Special Weather Statement, NWS Charleston, SC

Area Forecast Discussion
National Weather Service Charleston SC
727 PM EDT Wed Jul 31 2019

.SYNOPSIS...
Weak high pressure will prevail before a broad area of low
pressure develops over the Coastal Plain late this week into
early next week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Based on recent trends and the fact that the SPC meso-analysis
page still has decent thermodynamics across the area and there
does remain a few boundaries, we have increased coverage of
convection into the scattered range along our northwest tier,
with isolated activity a little further east. Little to no
convection is expected over the coastal corridor. DCAPE is still
in excess of 800 to 1000 J/kg, so gusty winds can occur in one
or two storms. Also, elevated moisture and back
building/training of a few cells will lead to locally heavy
rainfall. All convection will fade by 10 pm.

There are still no solid signals of fog late tonight, so no
mention in the forecast at this time.

We lowered temps in many areas due to the rainfall along our
northwest zones this evening, but no changes to actual low
temps.

Previous discussion...
The forecast area will largely remain under the influence of
Atlantic high pressure tonight, although weak troughing will persist
to the west. Radar imagery late this afternoon indicated shower/thunderstorm
activity just outside of the forecast area. Latest hi-resolution
guidance hints that some of this may drift into the area, but
coverage should remain isolated at best. Any convection and
lingering cumulus should dissipate quickly with loss of solar
heating. The rest of the overnight features a dry forecast with
mainly some passing high clouds overhead. Couldn't rule out some
patchy fog, but probabilities are too low to include mention in
the forecast. Low temperatures will be seasonable, ranging from
around 70 inland to mid/upper 70s at the immediate coast.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
Thursday: The forecast area will remain under a H5 weakness, between
a ridge over the Atlantic and the southern Great Plains. A cold
front is expected to become generally stationary across the southern
Appalachians. SE flow ahead of the front will gradually increase
moisture across the forecast area, afternoon coastal dewpoints
ranging in the low to mid 70s. Short term guidance indicates SBCAPEs
between 1500-2000 J/kg across the CWA. Given high temps in the mid
to upper 90s inland and SE flow, conditions will suit a mid-
afternoon sea breeze. I forecast scattered showers and thunderstorms
along and west of the sea breeze, isolated to the east.

Friday and Saturday: The H5 trough axis is forecast to slide east
across the Southeast region. A sfc trough sourced from the Bahamas
will track NW reaching FL early this weekend. The environment across
the forecast area will see a noticeable increase in moisture, PWs
increasing to 2.0 to 2.2 inches during the period. Increased
conditional instability and lower LCLs should support at least
numerous showers and thunderstorms. Slow storm motions and deep
moisture may support torrential downpours and localized heavy
rainfall. Generally, increasing cloud cover and convection should
favor high temperatures around normal.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A broad trough of low pressure will persist over the area while high
pressure remains offshore, maintaining fairly typical summertime
conditions across the Southeast United States through the middle of
next week. Light southerly winds will maintain ample moisture (PWATs
around 2.0 inches) while sufficient sfc heating leads to high temps
generally in the upper 80s near the coast to lower 90s inland each
day. Given the pattern, chances of showers and thunderstorms are
possible each day, while precip coverage should be slightly less
during overnight periods. Low temps should generally range in the
lower 70s inland to mid/upper 70s near the coast.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
VFR will prevail at KCHS and KSAV through 00Z Friday.

Isolated convection upstream from KCHS will approach but should
fall short of the terminal this evening.

Any potential for flight restrictions in any fog and/or stratus
around 10-13Z Thursday and in isolated SHRA/TSRA between 18Z
and 23Z Thursday is too low to address in the TAF set at this
time.

Extended Aviation Outlook: VFR conditions should prevail at
both terminals through much of Thursday. However, brief flight
restrictions are possible Thursday afternoon/evening at both
terminals due to showers/thunderstorms. Greater chances of
flight restrictions arrive this weekend, mainly due to
increasing coverage of showers and thunderstorms.

&&

.MARINE...
Rather benign marine conditions are expected to continue
through tonight. South/southeast winds this evening will
gradually veer to become more southwest by daybreak. Speeds will
average 10 knots or less with seas less than 3 feet.

Thursday through Monday: The waters will remain between a weak
trough of low pressure inland and high pressure across the western
Atlantic through the rest of the work week. Deep moisture advection
to the area should support scattered to numerous
showers/thunderstorms, but coverage could be greater as a sfc trough
approaches from the southeast during the weekend. Outside of
convection, conditions are expected to remain below Small Craft
Advisory thresholds. In general, south/southeast winds around 10 kt
or less on Thursday should persist through the weekend, then briefly
turn west before returning to south/southeast early next week. Seas
will range between 1-3 ft through Friday, before building to 2-4 ft
Saturday and Sunday. Seas should then subside to 1-3 ft Monday.

Rip Currents: The combination of astronomical influences, a
modest onshore wind with the sea breeze and a 2 ft, 9 second
easterly swell will support a moderate risk for rip currents at
all beaches through this evening.

&&

.TIDES/COASTAL FLOODING...
A Coastal Flood Advisory remains in effect for the entire coast
which will be in effect until 11 PM this evening. Latest tidal
departures have been averaging 0.8-1 ft, so this would place
tide levels in the moderate flooding category. The tide should
peak around 7.6 ft MLLW in Charleston Harbor; 9.6 ft MLLW in
Fort Pulaski.

There remains a potential for at least shallow to moderate
coastal flooding along coastal areas during the evening high
tide cycle through late this the week. During the period, tides
will remain elevated due to the new moon and lunar perigee.
Coastal Flood products will likely be needed for the evening
high tide cycle through late week as a result.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Coastal Flood Advisory until 11 PM EDT this evening for GAZ117-
     119-139-141.
SC...Coastal Flood Advisory until 11 PM EDT this evening for
     SCZ048>051.
MARINE...None.

&&

NEAR TERM...
SHORT TERM...NED
LONG TERM...
AVIATION...
MARINE...
TIDES/COASTAL FLOODING...

Hazardous Weather Outlook
National Weather Service Charleston SC
723 PM EDT Wed Jul 31 2019

GAZ117-119-139-141-SCZ048>051-012330-
Coastal Bryan-Coastal Chatham-Coastal Liberty-Coastal McIntosh-
Beaufort-Coastal Colleton-Charleston-Coastal Jasper-
723 PM EDT Wed Jul 31 2019

...COASTAL FLOOD ADVISORY IN EFFECT UNTIL 11 PM EDT THIS EVENING...

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

.DAY ONE...Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Coastal Flood Advisory.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Coastal Flooding: Due to increasing astronomical influences, at
least minor to moderate coastal flooding will be possible during the
evening high tide cycles through late week. Coastal Flood Advisories
will likely be needed.

.SPOTTER INFORMATION STATEMENT...

Spotter assistance is not anticipated at this time.

AMZ330-350-352-354-374-GAZ087-088-099>101-114>116-118-137-138-140-
SCZ040-042>045-047-052-012330-
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-
Jenkins-Screven-Candler-Bulloch-Effingham-Tattnall-Evans-
Inland Bryan-Inland Chatham-Long-Inland Liberty-Inland McIntosh-
Allendale-Hampton-Inland Colleton-Dorchester-Inland Berkeley-
Inland Jasper-Tidal Berkeley-
723 PM EDT Wed Jul 31 2019

This Hazardous Weather Outlook is for Atlantic coastal waters,
southeast Georgia and southeast South Carolina.

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter assistance is not anticipated at this time.