034
FXUS62 KCHS 271700
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
100 PM EDT Thu Jun 27 2024

.SYNOPSIS...
High pressure will remain over the western Atlantic while weak
fronts linger near the area through the end of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
A trough axis will push through the New England through the day
today, while along the southern periphery an associated
shortwave trough will swing through the southeastern states.
According to 12Z upper air analysis, this shortwave is
positively tilted and rather elongated, extending from the
southern Mid-Atlantic into the Florida Panhandle. Ongoing
convection across southwestern GA and the Florida Panhandle can
be attributed to this shortwave feature. As the feature
progresses eastward, convection is forecast to begin
overspreading the local forecast area. Some weak returns are
already being picked up by KCLX as of 1630Z across Tattnall and
Long counties in southeast GA. CAMs have really struggled today
to resolve the ongoing convection, with most models depicting
the ongoing convection over GA dissipating before it reaches the
local forecast area. All signs point to this convection holding
together and reaching the local forecast area by 3 PM. SPC
mesoanalysis depicts a region of higher ML CAPE values (roughly
2000 J/kg) as well as DCAPE values around 1000 J/kg across far
southeast GA. A strong to marginally severe thunderstorm is
certainly possible this afternoon. PoPs have been adjusted to a
slightly earlier arrival time across southeast GA to account for
the ongoing convection to the south. After convection moves into
southeast GA further convective initiation is likely across the
remainder of the forecast area, and numerous showers and
thunderstorms remain mentioned in the forecast.

Another forecast challenge for the day is the high temperatures.
A Heat Advisory remains in effect for several counties across
the SC Lowcountry. However, thicker than anticipated cloud cover
has limited high temperatures. The high temperatures have been
bumped down a degree or two with the latest forecast update.
Conditions are still hot and humid out, with dew points along
the coastal corridor reaching into the upper 70s. The Heat
Advisory will be in effect until 6 PM this evening. With any
breaks in cloud cover temperatures should be able to quickly pop
up a few degrees.

Tonight: Upper level troughiness lingers through the night and
it`s unclear if the surface boundary actually pushes through or
simply stalls/washes out across the region. As mentioned above,
convection is looking to linger through the evening hours,
moving off the coast and diminishing late evening and overnight.
Overnight lows should dip into the middle 70s most areas
(73-78F), warmer along the coast of course, with some fog
possible particularly in areas that do receive decent rainfall.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
Friday: The mid-levels should consist of a shortwave hovering over
our region in the morning. It is expected to dissipate into the
afternoon. Weak High pressure is forecasted to form over the
Southeast during the evening and overnight. At the surface, a
stationary front should be spread across our far inland counties in
the morning. It`s expected quickly lift north as a warm front into
the afternoon, becoming located well north of our area by the
evening hours and overnight hours. Deep moisture will persist across
the region. PWATs should stay ~2.25", which is above the 90% mark
for CHS per SPC Sounding Climatology. The heat won`t be as intense,
with highs expected to reach the lower to mid 90s across most of our
area, except cooler at the beaches. Dew points well into the 70s
near the coast will cause heat indices to rise as high as 105-108
degrees, which is borderline for Heat Advisories. If any are issued,
they would be most likely for our coastal counties. Forcing from the
remnant shortwave, departing front, and the afternoon sea breeze
will generate convection. The synoptic models and long range CAMs
are in good agreement, indicating scattered to numerous coverage.
We`ll note that the NBM was an outlier, having POPs up to 80%. This
seemed way too high, so we capped them at 50%, which is still
decent. There doesn`t appear to be as much instability as previous
days. MLCAPEs may struggle to reach 1,000 J/kg across portions of
our area. Even DCAPEs may only be a few hundred J/kg with weak
shear. So a strong storm with gusty winds is possible just about
anywhere, but marginally severe storms appear less likely with this
setup. There will also be the potential for locally heavy rainfall
underneath the thunderstorms due to very weak steering flow and the
potential for training. Convection should gradually decrease during
the evening and overnight. But it`s most likely to persist closer to
the coast overnight. Lows will be in the 70s.

