729
FXUS62 KCHS 100215
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1015 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/...
Now that the higher level clouds have pulled out from earlier
convection, with the wet grounds we are seeing patchy low
stratus form. Some guidance indicates that there could be fog
developing as well. But we`re still anticipating no worse than
about 2-3 miles, since geostrophic winds are just too much. So
no mention in the actual forecast.

Our attention turns to the west, where an MCS in Alabama and
Georgia will approach overnight. But it is expected to weaken as
it does so, as there are poor lapse rates, limited MUCAPE and
0-1 km bulk shear, and likely too much CINH. We do show some
slight chance of showers in our Georgia zones close to daybreak
however.

An additional MCS in Mississippi and Louisiana, and maybe even
a third from Texas would not get here until Friday.

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 /02Z FRIDAY THROUGH TUESDAY/...
KCHS/KJZI/KSAV: VFR has returned to all sites. With at least
some clearing and due to the wet grounds, some stratus and fog
will develop 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.

&&

.MARINE...
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. Likely not
enough fore an advisory, but possibly a Marine Weather Statement
for Charleston Harbor.

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...