715
FXUS62 KCHS 140613
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
213 AM EDT Tue May 14 2024

.SYNOPSIS...
A warm front will lift northward through the area Tuesday
morning, followed by a cold front from the west Tuesday night.
High pressure will return to the area by Thursday, followed by
another storm system this weekend.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A complex of thunderstorms will continue to move through the Deep
South and northwest Gulf of Mexico late tonight, eventually
traversing across southern Georgia and northern Florida around
daybreak. The relatively quiet conditions early tonight will give
way to increasing convective chances late, mainly starting a few
hours prior to daybreak while isentropic ascent persists and various
mid-level impulses traverse aloft as a sfc warm front lifts north
into southern areas. Isolated to scattered showers remain possible
across the area for the next few hours, but with increasing
instability to the south of the northward advancing warm front, the
risk for thunderstorms will climb approaching daybreak. Any small
severe potential will likely remain after 6 AM, but a few stronger
thunderstorms are not out of the question due to the proximity of
the warm front. Overnight lows will not change much through the
night, and could even increase in wake of the warm front prior to
daybreak.

There are some indications of a weak wave of low pressure forming
near the coast of Georgia or lower South Carolina near dawn and
should this occur, could enhance the risk for both thunderstorms and
the intensity of the rain, mainly along the coastal corridor.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/...
Tuesday and Tuesday night: The most active portion of the short
term period will come Tuesday and Tuesday night with a rather
complex forecast. As Tuesday morning begins, a warm front will
be lifting northward across the forecast area which should then
clear to the north by late morning. Forcing aloft will be
provided by a closed low and associated trough near the
Mississippi Valley that will gradually work eastward through the
day. At the start of the day, the main convective complex will
likely be crossing north Florida, with other convection ongoing
along and near the warm front. While the activity across north
Florida should stay south of the Altamaha, it could sneak into
far southern southeast Georgia along the coast and bring the
potential for strong to severe thunderstorms. Along the warm
front, thunderstorms should be ongoing and lifting to the north
and northeast through the morning. We have the highest rain
chances during this morning time period, with 60-80 percent
along the southeast South Carolina coast and along the Savannah
River and to the northeast. As the warm front gets north of the
Santee River and the activity to the south pushes out over the
coastal waters, we should see a lull before additional
convection tries to develop later in the afternoon after
recovery ahead of the cold front from the west. This activity
will likely extend well into the evening before the frontal zone
pushes off the coast late. Activity during this time should be
more scattered in coverage, and rain chances are held more into
the 30-40 percent range as a result.

Severe Thunderstorms: With the morning activity, the severe threat
will likely be tied to the environment along and near the warm
front. Model soundings do show MLCAPE around 1,000 J/kg, with 40-50
knots of mid-level flow. There is also some decent veering thanks to
the presence of the warm front that could yield SRH values on the
order of 150-200 m2/s2. So while damaging wind gusts are the primary
threat, the ambient wind profiles will also produce a low end
tornado threat. The threat should wane by midday as the activity
moves off to the northeast with the front. Attention then turns to
the afternoon and evening. While the veering noted in the morning
diminishes, mid-level flow remains notable in the 40-50 knot range.
Also, mid-levels dry out and yield DCAPE values of 1,000 J/kg or
more which should help to enhance the damaging wind gust threat.
This potential with scattered thunderstorms will continue into the
late evening hours.

Rainfall: Total rainfall amounts are still generally expected to be
in the 0.50-1.50" range. The highest amounts are expected along the
southeast South Carolina coast up through the Charleston Tri-County
region. Rainfall amounts, especially at the high end of the range,
will be very dependent on exactly where thunderstorms track.

Wednesday through Thursday: The area will be situated within the
circulation around an area of low pressure near the Outer Banks.
While a few showers could linger across the Tri-County region early
on Wednesday, the bulk of the day is expected to be dry. Weak high
pressure will build in on Thursday and bring a quiet weather day.
Highs each day are forecast to reach the upper 80s for most
areas.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Shortwave ridging will pass through Thursday night ahead of a
shortwave that will cross into the Appalachians and the East Coast
through Saturday. A cold front is expected to approach Friday and
Friday night and push through the area on Saturday. An area of
thunderstorms is depicted by the model consensus and should impact
the area at some point during this time period. Active weather could
extend into Sunday as well, but there is uncertainty as to the
timing of the front and any thunderstorms associated with it. So the
overall theme of the long term period is increased rain chances and
above normal temperatures.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
A complex of showers/thunderstorms will shift just south of the local
area early morning while a warm front lifts north across the area
shortly after daybreak. The front will be the main contributor or
reduced cigs/vsbys, with at least scattered showers at times late
tonight into mid/late morning Tuesday. A thunderstorm can not be
ruled out at any terminal Tuesday morning with the warm front, but
probabilities are much too low at this stage to mention in the TAFs.

MVFR ceilings are expected to develop between 06-08Z at KSAV, and
should be delayed until 10Z at KCHS and KJZI. However, IFR is
possible at times, and adjustments could be made later on along/near
the warm front lifting north. VFR conditions should arrive to all
terminals Tuesday afternoon, starting at the SAV around 19Z, then at
CHS/JZI around 21Z, and should persist through 06Z Wednesday.
However tempo flight restrictions could eventually be needed at any
terminal for afternoon thunderstorms should probabilities
increase.

Extended Aviation Outlook: Additional showers and thunderstorms
could impact the terminals with brief flight restrictions
Tuesday evening. Otherwise, VFR conditions should prevail.

&&

.MARINE...
Tonight: South-southeast winds will remain elevated across local
waters overnight as a warm front lifts north late. Small Craft
Advisories will continue across Georgia waters through daybreak with
winds gusting around 25 kt at times. Seas will also remain elevated
as low pressure attempts to take shape just south of local waters.
In general, seas should peak near 6-7 ft across offshore Georgia
waters although some 8 ft waves are possible during the next hour or
two. Seas should range between 4-6 ft across nearshore Georgia
waters although 7 ft waves could drift into waters beyond 10 nm from
the coast. Further north, seas should range between 3-5 ft across
nearshore South Carolina waters, but will show signs of approaching
6 ft around daybreak as a warm front lifts north.

Tuesday through Saturday: A warm front will lift through the
waters early Tuesday and turn the flow from southeasterly to be
more southerly. Winds should mostly peak in the 15-20 knot
range, but there could be a few gusts to 25 knots at times.
Winds will diminish a bit later Tuesday, but then become
southwesterly and pick up ahead of a cold front that will push
offshore late Tuesday night. Winds should mostly be in the 15-20
knot range during this time. Winds will become more westerly
Wednesday night into Thursday, then southerly by Friday. Seas
will be highest Tuesday and Tuesday night, with 3-5 ft common,
and up to 6 ft expected in the outer Georgia waters and the
Charleston County waters. The advisory for the outer Georgia
waters goes through noon Tuesday and the Charleston County
waters goes into Tuesday evening.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory from 8 AM this morning to 8 PM EDT this
     evening for AMZ350.
     Small Craft Advisory until 6 AM EDT early this morning for
     AMZ354.
     Small Craft Advisory until noon EDT today for AMZ374.

&&

$$

NEAR TERM...DPB
SHORT TERM...DPB
LONG TERM...BSH
AVIATION...DPB
MARINE...DPB