764
FXUS62 KCHS 141805
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
205 PM EDT Sun Jul 14 2024

.SYNOPSIS...
Atlantic high pressure and a weak inland trough will extend
across the region through the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
This Afternoon: Aloft, a broad ridge will hold across the Southeast
United States. At the sfc, the region will remain along the western
periphery of sfc high pressure positioned over the Atlantic while
lee troughing develops well inland to the local area. Convection
should remain rather sparse and develop a few hours later than the
previous day given a substantial amount of subsidence resulting from
high pressure and a downsloping wind component aloft. This will in
return allow sfc temps to warm a few degrees warmer than yesterday
as well with strong diurnal heating occurring under less cloud cover
and ahead of a somewhat pinned sea breeze.  Showers and/or
thunderstorms that do develop early to mid afternoon should be pulse
type in nature, highly dependent on instability in place given a
lack of shear and forcing mechanisms. The sea breeze could provide a
focusing mechanism for initiating activity by mid afternoon, slowly
shifting inland after being pinned closer to the coast. Although
organized severe weather will remain quite low, a stronger or even
marginally severe thunderstorm can not be ruled out during boundary
interactions in an environment displaying SBCAPE around 4500 J/kg
and PWATs around 2.0 inches closer to the coast, and low-lvl lapse
rates around 8.0-8.5 C/kg and DCAPE values around 1000-1200 J/kg
further inland. An isolated bout of strong/damaging wind gusts brief
heavy downpour will be the primary concern should a stronger
thunderstorm develop mid to late afternoon. Similar to yesterday,
expect convection to wane heading closer to sunset given diurnal
heat loss in a weakly sheared environment. However, it`s not out of
the question for a few showers/thunderstorms to persist along
boundary interactions.

It will be another hot and humid day. Both low-level thicknesses and
850 hPa temperatures will nudge higher through the day with,
supporting highs near 100 across far interior Southeast Georgia to
the lower-mid 90s across coastal counties. Sfc dewpts should mix out
to the mid-upper 60s roughly west of a Hampton-Glennville line with
mid-upper 70s east of the I-95 corridor. Given these conditions,
heat indices should max out in the 108-112 range east of I-95 and in
the 102-107 range well inland. A Heat Advisory will remain in place
for areas along/east of I-95 through 7 PM EDT. A few spots along the
Charleston and Colleton County coasts could see dewpoints pool into
the lower 80s for a few hours, which could briefly push heat indices
to 113-115. These instances should remain fairly localized and brief
before showers and thunderstorms develop near a sea breeze shifting
inland, so an Excessive Heat Warning will not be issued at this time.

Tonight: Any lingering convection should quickly end after sunset
with dry conditions prevailing through the overnight period. It
will remain warm and humid with lows from the mid 70s well inland
to the lower 80s at the beaches and Downtown Charleston.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
The region will be positioned along the western edge of broad
ridging aloft through the middle of the week. At the surface
high pressure will be centered well offshore, building into the
forecast area from the east. Lacking any significant source of
forcing afternoon showers and thunderstorms will be driven by
the local sea- breeze and additional boundary interactions.
Scattered to numerous showers and thunderstorms will be possible
each afternoon. Locally heavy rainfall will be possible, with
limited steering flow and PWATs around or just above 2 inches.

Hot and humid conditions are expected each day, with Heat Index
values of 105-110F forecast each afternoon. Heat Advisories
will likely be required, mainly along and east of I-95. It is
worth noting that afternoon convection would limit Heat Index
potential. Overnight lows will provide little relief from the
warm temperatures, with lows only dipping into the mid 70s
inland and around 80 at the beaches. The record high minimum
temperature could be challenged at the KCHS and Downtown
Charleston climate sites (if convection doesn`t impact the
temperature). See Climate section for more details.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
The ridging aloft will begin to retreat to the east as a mid-
level trough swings towards the East Coast late in the week. At
the surface high pressure will also retreat back over the
Atlantic as a cold front approaches the region. A rather wet
pattern appears to set up late in the week as PWATs increase to
over 2 inches as the cold front approaches. The forecast
currently features scattered to numerous showers and
thunderstorms each afternoon, with PoPs increasing each
afternoon through the period. With the additional cloud cover
and precipitation Heat Index values will likely remain below
Heat Advisory levels after Thursday.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
VFR conditions are expected at CHS/JZI/SAV through 18Z Monday.
However, a few showers and/or thunderstorms could eventually
impact the terminals mid afternoon today along an inland moving
sea breeze, producing TEMPO flight restrictions. Have opted to
maintain VFR conditions for this scenario given limited coverage
across the local area. Afternoon shower and thunderstorms
return across the area Monday afternoon, a few of which could
impact any terminal, but confidence remains too low to include
in the latest TAF issuance.

Extended Aviation Outlook: Scattered afternoon showers/tstorms
could produce brief flight restrictions at all terminals through
the middle of next week. Late week precipitation chances will
begin to increase, increasing the risk for flight restrictions.

&&

.MARINE...
This Afternoon and Tonight: A fairly weak pressure gradient will
prevail along the western periphery of high pressure across the
Atlantic and a trough well inland. South to southeast winds
upwards to 10-15 kt are possible, strongest along the coast. Winds
should then return to southwest overnight. Seas will average
2-4 ft.

Monday through Thursday: High pressure will prevail across the
marine zones through the middle of the week. Thereafter, a cold
front will approach the inland zones, creating a slightly
pinched pressure gradient between the approaching cold front and
the high pressure over the marine waters. However, conditions
are expected to remain below Small Craft Advisory criteria.
Generally S winds are forecast, 10-15 knots. Slightly stronger
wind speeds are possible along the direct coastline in
association with the afternoon sea breeze. Seas should average 3
to 4 ft.

&&

.CLIMATE...
Record High Minimum Temperatures:

July 15:
KCHS: 81/1981
KCXM: 82/2023
KSAV: 80/1981

July 16:
KCHS: 78/2023
KCXM: 82/2021
KSAV: 82/1883

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory until 7 PM EDT this evening for GAZ116>119-
     138>141.
SC...Heat Advisory until 7 PM EDT this evening for SCZ043>045-
     047>052.
MARINE...None.

&&

$$

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