to build in behind departing low pressure Tuesday
leading to diminishing winds. The high is expected to slide off to
the south and east Wednesday ahead of an approaching cold front,
which should push through southeast SC/GA Thursday morning with some
showers. Clearing, but cooler and breezy conditions will then settle
in for Thursday afternoon. Temperatures will be on a warming trend
through Wednesday night before cooling down on Thursday.
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
The long term period will be fairly quiet with high pressure to
persist late week through much of the weekend. A dry backdoor cold
front could then drop south into the area early Monday. No
mentionable PoPs are in the forecast at this time. Perhaps the most
notable feature of interest will be the return of cooler, more
seasonable temperatures after an extended warm period. Highs will
generally be in the 50s, with lows in the 30s.
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
VFR through 06Z Wednesday. A tight gradient and cold advection
prior to daybreak, then deeper mixing during the daylight hours
Tuesday will lead to gusty W-NW winds at both terminals. Winds
will then diminish quickly around sunset.
Extended Aviation Outlook: VFR through Saturday, although
breezy/gusty conditions likely Thursday through Saturday, mainly
during the afternoon.
Tonight: Pressure rises of 1-2 mb/3 hour, cold advection and a
tight cyclonic gradient around low pressure south of Long Island
will cause elevated winds throughout the overnight. Plenty of
those 30-35 kt geostrophic winds will occur in this pattern,
leading to a continuation of the Gale Warnings for the GA
waters, and SCA`s on the SC waters. Seas will be limited closer
to shore by the offshore, but trending upwards to near 4 or 5 ft
out near 20 nm and 6-8 ft on the outer GA waters.
Tuesday through Saturday: High pressure will build in behind
departing low pressure Tuesday leading to lessening winds and thus
seas as well. The risk for gale force gusts, mainly across the GA
waters, will end Tuesday morning, although Advisory conditions will
likely hang on into early afternoon. Across the near shore waters
Advisory conditions should end by the afternoon. Conditions will
then go downhill again Wednesday as a cold front approaches and then
finally passes through early Thursday. Advisory conditions will be
likely beyond 20 nm and across the Charleston County near shore
waters Wednesday night and Thursday. Winds will remain elevated
through the end of the week, possibly again reaching Advisory levels
mainly across the Charleston near shore and Georgia offshore waters.
SC...Lake Wind Advisory until 4 AM EST early this morning for
MARINE...Small Craft Advisory until 10 AM EST this morning for AMZ350-
Gale Warning until 7 AM EST this morning for AMZ354-374.
Small Craft Advisory until 7 AM EST this morning for AMZ330.