625
FXUS62 KCHS 301758
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
158 PM EDT Tue Apr 30 2024

.SYNOPSIS...
High pressure will prevail through much of the week. A weak
disturbance will move through today and Wednesday, then a weak
cold front will stall in the vicinity this weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
This Afternoon: Aloft, a mid-upper level ridge will be forced
further offshore as h5 shortwave energy progresses eastward
across the Southeast United States. At the sfc, a lee trough
will prevail well inland while the local area remains along the
western fringes of Atlantic high pressure. The pattern will
result in mainly dry conditions for most areas during the next
few hours, before h5 shortwave energy arrives late afternoon. A
southerly sfc wind will advect greater moisture across the
region (PWATs 1.25-1.50 inches) while ample sfc heating under
thin cirrus leads to afternoon highs in the low-mid 80s away
from the beaches. Instability remains modest mid afternoon, but
a few showers can not be ruled out near the vicinity of a
seabreeze circulation moving inland. By late afternoon, greater
precip chances arrive across far inland locations, where higher
moisture/instability aligns with h5 shortwave energy approaching
from the west. Convection should remain somewhat disorganized
given modest CAPE and bulk shear. However, a few stronger
thunderstorms can not be ruled out well inland when forcing and
moisture convergence becomes enhanced as the shortwave encounters
the local seabreeze by early evening. Gusty winds and small
hail will be the main concerns should a stronger thunderstorm
occur. The highest chances for convection should remain along
and west of I-95, where 30-45% PoPs remain in the forecast.

Tonight: The h5 shortwave passes through the forecast area, reaching
near the coast or offshore by Wednesday morning. The lee trough
remains in place, while the western side of the Atlantic ridge pulls
a bit further out to sea. There is just enough instability and ample
moisture for the shortwave to work with, so chance PoPs remain for
much of the night. Although with the passage of the shortwave,
probabilities drop off across Georgia late. The nocturnal environment
is not conducive for severe storms after the early evening.

There are indications of some fog forming across parts of Georgia
after midnight. But with perhaps too much lingering cloud cover, we
refrained from including in the forecast at this time. Given the
cloud cover, overnight lows should be more mild than previous
nights, generally in the lower 60s inland to mid-upper 60s closer to
the coast.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
A few showers could move through the Charleston Tri-County area
Wednesday morning in association with the tail end of the upper
shortwave. Weak upper level subsidence will develop during the
afternoon as shortwave ridging occurs. However, moderate
moisture will remain in place during the afternoon, and a decent
sea breeze will develop, potentially popping isolated showers.

Deep layered ridging Thursday into Friday should maintain dry
weather with above normal temperatures. A shortwave could
approach far western areas late Friday afternoon so it`s
possible some convection could drift into those zones late in
the day. Highs will reach the mid to upper 80s both days.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
A relatively zonal flow will develop Friday night and continue
into early next week, with occasional shortwaves rippling
through. A weak cold front is forecast to stall across far
inland areas over the weekend. Tropical moisture will spread
into the area with PWATs hovering around 1.7" much of the
period. Isolated to scattered mainly diurnal convection is
expected, along with above normal temperatures.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Tempo MVFR cigs are possible with a few showers near the CHS
terminal for the next hour (18-19Z) while a seabreeze makes away
inland. Otherwise, VFR conditions are expected at all airfields with
wind gusts up to 15-20 kt in wake of the seabreeze this afternoon.
Scattered showers and thunderstorms upstream could eventually impact
the terminals early evening. Probabilities remain too low to
include in the latest TAF issuance, but tempo MVFR cigs/vsbys
could eventually be needed. VFR conditions should then prevail
at all terminals by late evening and prevail through 18Z Wednesday.

Extended Aviation Outlook: VFR will generally prevail.

&&

.MARINE...
This Afternoon and Tonight: High pressure centered across the
western Atlantic will extend toward the Southeast Coast while a
trough remains inland. The pattern will favor a southerly sfc
wind around 15 kt or less across all local waters with the
exception of the Charleston Harbor this afternoon, where 20 kt
gusts are possible near a seabreeze circulation developing, then
shifting inland. Seas will range between 2-4 ft, largest across
offshore Georgia waters. Mariners should remain alert for
thunderstorms later today, but mainly this evening and/or
tonight, with a few potentially resulting in gusty winds and
frequent lightning strikes.

Wednesday through Sunday, no marine concerns expected. Atlantic
high pressure will remain the dominant feature with a relatively
weak gradient in the area. Wind speeds will generally stay below
10 kt except right along the coast in the afternoon sea breeze,
and seas will mostly run 2-3 ft.

&&

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

&&

$$

NEAR TERM...DPB
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...DPB
MARINE...DPB