166
FXUS62 KCHS 130556
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
156 AM EDT Mon May 13 2024

.SYNOPSIS...
High pressure will exit the coast early Monday with a storm
system approaching from the west. An active weather pattern
will start on Monday with multiple rounds of showers and
thunderstorms possible through Wednesday.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Aloft, a ridge axis extending from the Gulf Coast north through the
Ohio Valley will gradually nudge east late night, placing a fairly
strong jet axis across the Carolinas and western Atlantic. At the
sfc, high pressure will remain across the region, but will slowly
nudge east across the western Atlantic. The pattern will favor quiet
weather conditions through the night, although high clouds will be
in place and upstream convection across the Deep South along with
increasing isentropic lift could lead to mid-level clouds shortly
prior to daybreak, mainly across southeast Georgia. There should be
a band of high based radar returns nosing across southeast Georgia
late, but dry air depicted off the sfc in soundings indicates
measurable rainfall is not expected through daybreak. With high
clouds in place and additional clouds anticipated late, low temps
will remain more mild than recent nights. In general, low temps
should range in the upper 50s to lower 60s inland to upper 60s/near
70 at the beaches.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY/...
Mid level low initially over the Central Plains Monday morning
will shift eastward to the Mississippi Valley through Tuesday,
with a series of shortwaves expected to track over the local
region ahead of this feature. A surface low takes a similar
path, with a warm front lifting north into the region. Moisture
returns back to the area with PWats surging to over 1.75 inches,
which is well above seasonal climatology. This sets the stage
for a period of unsettled weather.

Monday will start dry then rain chances should increase from the
southwest through the day and into the evening. Consensus indicates
that instability during this time period will remain rather limited,
so while thunder will certainly be in play, the severe threat is
low. The highest shower/thunderstorm coverage and rain chances will
be during the latter half of Monday night and Tuesday when the
better forcing arrives. Still uncertainty in the convective
evolution and specific timing, but wind shear values will be
supportive of storm organization. Instability is in question
depending on how earlier convection works out, but current model
progs feature the highest CAPE values over southeast Georgia.
Regardless, all areas will need to be watched for stronger to severe
storms. Marginal Risk for severe weather from SPC Day 3 Outlook
persists. Area-wide rainfall totals throughout the event currently
average in the 2-3 inch range, with isolated higher amounts
possible. Pockets of heavier rainfall could result in ponding on
roadways and minor flooding especially in urban and poor drainage
areas.

The bulk of activity should transition offshore through Tuesday
night with decreasing rain chances in its wake.

The main upper wave and associated surface reflection will pass
across the mid-Atlantic states on Wednesday and eventually offshore.
With some upper support and lingering moisture, isolated to perhaps
scattered showers/thunderstorms will be possible. Outside of
convection, winds will become gusty with gusts to around 20-25 mph.
Temperatures should peak in the mid to upper 80s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Ridging briefly passes across the region on Thursday with no weather
concerns. More unsettled weather is expected to return late week
into the weekend as the next low pressure system tracks towards the
East Coast. Forecast details still need to be worked out, but
regardless, at least scattered showers and thunderstorms will be
possible both Friday and Saturday. Temperatures through the period
are forecast to be near to above normal.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
VFR conditions will persist at KCHS/KJZI/KSAV terminals through at
least early Monday afternoon, before cigs lower to MVFR with the
approach or rain/showers from the southwest late Monday afternoon
into the evening. Greatest chances for flight restrictions should
occur at the SAV terminal, where prevailing MVFR cigs begin at 22Z
Monday, followed by lower MVFR cigs and vsbys by around 01Z Tuesday.
MVFR cigs/rain should arrive at CHS/JZI terminals starting around
23Z Monday, then gradually lower through the evening. IFR conditions
are possible at the terminals Monday evening, but confidence remains
too low to include in the latest TAF issuance.

Extended Aviation Outlook: Flight restrictions are possible in low
clouds and showers/thunderstorms Monday afternoon into midweek as a
storm system impacts the region.

&&

.MARINE...
Tonight: Surface high pressure currently across the area will slowly
nudge offshore prior to daybreak, resulting in quiet marine
conditions for the rest of the night. In general, south-southwest
winds should range between 5-10 kt with seas between 1-2 ft.

Monday through Friday: No concerns over the marine area on Monday.
Winds will increase Monday night into Tuesday and will remain fairly
gusty into Wednesday as low pressure tracks towards the East coast.
Seas also build and while it looks fairly marginal at this time,
there is potential for a period of Small Craft Advisories over
portions of the waters, especially the outer Georgia and Charleston
county waters. Conditions improve for Thursday. Next weather system
is expected late week into the weekend with conditions currently
held below advisory criteria.

&&

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

&&

$$

NEAR TERM...DPB
SHORT TERM...ETM
LONG TERM...ETM
AVIATION...DPB/ETM
MARINE...DPB/ETM