Severe Thunderstorm Warning 128, NWS Charleston, SC

Area Forecast Discussion
National Weather Service Charleston SC
404 PM EDT Sun Aug 21 2022

.SYNOPSIS...
Several disturbances will linger across our region this week.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
KCLX detected scattered to numerous showers and thunderstorms along
and east of I-95 across the SC Lowcountry. Additional cells should
develop later this afternoon and evening as outflow boundaries spread
out across the forecast area and the sea breeze pushes inland.
Latest SPC mesoanalysis indicated that MLCAPE ranged around 2000
J/kg, with low values of CIN lingering off the SC coast. Recent runs
of the HRRR and HREF indicate that coverage will categorical across
portions of the CWA late this afternoon into this evening. Given PW
values around 2.2 inches and slow storm motions, a few areas could
experience flooding of low lying or other poor drainage locations.
In addition, a few strong thunderstorms are possible through early
this evening. Convection should continue across through land-based
zones through this evening, then should slowly shift over the
coastal waters late tonight. Low temperatures are forecast to range
in the low to mid 70s tonight.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
An unsettled weather pattern will persist across our area. The mid-
levels will consist of a trough gradually strengthening/amplifying
over the East Coast into Tuesday, with signs that it's axis may
reform to the west on Wednesday. At the surface, High pressure will
remain far to our east in the Atlantic. Meanwhile, a surface trough
should either be to our west or overhead Monday and Tuesday
afternoon. Additionally, a cold front will be approaching from the
northwest late Monday into Tuesday. The front may be located just to
our northwest by late Wednesday, or possibly beginning to move
through our area. A deep plume of moisture will remain across
region, with PWATs at least 2", and at times up to 2.25", which is
well above normal for this time of year. All of this moisture
combined with the mid-level and surface features, along with a weak
afternoon sea breeze will lead to afternoon and evening convection.
The convection may decrease a bit in coverage and intensity during
the overnights and early mornings, but it's not expected to
completely go away and dry out. Hence, we have POPs as high as
likely during the days and generally in the chance category each
night. It's difficult to determine the exact timing and location of
the convection and rainfall as this will best be determined during
the near term. The main concern each day will be the potential for
locally heavy rainfall, which could lead to flooding in low- lying
and poorly drained areas. The flood potential should worsen with
each passing day as the ground gets more saturated. The overall
severe potential appears to be rather low due to limited
instability, that actually drops with each passing day. But if any
severe storms due manage to form, damaging winds would be the most
likely hazard. Temperatures will be a few degrees below normal due
to the abundant clouds and precipitation.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Broad mid-level troughing is expected to prevail over the East Coast
through Thursday. Heights start to rise on Friday as weak ridging
builds across the southern U.S. The ridge strengthens/amplifies over
the weekend. At the surface, High pressure will prevail far to our
east in the Atlantic. Meanwhile, a weak cold front will slowly
approach from the northwest Wednesday night into Thursday. The front
is expected to move through our area late Thursday, then transition
to a stationary front just off our coast, where it could remain
Friday through early next week. Deep moisture will be in place ahead
of the front, and nearby over the weekend. This pattern will bring
our area unsettled weather in the form of showers/thunderstorms,
especially each afternoon and evening. For this reason, high
temperatures should remain a few degrees below normal.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
Prior to the 18Z TAFs, the terminals have warmed to the
convective temperature and the cumulus field has started to
develop. KCLX detected a few showers and isolated thunderstorms
across portions of the SC Lowcountry and SE GA. Steering flow
should result in the convection to near the coast by 20Z. High
resolution guidance indicates that new convection will develop
along the coast late this afternoon into this evening,
highlighted with TEMPOs generally from 20-1Z. Showers should
linger across the terminals through most of the evening, pushing
off the coast after midnight. On Monday, the day should start
with light SW winds and VFR conditions. However, by mid-morning
showers should develop near the terminals, highlighted with VCSH
by 15Z.

Extended Aviation Outlook: Periodic flight restrictions are likely
due to showers and thunderstorms, especially each afternoon/evening.

&&

.MARINE...
The sfc pattern across the marine zones will support SSW winds
between 10 to 15 kts tonight. Seas are forecast to gradually
increase to 2 to 3 ft.

Extended Marine: An unsettled weather pattern will persist.
Atlantic High pressure will remain far to our east while several
surface troughs or weak fronts gradually move through the Southeast.
In general, winds should mostly be from the SW 15 kt or less through
Tuesday, then shifting around to the SE or E Wednesday and Thursday.
Seas will average 2-3 ft. Additionally, showers/thunderstorms should
bring brief impacts to the coastal waters throughout the extended
marine period.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.

&&

NEAR TERM...NED
SHORT TERM...
LONG TERM...
AVIATION...NED
MARINE...

Hazardous Weather Outlook
National Weather Service Charleston SC
407 AM EDT Sun Aug 21 2022

GAZ087-088-099>101-114>119-137>141-SCZ040-042>045-047>052-220815-
Jenkins-Screven-Candler-Bulloch-Effingham-Tattnall-Evans-
Inland Bryan-Coastal Bryan-Inland Chatham-Coastal Chatham-Long-
Inland Liberty-Coastal Liberty-Inland McIntosh-Coastal McIntosh-
Allendale-Hampton-Inland Colleton-Dorchester-Inland Berkeley-
Inland Jasper-Beaufort-Coastal Colleton-Charleston-Coastal Jasper-
Tidal Berkeley-
407 AM EDT Sun Aug 21 2022

This Hazardous Weather Outlook is for southeast Georgia and
southeast South Carolina.

.DAY ONE...Today and tonight.

Heavy Rainfall: Several rounds of showers and thunderstorms will
impact the region this afternoon through tonight. Heavy rainfall is
possible along with some localized flooding, especially in low-lying
and poorly drained areas.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Heavy Rainfall: Considerable moisture will persist across the area
through early this week, resulting in showers and thunderstorms.
Periods of heavy rainfall are expected and flooding could occur,
especially in low-lying and poorly drained areas.

.SPOTTER INFORMATION STATEMENT...

Spotter assistance is not anticipated at this time.

AMZ330-350-352-354-374-220815-
Charleston Harbor-
Waters from South Santee River to Edisto Beach SC out 20 NM-
Waters from Edisto Beach SC to Savannah GA out 20 NM-
Waters from Savannah GA to Altamaha Sound GA out 20 NM, including
Grays Reef National Marine Sanctuary-
Waters from Savannah GA to Altamaha Sound GA from 20 to 60 NM-
407 AM EDT Sun Aug 21 2022

This Hazardous Weather Outlook is for Atlantic coastal waters.

.DAY ONE...Today and tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter assistance is not anticipated at this time.

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