000
FXUS62 KCHS 181951
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
351 PM EDT Thu Apr 18 2024

.SYNOPSIS...
High pressure will persist through tonight. A slow moving front
will bring unsettled weather to our area Friday through early
next week. High pressure returns by the middle of next week.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
This Afternoon and Tonight: Zonal flow will prevail aloft while
at the surface high pressure will hold strong. Dry conditions
are expected through this afternoon and overnight, with
temperatures reaching into the mid to upper 80s. A sea-breeze
circulation has developed along the direct coastline, tipping
winds to the S and limiting the high temperatures to the upper
70s along the beaches. Overnight will see little change in the
large scale flow, resulting in continued quiet, rain-free
conditions. Low temperatures are expected to only dip into the
low to mid 60s.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Weak high pressure over the western Atlantic will shift east on
Friday. Aloft, a weak shortwave will move off the coast in the
morning, then relatively zonal flow will persist for the rest of
the day into Friday night. The lowest 300 mb will feature 10-20
kt WNW flow through the afternoon. The resulting downslope
compression will push highs into the upper 80s to around 90.
This will also produce large scale subsidence, limiting the
potential for convection to develop. There will be a weak cold
front sagging toward our NW zones late in the afternoon. Despite
the subsidence, models show SBCAPE around 1500 J/kg and 30-40 kt
bulk shear, so we cannot rule out isolated to scattered showers
and tstms, mainly inland. And an isolated severe storm is not
out of the realm of possibility.

Saturday will remain quite toasty due to the broad upper ridge
and low-level compression along the southern edge of the
backdoor front. Highs will be in the upper 80s to lower 90s. A
bit more convective coverage is expected due to some late day
upper shortwave energy, the weak surface boundary in the
vicinity, and higher PWATs.

The upper level pattern changes drastically on Sunday as an
upper trough progresses across the eastern United States and the
surface front drops farther south. Temps will be considerably
cooler on Sunday due to overcast skies and cool advection. Highs
across inland SC could only be in the lower 70s, though farther
south along the Altamaha River in GA we expect low to mid 80s.
Numerous to widespread showers and thunderstorms are expected,
especially late in the day, due to strong synoptic scale
forcing and ample low-level moisture.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Wet weather continues Sunday night as the primary shortwave
swings through and a weak low moves up the coast. Some areas
could see upwards of half an inch of precipitation (locally
heavier). Rain should taper off by Monday morning as cool high
pressure builds in.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
VFR conditions will prevail at CHS/JZI/SAV terminals through 18Z
Friday.

Extended Aviation Outlook: A slow moving front could bring
occasional flight restrictions late Saturday through Monday.

&&

.MARINE...
Tonight: Quiet conditions are forecast across the marine waters
as high pressure remains the dominant feature across the region.
SW winds around 10 knots are forecast and seas averaging 2 to 3
ft.

A moderate S/SW flow Friday into Saturday will turn to the NE
late Saturday night as a cold front drops through the area.
Sunday through Monday will feature the strongest winds of the
period with readings occasionally ranging from 15-20 kt due to a
tightening gradient. Slightly weaker NE flow expected Tuesday,
then winds turn back to southerly by Wednesday as weak high
pressure builds over the western Atlantic.

&&

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

&&

$$

NEAR TERM...CPM
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...CPM/JRL
MARINE...CPM/JRL