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147
FXUS62 KCHS 251923
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
323 PM EDT Tue Jun 25 2024

...AND THE HEAT GOES ON...

.SYNOPSIS...
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High pressure will remain over the western Atlantic while a
weak cold front approaches the area. This front will likely
linger near the area through mid-week, followed by another front
towards the end of the week.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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As of 25/1915z, a few max heat indices include 114 at Beaufort
MCAS (Beaufort), 114 at the Savannah NWR RAWS (Jasper), 113 at
the Sapelo Island NERRS site (McIntosh), 113 at the Midway RAWS
(Liberty), 113 at the Witherbee RAWS (Berkeley), 113 at the
Wambaw RAWS (Charleston), 112 at the Combahee RAWS (Colleton),
111 Savannah UGA Network Sensor (Chatham), 110 at the Charleston
Executive Airport (Charleston), 110 at Summerville Airport
(Dorchester), 109 at Fort Stewart (Liberty), 109 Townsend/Harris
Neck UGA Network Sensor (McIntosh), 108 at the Charleston Intl
Airport (Charleston), 106 at Savannah Intl Airport (Chatham) and
106 at Hunter AAF (Chatham). Refer to the Public Information
Statement (NOUS42 KCHS/PNSCHS) issued at 309 PM for additional
observations.

Heat indices are on target to peak in the 108-112 range across
much of the current Heat Advisory area. A few instances of
113-115 have also ocurred, but appear to be transient and
fairly localized. There are no plans to upgrade any portion of
the advisory to an Excessive Heat Warning at this time, but the
advisory was recently expanded to include Inland Colleton,
Inland Liberty and Inland Bryan given heat indices were at or
just above 108 for a good portion of those zones. Thankfully,
isolated to scattered showers/tstms will begin to cool some
areas off as peak heating approaches.

Convection is starting to pop near and to the east of a weak
surface trough that extended from near Glennville, GA to Hampton
to the Santee-Cooper Lakes. East of the trough, dewpoints are
quite high with readings generally in the lower-mid 70s with
upper 70s/near 80 closer to the immediate coast. While upper
forcing is weak, conditions are favorable for classic airmass
tstms with K-indices running in the lower-mid 30s. DCAPE is
elevated with values roughly 1200-1500 J/kg, so an isolated
strong/severe tstm could occur with damaging winds and cloud-
to-ground lightning being the primary hazards. 20-30% pops look
reasonable for the rest of the afternoon into early this evening
with the greatest coverage still expected to occur in the
Colleton- Berkeley County corridor where the highest pooling of
850 hPa theat-e is occurring. Once convection dies off after
sunset, expect a mostly dry night, although an isolated
shower/tstm could occur just about anywhere at the coast where
warm/moist conditions will linger. Lows tonight will range from
the mid 70s inland to around 80 at the beaches and Downtown
Charleston.
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&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
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Broad troughing aloft will be present over the East Coast of the
U.S. Wednesday and persist through the work week. Similarly, at
the surface a trough will be present along the southeast
coastline on Wednesday. The coastal trough will slowly dissipate
towards the end of the week as high pressure builds in at the
surface from the east. Temperatures at 850 hPa will remain
anomalously warm through the week, with hot and humid conditions
expected each day. Heat index values are forecast to reach
around 103-106F inland, with a few coastal locations possibly
reaching 108F. At this juncture no Heat Advisory is planned,
however conditions will be borderline through the end of the
week. Each afternoon isolated to scattered showers and
thunderstorms are forecast, a typical summertime pattern with
pulse convection. PWATs will remain slightly elevated, around
1.6- 1.7 inches with CAPE values forecast to reach around 1500
J/kg in the afternoon. Therefore, any thunderstorm could become
strong to marginally severe, with damaging wind gusts as the
main hazard.
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&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
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A similar summertime pattern will prevail through the weekend
and into early next week as high pressure builds in aloft along
with coastal troughing at the surface. Isolated to scattered
afternoon showers and thunderstorms will be possible each day,
with hot and humid conditions. Head index values will likely
peak around 103-105F inland with some locations along the
coastline reaching 108F. Head Advisories may be required.
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&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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25/18z TAF Discussion:
KCHS/KJZI/KSAV: Best convective parameters look to occur near
KCHS this afternoon in the vicinity of a weak surface trough.
VCTS was highlighted there through 21z. Otherwise, the best tstm
impacts look to remain west of KSAV and KJZI. VFR will prevail
for the remainder of the 18z TAF period. Some last minute
adjustments may be needed based on radar trends at issuance
time.

Extended Aviation Outlook: Brief flight restrictions will be
possible at all terminals with afternoon showers and
thunderstorms into the weekend.
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&&

.MARINE...
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Tonight: No concerns with southerly winds 5-10 kt and seas 2-3
ft.

Wednesday through Saturday: Generally tranquil marine
conditions are expected through the period. Winds will gradually
back each day and veer overnight, strongest along the coastline
as the afternoon sea breeze/overnight land breeze develops.
Seas should average 2 to 3 ft.
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&&

.CHS WATCHES/WARNINGS/ADVISORIES...
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GA...Heat Advisory until 6 PM EDT this evening for GAZ116-138.
     Heat Advisory until 6 PM EDT this evening for GAZ117>119-
     139>141.
SC...Heat Advisory until 6 PM EDT this evening for SCZ043.
     Heat Advisory until 6 PM EDT this evening for SCZ044-045-
     047>052.
MARINE...None.
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&&

$$