491
FXUS62 KCHS 140737
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
337 AM 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/...
Through Sunrise: An isolated shower/tstm could develop along the
Charleston County coast just before daybreak as a weak land
breeze circulation meanders offshore. Slight chance pops were
maintained in this area to account for this.

Today: The remnants of an old stationary front will finally
dissipate across the interior today as broad upper ridging
holds aloft. The region will remain along the western fringes of
Bermuda high pressure which is centered well offshore of Cape
Hatteras, NC. Convection looks to remain fairly sparse this
afternoon. Despite strong mixed-layer instability noted on
forecast soundings, net moisture values will trend lower
throughout the day with PWATs dropping at or below 2" and 850
hPa theta-e values averaging several Kelvin lower than the past
few days. Little to no forcing is noted aloft with the upper
ridge in place so any convection that fires will be completely
airmass driven and modulated by any convective outflows that are
generated. Modified soundings do show elevated DCAPE values in
excess of 1000 J/kg, so a strong to locally severe tstm can not
be completely ruled out. Pops were limited to slight chance
(20%) for all areas this afternoon with isolated convection
initiating first near/across the coastal corridor then shifting
inland through the late afternoon and evening.

It will be another hot and humid day. Both low-level thicknesses
and 850 hPa temperatures will nudge higher through the day with
current data supporting highs from near 100 across far interior
Southeast Georgia to the lower-mid 90s across the coastal
counties with upper 80s at the beaches. Dewpoints 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. Heat indices
should max out 108-112 east of I-95 with 102-107 farther inland.
A Heat Advisory has been posted for areas along/east of I-95
from noon through 7 PM EDT. A few spots along the Charleston
and Colleton County coasts could see dewpoints pool to 80-81 for
a few hours this afternoon which could briefly push heat
indices to 113-115. These instances should remain fairly
localized and brief, 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 /06Z SUNDAY THROUGH THURSDAY/...
14/06Z TAF Discussion:
KCHS/KJZI/KSAV: VFR. There are some weak signals that an
isolated shower/tstm could pop near the coast just before
daybreak as a weak land breeze develops. This could run in the
vicinity of KCHS and KJZI. Confidence is not high enough to
include a mention at this time. Otherwise, the risk for
isolated, afternoon showers/tstms is too low to include a
mention at any of the terminals this afternoon.

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...
Through Tonight: Southwest to south winds 10-15 kt will prevail
through the period as the waters remain along the western
periphery of the Bermuda High. 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.

Waterspouts: There are indications that a weak land breeze
circulation will emerge off the Charleston and Colleton County
coasts (South Santee River to Edisto Beach) just before daybreak.
Non-supercell tornado parameters along the lower South Carolina
coast are running 2-4 units, so a few waterspouts could develop
along/near this feature before this feature dissipates by mid-
late morning.

&&

.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 from noon today to 7 PM EDT this evening for
     GAZ116>119-138>141.
SC...Heat Advisory from noon today to 7 PM EDT this evening for
     SCZ043>045-047>052.
MARINE...None.

&&

$$