Saturday: Weak mid-level High pressure initially over the Southeast
U.S. will strengthen and build westward as time progresses. It`s
eastern periphery will be over our region overnight. Surface High
pressure will be in the western Atlantic. Meanwhile, weak troughing
is expected to develop over the Southeast U.S. later in the day,
then persist into the night. Deep moisture will prevail across the
region. PWATs should stay ~2.25", which is well above normal.
Similar to Friday, high temperatures are expected to reach well into
the 90s for most areas. Dew points well into the 70s near the coast
will cause heat indices to rise as high as 108-110 degrees, which
would prompt Heat Advisories, most likely for our coastal counties.
Models point to another round of scattered to numerous convective
coverage, especially in the afternoon. Once again, the NBM was the
high outlier, so we went below it and kept chance POPs. Instability
and DCAPEs are similar to Friday. So again, a strong storm with
gusty winds is possible just about anywhere, but marginally severe
storms appear less likely with this setup. There will also be the
potential for locally heavy rainfall underneath the thunderstorms
due to very weak steering flow. Convection should gradually decrease
during the evening and overnight. But it`s most likely to persist
closer to the coast overnight. Lows will be in the 70s.

Sunday: The mid-levels will consist of strong High pressure over the
Southern Plains, with its eastern periphery reaching into our
region. At the surface, High pressure will be in the western
Atlantic, while weak troughing prevails over the Southeast U.S. Deep
moisture will continue to persist across the region. Similar to the
previous two days, high temperatures are expected to reach well into
the 90s for most areas. Dew points well into the 70s closer to the
coast will cause heat indices to rise as high as 112 degrees, which
would prompt Heat Advisories. Instability from the afternoon heat
and humidity will generate scattered to numerous convective coverage
along the sea breeze as it moves inland during the afternoon. Strong
or marginally severe storms are possible along with locally heavy
rainfall.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
Weak fronts or surface troughing will continue to impacting the
Southeast U.S., while High pressure is located in the western
Atlantic. This will lead to diurnal convection with the highest POPs
each afternoon and evening, then trending lower overnight.
High temperatures will be well into the 90s each day and drop into
the 70s each night. Additionally, heat indices could approach 108
degrees along the coast on Monday.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
KCHS/KJZI/KSAV: Flight restrictions are likely at all three
terminals this afternoon with showers and thunderstorms. Storms
should first begin to impact KSAV, before progressing northward
and impacting KCHS/KJZI. A TEMPO group has been included for
each terminal, beginning earlier at KSAV. Precipitation should
end around 04 or 05Z tonight, however lingering clouds could
possibly cause additional vis and cig restrictions. However,
confidence in those impacts is not high enough at this juncture
to include mention in the 18Z TAFs.

Extended Aviation Outlook: Mostly VFR. However, convection could
bring brief flight restrictions, mainly each afternoon and
evening.

&&

.MARINE...
Stout south to southwesterly flow (gusts to around 20 knots) lingers
in the coastal waters through early morning but should weaken
some as we go through the morning hours. Showers and
thunderstorms are likely to impact the coastal waters late this
afternoon through this evening with briefly higher winds and
waves expected. Seas 2 to 4 feet this morning subside slightly
to 2 to 3 feet.

Extended Marine: A typical summertime pattern is expected with High
pressure in the western Atlantic and occasional surface troughing or
fronts over the Southeast. Each day, expect gradually backing winds.
They`ll be strongest along the land/sea interface and across the
Charleston Harbor with the formation of the afternoon sea breeze.
Each night, winds will gradually veer, possibly surging closer to
the coast. Seas will be 2-4 ft.

Rip Currents: A lingering 2 ft, 9 second swell coupled with some
astronomical influences and typical sea breeze enhancements along
the beaches support a moderate risk for rip currents for all beaches
today and Friday.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Heat Advisory until 6 PM EDT this evening for SCZ044-045-
     048>052.
MARINE...None.

&&

$$

NEAR TERM...Adam/CPM
SHORT TERM...
LONG TERM...
AVIATION...CPM
MARINE...Adam