499
FXUS62 KCHS 142002
AFDCHS

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

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

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Late 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 remains well inland to the local area. Convection
should remain rather sparse during the next few hours given a
substantial amount of subsidence resulting from high pressure and a
downsloping wind component aloft, but could become more focused
along a late afternoon sea breeze shifting inland. Expect the bulk
of showers and thunderstorms to remain pulse type in nature, highly
dependent on instability in place given a lack of shear and forcing
mechanisms. Although organized severe weather will remain quite low,
a strong or even marginally severe thunderstorm can not be ruled out
during boundary interactions within 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 wind gusts
and/or brief heavy downpours will be the primary concerns should
a stronger thunderstorm develop during the next few hours. 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.

Outside of shower and thunderstorm activity, hot and humid
conditions will persist into early evening. Sfc dewpts have mixed
out into the mid-upper 60s well inland where sfc temps have reached
the upper 90s to near 100 degrees. Closer to the coast, temps have
also warmed into the mid 90s for many areas with dewpts remaining
in the mid-upper 70s. The combination of hot and humid conditions
along and east of the I-95 corridor will continue to support a
Heat Advisory through 7 PM EDT. However, some relief can be
expected in locations that experience a shower or thunderstorm.

Tonight: Expect the bulk of convection to wane quickly after sunset
with dry conditions prevailing overnight. Skies will become mostly
clear late and winds will likely become light and/or calm away from
the beaches. However, radiational cooling will be rather weak and
much of the area will experience warm and humid conditions through
the night. In general, low temps will range from the mid 70s inland
to the upper 70s across coastal counties. Along the beaches, low
temps should range in the lower 80s.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
Monday and Tuesday: The region will remain on the western periphery
of a deep layer Atlantic ridge. Generally south-southwest low level
flow with continued hot and humid conditions. Have kept chance PoPs
for afternoon and early evening showers and thunderstorms. Main
initiator of scattered convection will be the seabreeze and other
low level boundaries/outflow boundaries. PWs around 2 inches, along
light steering flow will again bring the potential for locally heavy
downpours with any stronger showers/thunderstorms.

Guidance continues to indicate Heat Advisory conditions will be
likely on Monday and less likely on Tuesday. Highest heat indices
along and east of I-95. Will not issue any Heat Advisories at this
point for Monday, given we already have one in place for
today/Sunday.

Wednesday: The deep layer Atlantic Ridge starts to retreat a bit
eastward as a broad upper level trough forms well northwest of the
region, over the Great Lakes and OH River Valley regions. Given a
little more cyclonic upper level flow, and continued deep/tropical
moisture with PWs 2+ inches, expect higher coverage of convection
than previous days. However, given it is still day 4, have capped
PoPs at high end chance. Given higher convective coverage, feel max
Heat Indices will remain just below Advisory, although cannot rule
out a few spots reaching the 108 threshold.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A weak upper level trough gradually weakens to the northwest of the
area, while a deep layer Atlantic ridge gradually builds back
westward. Model guidance continues to be rather bullish with PoPs in
the likely or even higher categories for much of this period. Given
the typical uncertainty this far out, have continued to undercut
blended model PoPs a tad, keeping them in the high chance to low end
likely range. Temperatures near to possibly slightly below normal,
especially the max temperatures, due to higher than climo PoPs/cloud
cover potential.

&&

.AVIATION /20Z 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: Through mid week: Brief flight restrictions
will be possible with scattered afternoon showers/tstorms at
all terminals, mainly late morning through early afternoon.
Chances for showers/thunderstorms may begin to increase a bit by
mid week, increasing the risk for flight restrictions.

&&

.MARINE...
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 this evening, before winds tip back to southwest overnight.
Seas will average 2-4 ft.

Monday through Tuesday night: No highlights are expected as a
deep layer Atlantic ridge remains centered east of the waters.
Expect south- southwest winds of 15 knots or less and seas of 2
to 4 feet, highest beyond 10 or 20 nm offshore. Scattered mainly
late night through morning showers and thunderstorms.

Wednesday and Thursday: Models show the low level pressure gradient
to increase as an upper level trough develops well northwest of the
waters over the OH River Valley and Great Lakes. South-southwest
winds of 10-20 knots, with some gusts of 20-24 knots possible. Seas
3 to 5 feet, highest well offshore. Still feel conditions will
remain below SCA levels. Scattered to numerous mainly late night
through morning showers and thunderstorms.

&&

.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/RFM
SHORT TERM...RFM
LONG TERM...RFM
AVIATION...DPB/RFM
MARINE...DPB/RFM