853
FXUS62 KCHS 272348
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
748 PM EDT Mon May 27 2024

.SYNOPSIS...
A cold front will move into the region tonight, then stall
nearby through the middle of the week. High pressure will
return for the second half of this week.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Early this evening: Radar imagery really tells the story right
now. Virtually no convection is ongoing across the forecast area
and any upstream convection is still really far away. The entire
forecast area remains within a Severe Thunderstorm watch, but
overall, the potential for severe weather isn`t looking
particularly good. Clusters of severe thunderstorms developed
across central Georgia a few hours ago, but these so far have
had a distant southward drift and are on a clear trajectory to
miss the forecast area to the south. Also, this convection has
thrown out considerable debris cloudiness that has overspread
the region, limiting destabilization with the last few hours of
available diurnal heating. The environment continues to have
high DCAPE values (>1,000 J/kg) and sufficient instability, but
we need to see develop upstream and track in. As of now, that is
looking increasingly unlikely. We will continue to monitor for
the next couple of hours but current thinking is that the severe
threat is quickly dwindling.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Tuesday: The mid-levels will consist of a longwave trough over
the eastern half of the U.S. At the surface, a cold front will
be located along our coast early in the morning. It`s forecasted
to transition into a stationary front shortly thereafter and
meander along our coast through the early evening. By late
evening, it`ll transition back into a cold front and move
further offshore, and away from our area. Broad High pressure
will be centered over the Northern Plains overnight, with its
periphery building into our region. The highest moisture values
will remain just offshore, on the other side of the front. With
less moisture in place, there won`t be much instability in place
across our area, despite temperatures peaking in the lower 90s
away from the beaches. The synoptic models and long-range CAMs
hint at maybe an isolated shower or thunderstorm, mainly near
are coastal SC counties in the afternoon. Further south, more
dry air and capping should limit any convection from developing.
Anything that does manage to develop over our SC counties
should be weak, dissipating by sunset. The evening and overnight
will be dry everywhere. Lows will range from the lower 60s far
inland to around 70 degrees at the beaches.

Wednesday and Thursday: The mid-levels will consist of a
longwave trough over the eastern half of the U.S. Wednesday. The
trough will become more amplified along the East Coast
Wednesday night into Thursday, in response to ridging
approaching from the west. At the surface, broad High pressure
centered over the Northern MS Valley Wednesday morning will
shift to the Great Lakes region by late Thursday. The periphery
of this High will reach all the way into the Southeast U.S. both
days, bringing dry conditions. Afternoon dew points may fall
into the 50s away from the beaches, which will make it feel very
comfortable. Temperatures on Wednesday should peak around 90
degrees, and the lower to mid 80s on Thursday. No convection is
expected either day, but fair weather cumulus is expected both
afternoons. Lows Wednesday night will range from the lower 60s
far inland to around 70 degrees at the beaches.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A trough over the East Coast Thursday night will shift offshore
by later Friday, followed by a ridge building on Saturday, and
possibly prevailing into Monday. High pressure will be the
dominant surface feature during the long term. POPs will be
around 20% each afternoon with temperatures a few degrees below
normal.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
The main forecast challenge for the next few hours is the
potential for thunderstorms late this evening and into the early
morning hours. Overall, the threat looks considerably less than
it did with the 18z TAF`s, so we have made some considerable
changes. We have removed any thunder mention at KCHS and KJZI
and keep a VFR forecast there through the end of the 00z TAF
period. KSAV is going to be more difficult. As of now, it
appears that most (if not all) of the ongoing upstream
convection will pass to the south and miss the terminal.
Therefore, we have removed removed the TEMPO group for thunder,
and have opted for a period of showers from 03-06z. We will
handle any short term adjustments with amendments.

Otherwise, the rest of the TAF period looks quiet. There could
be an isolated thunderstorm near KCHS and KJZI Tuesday
afternoon, but chances are too low to include at this point.

Extended Aviation Outlook: VFR.

&&

.MARINE...
Sea breeze influences will help in the enhancement of winds
into this evening, with S and SW winds as high as 15 or 20 kt
and gusty. There will be a few gusts near 25 kt at times in
Charleston Harbor and near the coast of Charleston County. But
not enough to warrant a Small Craft Advisories. Winds will veer
more SW or WSW at less than 15 through the night, altered
temporarily by convection that moves through during the mid or
late evening into the early post-midnight hours as an upstream
cold front draws closer. Outside of convection, seas will
average 2 to 3 feet.

That convection will generate a risk to mariners of severe
t-storms capable of producing gust in excess of 35 or 40 kt,
hail, cloud to water lightning strikes, and reduced visibilities
in heavy rains. There is also a non-zero risk for a waterspout.
Special Marine Warnings will likely be required for some of
these storms.

Extended Marine: Rather tranquil conditions are expected. A
cold front will be located along our coast early Tuesday
morning, moving further offshore, and away from our area Tuesday
night. High pressure will then gradually move towards our area
midweek and prevail through the weekend. Even the sea/land
breezes don`t appear to be too strong during this time period.
Wind speeds should average 15 kts or less. Seas will be 4 ft or
less.

&&

.CLIMATE...
Record High Minimum Temperatures:

May 27:
KCHS: 76/1991
KCXM: 79/2019
KSAV: 77/1878

&&

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

&&

$$

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