-- Discussion containing changed information from previous version are highlighted. --
722
FXUS62 KCHS 152329
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
729 PM EDT Wed May 15 2024

.SYNOPSIS...
A cold front will move through late today, followed by high
pressure into Friday. A storm system will affect the area this
weekend, followed by high pressure from the north next week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Convection is starting to slip into our northwest tier early
this evening, within an environment that has a MLCAPE near 1000
J/kg, Normalized CAPE around 0.15 units, and 0-6 km Shear near
40 kt. Given DCAPE around 800 J/kg and SCP of at least 2 units,
there is still the risk for isolated strong or severe storms
until 9 or 10 pm. Should any occur, it would be where the sea
breeze boundary interacts with the incoming convection. This
would be for mainly the Charleston quad-county district.

For the early evening update we did adjust the PoPs to account
for recent trends, and we now have coverage as much as 40-50%
from Allendale and Hampton County through the Charleston quad-
counties.

Late this afternoon through tonight: The main forecast
challenge revolves around developing convection and its eastward
track through the evening hours. The near storm environment is
certainly supportive of a severe threat with MLCAPE around 2,000
J/kg, DCAPE of 1,000-1,200 J/kg, and effective shear around 40
kt. The main threat will be damaging wind gusts, but large hail
will also be a possibility. We still expect that convective
coverage will be isolated to scattered, and that the best threat
area is still north of the Santee River where a Severe
Thunderstorm Watch is in effect. Even being just outside the
watch, a couple of severe storms will be possible until the
activity shifts offshore later this evening. We should be
completely done by around 10-11 pm and the rest of the overnight
will be dry as the front passes offshore. Overnight lows are
forecast to fall into the mid 60s inland (with a few low 60s
possible), and upper 60s along the coast.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
A relatively progressive pattern will exist during the short
term period. A shortwave ridge will move through on Thursday,
yielding warm temps and dry weather. Highs expected to be in the
mid to upper 80s.

A deepening southerly flow will bring an increase in moisture
on Friday. A shortwave trough will lift northeast through the
area late Friday, potentially bringing a few showers or tstms in
from the west Friday afternoon.

A longwave upper trough will shift into the eastern United
States Friday night and Saturday. A tropical airmass will
overspread the area with PWATs approaching 2". A weak warm front
will lift north through the area Friday night, then a potent
shortwave will move through on Saturday. Fairly widespread
showers and thunderstorms are expected during this period with
many areas potentially receiving more than 1" of precipitation.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
The upper trough axis will swing through on Sunday, potentially
producing a few showers or tstms. Then, dry and warm weather
expected as an upper ridge gradually builds from the west.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
KCHS/KJZI: Scattered SHRA/TSRA could impact both terminals this
evening. For now we prefer to show VCTS through 02-0230Z and
will amend if necessary. Earlier there were hints of low stratus
maybe occurring late tonight and early Thursday. But no such
indications as of this time. So otherwise, VFR is expected
through 00Z Friday.

KSAV: VFR will prevail.

Extended Aviation Outlook: Showers and thunderstorms could
bring flight restrictions to all terminals Saturday and Saturday
night as a low pressure system impacts the region.

.MARINE...
This evening and tonight: Current observations show that winds
along the land/sea interface are quite gusty, especially along
the Charleston County coast. Weatherflow observations at Shutes
Folly and Fort Sumter in Charleston Harbor indicate that
frequent gusts of 25-30 knots are occurring, and we are issuing
a Small Craft Advisory through 8 pm. Otherwise, southwest winds
will remain elevated into the evening, with 15-20 knots quite
common. Through the late night, winds will turn more westerly as
a front passes offshore, and speeds will mostly top out around
15 knots. Seas should mostly be in the 2- 4 ft range, though up
to 5 ft in the outer Georgia waters and the Charleston County
waters. Also, isolated thunderstorms could pass through
Charleston Habor and the Charleston County waters through the
late evening. It isn`t out of the question that these storms
could produce gusty winds and some hail.

Thursday through Monday: Conditions through the period are
expected to remain below Small Craft Advisory criteria. High
pressure will build in at the surface on Thursday, then a cold
front pushes through on Saturday. High pressure returns early
next week.
-- End Changed Discussion --

&&

.MARINE...
This evening and tonight: Current observations show that winds
along the land/sea interface are quite gusty, especially along
the Charleston County coast. Weatherflow observations at Shutes
Folly and Fort Sumter in Charleston Harbor indicate that
frequent gusts of 25-30 knots are occurring, and we are issuing
a Small Craft Advisory through 8 pm. Otherwise, southwest winds
will remain elevated into the evening, with 15-20 knots quite
common. Through the late night, winds will turn more westerly as
a front passes offshore, and speeds will mostly top out around
15 knots. Seas should mostly be in the 2- 4 ft range, though up
to 5 ft in the outer Georgia waters and the Charleston County
waters. Also, isolated thunderstorms could pass through
Charleston Habor and the Charleston County waters through the
late evening. It isn`t out of the question that these storms
could produce gusty winds and some hail.

Thursday through Monday: Conditions through the period are
expected to remain below Small Craft Advisory criteria. High
pressure will build in at the surface on Thursday, then a cold
front pushes through on Saturday. High pressure returns early
next week.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for AMZ330.

&&

$$

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