527
FXUS62 KCHS 121715
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
115 PM EDT Mon Aug 12 2024

.SYNOPSIS...
A stationary front will remain just to the west through Tuesday
before dissipating. Weak high pressure will build in from the
north during the middle of the week and prevail into the latter
part of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Early this afternoon: No change to the forecast thinking.
Previous discussion continues below.

Late this morning: Surface analysis continues to reveal a weak
front situated to the west and north of the forecast area. We
start the day with mostly clear skies and plenty of sun, which
is allowing temperatures to rise into the upper 80s already.
Concerning convection chances this afternoon, it appears the
best instability will reside across our southeast South Carolina
counties and down along the Georgia coast. Guidance suggests
that some lower dew points will filter in across interior
southeast Georgia which will lower the thunderstorm risk there.
Hi-res models continue to highlight Colleton County through the
Tri-County region, inland of the coast. This area will be
situated near the aforementioned front as well as the afternoon
sea breeze. With DCAPE values progged to be around 1,000 J/kg,
a severe threat will exist for damaging wind gusts. However, no
organized severe weather is expected as the stronger storms will
likely occur where more significant boundary interactions
occur.

With highs in the low to mid 90s and dew points in the mid
to upper 70s along the Georgia coast up through Beaufort and
Jasper counties, heat index values are still forecast to reach
108-110 degrees. Therefore, the Heat Advisory remains in effect.
We could see isolated locations get up to near 108 in the Tri-
County region, but the Heat Advisory risk is much more marginal
there.

Tonight: Convection will diminish through the evening hours
with quiet conditions overnight. Lows will dip back into the
upper 70s to around 80.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
Tuesday: A weak surface front and area of low pressure across
the Midlands will meander across the area through the day. A
trough across the Northeast and Mid-Atlantic states will dig
into the Southeast late which will push those surface features
southward. Low-level convergence near the front, in addition to
the sea breeze, will be enough to support at least scattered
showers and thunderstorms during the afternoon and evening.
Guidance favors southeast South Carolina for the greatest
coverage with conflicting coverage across southeast Georgia. The
forecast reflects at least slight chance POPs across our
southern zones considering PWATs in that area will be around 1.7
inches. With plenty of instability, we can`t rule out a
stronger storm or two, especially where boundary interactions
occur. However, the overall severe threat will be low. Also,
some storms could produce locally heavy rainfall. Given that
ground conditions are wet and some areas are still experiencing
flooding, there is little to no tolerance for additional
rainfall. Therefore, any thunderstorm that develops will have
the potential to quickly produce flooding issues. High
temperatures are forecast to reach the low to mid 90s and
overnight lows will be in the low to mid 70s away from the
coast.

Wednesday: A trough across the Northeast and Mid-Atlantic
states will continue to dig into the Southeast, helping to nudge
the aforementioned weak front offshore. Models suggest a very
narrow swath of deep moisture passing over the area associated
with the front, in addition to upper forcing, which will again
bring at least scattered convection during the afternoon/evening
hours. Wednesday will be touch cooler with highs in the upper
80s across our southeast South Carolina counties and low 90s for
our southeast Georgia counties. Min temps will largely bottom
out in the low to mid 70s with some inland spots in the upper
60s.

Thursday: Weak high pressure will begin to build in from the
north, along with relatively drier and cooler conditions. This
will keep rain chances to a minimum. The current forecast
features slight chance to chance POPs, which may even be
overdone.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
Weak high pressure will linger for a day or two before a cold
front quickly approaches. This will result in lesser chances of
diurnal convection during the weekend. The front could pass over
the forecast area early next week, which could lead to higher
rain chances. Temperatures should rise a degree or so each day
with highs back into the low 90s this weekend, around near-
normal for this time of year.

&&

.AVIATION /17Z MONDAY THROUGH FRIDAY/...
Isolated to scattered thunderstorms are possible this afternoon
and evening, with the best coverage expected to be around KCHS
where we have included VCTS from 1930-21z. Can`t rule out a
thunderstorm near KSAV or KJZI, but will handle those with
amendments as necessary. Overnight, there could be some shallow
ground fog around, but no reduced visibility expected at the TAF
sites.

Extended Aviation Outlook: Brief flight restrictions are
possible in afternoon and evening showers/thunderstorms through
the period.

&&

.MARINE...
Today: Southwest winds continue across the coastal waters today
with winds trending a bit more southerly this afternoon with
the sea breeze. Sustained winds of 10 to 15 kts with some higher
gusts. Seas should generally range between 2 to 3 ft in a mix
of southeasterly medium period swell and southerly wind chop.

Tuesday through Saturday: A deep offshore ridge will result in
southwest flow around 10 kt or less Tuesday. Wednesday
afternoon, high pressure will begin gradually build in from the
north after a weak front departs southward which will cause
winds to shift out of the northeast. Seas will average 2-3 feet;
however, by the end of the week seas will start to rise as
increasing swell arrives from what could be a strengthening
tropical system over the open Atlantic. Small Craft Advisories
could be needed for a portion of the marine zones for 6 ft seas.

&&

.HYDROLOGY...
Most of southeast Georgia and southeast South Carolina remains
quite vulnerable to additional rainfall following the 10-20
inches of rain that fell last week. Many areas are still
experiencing ongoing flooding, and any additional rainfall from
thunderstorms will certainly not help conditions improve.
Scattered to numerous thunderstorms are forecast each afternoon
and evening through midweek, and any locally heavy rainfall
could produce new areas of flooding.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory until 6 PM EDT this evening for GAZ116>119-
     137>141.
SC...Heat Advisory until 6 PM EDT this evening for SCZ047>049-051.
MARINE...None.

&&

$$

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