950
FXUS62 KCHS 092357
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
757 PM EDT Thu May 9 2024

.SYNOPSIS...
A cold front will approach the area tonight, then move offshore
Friday. High pressure will prevail for the weekend into early
next week. A storm system could affect the area by the middle
of next week.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Deep convection has pulled offshore and continues to move away.
This will be followed by a period of at least partial clearing
in advance of what is expected to be an MCS closer to daybreak
or shortly thereafter that arrives from the west.

In between, and dependent upon how much clearing occurs, we do
anticipate stratus developing, along with some fog. Geostrophic
winds look a little too much for any significant fog, but maybe
something down in the 2-3 mile range since the grounds are so
wet. We will re-evaluate this again with subsequent updates.

Temperatures really won`t move much through the night, with
actual lows in the mid 60s to lower 70s.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
The forecast for Friday is quite tricky. A quasi-zonal flow will
persist aloft, though we will see several potent shortwaves
ripple through the area during the day. Given the high theta-e
airmass across the Southeast, ample instability should be in
place to support convective development with these upper vort
maxima. Furthermore, the presence of 50-60 kt of 0-6 km bulk
shear will favor organization of the convection once it become
established. Most of the guidance continues to indicate the most
impressive shortwave will move through southeast SC/GA between
15Z and 18Z.

There is surprising agreement between the synoptic models and
the CAMs that a large area of showers and thunderstorms will
move across the forecast area between 9am and 3pm Friday. It
appears that an MCS could be ongoing across south central GA at
daybreak that then pushes east through our area. Thus, the
greatest coverage of convection would occur over our southeast
GA zones. This is also where the strongest convective indices
are expected, so our primary focus for severe weather potential
is in southeast GA and extreme southern SC. Damaging winds
appear to be the primary threat assuming the convection becomes
organized into a line. Isolated large hail or tornadoes can
never be completely ruled out. Farther to the north in SC, at
least scattered showers and thunderstorms will move through, but
extensive cloud cover in the morning and less available
instability should reduce the overall severe weather potential.
Rainfall totals on Friday will range from 1-1.5" in southeast GA
and 0.5-1.0" in southeast SC.

The brunt of the convection is expected to be off the coast by
3pm. A secondary shortwave will drop into SC early Friday
evening, pushing the cold front into the area. A big question
mark is what convection, if any, develops out ahead of the
front. It will heavily depend on what happens in southern SC
with the first batch of convection and whether or not the
airmass gets worked-over as a result. If convective coverage is
limited during the early afternoon activity, a greater degree of
destabilization could occur in southern SC, allowing for a more
conducive airmass for convective development late Friday
afternoon or early evening. For now we penciled in scattered
PoPs across eastern Berkeley/Charleston Counties late afternoon
and early evening.

Saturday will be dry and noticeably cooler with highs in the
upper 70s. Sunday will warm up a bit due to upper ridging, with
highs in the mid 80s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Early next week will briefly start off quiet before a warm front
extending across the Deep South lifts north. Conditions look quite
unsettled beginning late Monday night into Wednesday due to
plentiful upper forcing and deep moisture building in. Several
rounds of showers and thunderstorms are expected.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
KCHS/KJZI/KSAV: Convection is over with, and VFR has returned
to all sites. With at least some clearing and due to the wet
grounds, some stratus and fog will develop overnight into Friday
morning. Flight restrictions are likely for several hours, at
least down into the MVFR category, but potential for even IFR.

An MCS will move in from the west Friday morning, impacting
especially KSAV into the early or mid afternoon. For now we show
just -SHRA (also VCTS at KSAV), and additional flight
restrictions are possible. If there is an MCS that impacts the
terminals, strong winds and heavier rains could occur.

Extended Aviation Outlook: VFR conditions will return for the
weekend into early next week. Scattered convection expected
Monday night and Tuesday.

&&
Tonight: Expect winds to be mainly S-SW 10-20 kt. A few gusts
up to 25 kt are possible at times, but not enough to justify
a Small Craft Advisory. Seas will be in the 2-4 ft range. Low
stratus and maybe some fog will develop overnight, and we`ll
monitor to see if any advisory or at least a statement will be
warranted.

Friday: A decent SW gradient expected in advance of a cold
front, though winds will be quite variable once convection moves
offshore midday. Late in the afternoon and early evening, wind
gusts could approach 25 kt, so it`s not out of the realm of
possibility that a short-duration Small Craft Advisory is
needed. Due to the low confidence we will hold off on any
issuance with this package.

Marine conditions will improve Saturday morning as high pressure
builds in from the west. Winds/seas expected to increase Monday
night into Tuesday ahead of the next storm system.

&&

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

&&

$$

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