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609
FXUS62 KCHS 251502
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1102 AM EDT Sat May 25 2024

.SYNOPSIS...
A weak disturbance will move through the area this evening. Hot
conditions expected for Sunday and Memorial Day. A cold front
could bring impacts to the region Monday night into Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
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Late morning satellite indicated that the forecast area was
mostly sunny. As a result, temperatures have warmed into the mid
to upper 80s across the region. However, based on satellite
trends, cirrus debris clouds will increase from the west,
sourced from a band of thunderstorms positioned over northern
GA/AL. The arrival of the clouds should slow the warming, likely
leading in temperatures to peak around 90 degrees by early this
afternoon.

Modifying the 12Z KCHS sounding, the environment across the
forecast area this afternoon should feature MLCAPE around 2000
J/kg or normalized CAPE of 0.15-0.2. DCAPE values may range
between 1000-1200 J/kg, especially across SE GA. The thermal
profile combined with effective bulk shear of 30-35 kts may
support strong to severe thunderstorms across SE GA/SC this
afternoon and evening. The first round of severe weather could
be associated with the arrival of the MCS over northern GA.
Recent runs of the HRRR indicate that the leading cells may
arrive over SE GA around 3 PM. SPC has issued a mesoscale
discussion for this activity, indicating a 40 percent chance for
a Watch. At the same time, sea breeze showers and thunderstorms
should initiate over portions of Charleston and Berkeley
Counties. Some of these storms may pulse and become quite tall,
yielding some potential for damaging wind gusts.

By late this afternoon, the two modes of convection, MCS
related over SE GA and sea breeze for the coastal counties, will
produce numerous outflow boundaries with the moderate DCAPE.
These boundaries will largely determine the overall timing,
placement, and duration of convection heading into the early
evening. The environment will feature deep moisture, PW values
between 1.5-1.7 inches. HREF indicates that some thunderstorm
clusters will have the potential of producing 1.5-2 inches in a
3-hr period this afternoon and evening.

Overnight: A mostly dry night will prevail once evening convection
dies off and the mid-level impulses propagates offshore. It
will remain warm and fairly humid with lows ranging from the
upper 60s well inland to the mid 70s at the beaches. There is a
chance that little fog could develop early Sunday morning,
especially where rain falls today. However, the fog could remain
fairly light with no significant impacts.
-- End Changed Discussion --

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
Ridging builds overhead on Sunday which will aid in limiting
convection. Rain chances are no higher than 20%. Main story
will be the unseasonably hot temperatures. Highs peak in the low
to mid 90s across most locations. Lows Sunday night only fall
to the low/mid 70s.

Mid level ridge axis shifts offshore on Monday/Memorial Day as a
broad trough moves into the eastern U.S. At the surface, a cold
front will approach the region from the west. Little convection is
expected through at least mid-afternoon then upstream showers and
thunderstorms could move into the area later in the day into the
evening. There is potential that this activity is more
organized and pose a risk for stronger storms with gusty winds.
Highest rain chances shift offshore late Monday night/early
Tuesday morning. Lows will mainly be in the upper 60s to lower
70s.

The front should push offshore on Tuesday. Deepest moisture also
exits the area, and the weather looks fairly quiet with just
isolated showers/thunderstorms are still possible. High
temperatures again above seasonal normals in the lower 90s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
High pressure builds into the region for late week behind a
secondary cold front that passes through later Wednesday night
or early Thursday. Rain-free forecast in tact, essentially
disregarding the outlier/wetter GFS. Temperatures should return
back to more seasonable levels.

&&

.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
25/12z TAF Discussion:
KCHS/KJZI/KSAV: VFR will prevail. Isolated showers/tstms could
develop along the sea breeze by mid-afternoon and get close both
KCHS and KJZI. Another cluster of showers/tstms will move
southeast out of the Midlands later this evening and make a run
for KCHS and KJZI as well. VCTS was highlighted roughly 20z-04z
to account for this. For KSAV, still watching for a possible
convective cluster to move out of central Georgia later this
afternoon and make a run for the Georgia coast. Latest H3R and
RAP still are not in great agreement on placement and timing of
this convection. Confidence is still not high enough at this
juncture to include any mention of TSRA. This will once again be
reevaluated for the 18z TAF cycle.There could be a little ground
fog that develops prior to daybreak, but this is not expected to
be significant at any of the terminals. Isolated to perhaps
scattered showers/tstms will develop over the area this
afternoon/evening. Confidence in the timing/placement of
convection remains fairly low this far out with the lack of any
meaningful forcing mechanism. There could be slightly higher
chance at impacts at KCHS/KJZI during the mid-afternoon as
isolated convection pops near the sea breeze, then KSAV late
afternoon/early this evening as there are signals that a more
concentrated area of showers/tstms could make a run for that
terminal as it moves out of central Georgia. Given the low
confidence on these scenarios, no mention of TSRA will be
included for the 06z TAF cycle. The need for TSRA will be
reevaluated for the 12z TAF cycle.

Extended Aviation Outlook: Brief flight restrictions are
possible due to showers/thunderstorms each afternoon/evening.

&&

.MARINE...
Through Tonight: A southerly flow regime will prevail through
tonight. Winds will remain less than 15 kt with seas 1-2 ft. A
cluster of tstms could move off the Georgia coast later this
evening which could produce convective winds >34 kt.

Sunday through Thursday: South to southwest winds persist through
early next week. A cold front will then pass through the waters
before high pressure builds for late week. Conditions stay below
Small Craft Advisory through the period. Winds speeds average 15
knots or less with seas 2-3 feet on average.

&&

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

&&

$$

NEAR TERM...NED
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...