540
FXUS62 KCHS 160005
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
805 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/...
KCHS/KJZI: Scattered SHRA/TSRA could impact both terminals this
evening. For now we prefer to show VCTS (with a tempo for -SHRA
at KCHS) through 02-0230Z and will amend if necessary. Both
sites will also experience a wind shift to the NW at 20-25 kt in
advance of any convection.

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: 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 will 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...None.

&&

$$

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