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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KCHS 300731
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
331 AM EDT Mon Mar 30 2020

.SYNOPSIS...
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A cold front will pass offshore early this morning, and is
followed by a weak pressure pattern today into tonight. Low
pressure will then cross the area Tuesday into Tuesday night,
followed by high pressure for mid to late week.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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Pre-dawn: A weak and dry cold front will pass into the ocean,
accompanied by scattered-broken stratocumulus, and scattered-
broken cirriform clouds. Given that there isn`t much in the way
of cool air behind the front, temps will begin the day far above
climo.

For today: The cold front will eventually stall out near the
Georgia/Florida line, with a weak surface pressure pattern in
place across the local area. A trough to the lee of the
Appalachians will support a deep and dry west-southwest flow,
while a zonal flow dominates aloft. As mixing heights climb
throughout the day, dew points will plummet into the 40s inland
from the coast. With a weak downslope flow, a dry lower and
middle atmosphere and 850 mb temps that are 14-15C, we look for
max temps to peak in the lower 80s northwest and north tier,
with mid and upper 80s most elsewhere inland from the immediate
coast. We didn`t go quite as warm as the "pure" low level
thickness forecast since there will be varying amounts of broken
cirriform clouds traversing the area.

Tonight: A stationary front will remain to the south, as low
pressure travels quickly eastward from northern Texas into the
lower Mississippi Valley. To the north we find the southern
extension of high pressure poking in late from the lee of the
mountains. Mid and high level clouds will steadily increase, so
we didn`t go as low for temps as the MOS guidance would
suggest, equating to min temps that are close to 10F above
normal.
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&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
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Tuesday will be the most active day of the coming week. A potent mid
level trough will swing into the eastern U.S. through the day. As
this occurs, surface low pressure will approach from the west and
eventually track over the area in the afternoon and evening.
Increasing moisture (noted by PWats of over 1.6 inches) and forcing
for ascent will provide focus for showers and some thunderstorms.
Most areas are expected to receive a half of an inch of rain on
average through the event. Attention then turns to the severe
weather potential. 0-6 km shear is over 50 knots, which will
certainly promote storm organization. The limiting factor will be
the instability. Mid level lapse rates are unimpressive and CAPE
values are marginal. The most favorable ingredients will be across
Georgia zones, especially south of I-16, which is where SPC Day 2
Outlook highlights a Slight Risk of severe weather. Areas further
north near the Charleston tri-county will reside in a more stable
environment, so the severe threat will be lesser. The primary threat
within strong/severe storms are damaging wind gusts and perhaps a
tornado. Otherwise, temperatures will peak in the 70s, around 80
near the Altamaha.

The bulk of rainfall will push off the coast late Tuesday evening,
with any lingering showers diminishing by Wednesday morning as drier
air filters in. Cold advection will bring lows closer to normal.

The low will pull away from the area on Wednesday as high pressure
expands into the region. Residual low level moisture will keep
clouds around for the first part of the day, but cloud cover will
diminish with time. Noticeably cooler temperatures are expected,
with highs peaking in the mid to upper 60s. Lows Wednesday night
near normal.

High pressure will persist through Thursday. Dry conditions are
expected with plenty of sunshine. Highs will range from the upper
60s in the north to mid 70s south.
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&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
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Relatively quiet weather expected late week into the weekend as high
pressure remains the dominant feature. A couple models hint that a
weak front could approach/cross late in the period, but this has
been trending later each day. Rain chances overall will remain
pretty low, but as moisture returns over the weekend a few showers
can`t be ruled out. Temperatures will be near to slightly above
normal.
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&&

.AVIATION /07Z MONDAY THROUGH FRIDAY/...
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VFR through 06Z Tuesday at both CHS and KSAV.

Extended Aviation Outlook: Flight restrictions in low clouds and
showers/thunderstorms are likely Tuesday evening into Tuesday night
as low pressure crosses the area. VFR is expected to return
Wednesday morning and will prevail through late week.
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&&

.MARINE...
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Today: A cold front will pass into and through the waters before
daybreak, and is followed by weak high pressure throughout the
upcoming day. Winds will become W-NW at no more than 10 or 12 kt
for the daylight morning hours, before light sea breeze influences
develop in the afternoon. Seas will average 2 or 3 ft.

Tonight: We find the front wavering near the Florida waters in
advance of low pressure moving through Texas toward the lower
Mississippi Valley. Winds will begin the night from the S or SW
at or below 10 kt, veering to W`erly after midnight, then
finally to NW and N late as the leading edge of high pressure
tries to nose in from the north. Seas will average just 1-2 ft.

Tuesday through Saturday: Low pressure will track into and over the
area Tuesday into Tuesday night. Winds and seas will increase as
this occurs, and Small Craft Advisories will be possible for
portions of the waters Tuesday evening into Wednesday morning. The
low will lift away from the area on Wednesday, allowing conditions
to improve. High pressure will then return for the latter half of
the week. No additional marine concerns are anticipated.
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&&

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

&&

$$
NEAR TERM...
SHORT TERM...ETM
LONG TERM...ETM
AVIATION...
MARINE...