Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 161449

Area Forecast Discussion
National Weather Service Charleston SC
1049 AM EDT Sun Jun 16 2019

Atlantic high pressure will prevail into Tuesday. An inland
surface trough will develop by mid week then persist over the
Southeast into next weekend.


Update: The latest temperatures are running fairly close to the
hourly forecast, so made minor changes to the hourly trend over
the next few hours. The highs appear to be on track. Dew points
are running a little higher than expected, especially near the
coast, so we bumped them up through this afternoon. Models and
CAMs still hint on maybe isolated showers or thunderstorms for
portions of our area this afternoon. We opted to keep the POPs
unchanged and watch the model and observational trends.

Rest of Today: Flat ridging will prevail aloft, while surface
and low level high pressure extends from the Atlantic overhead,
as a subtle lee side trough develops. There is still plenty of
dry air in the H7-H3 layer, but with PWat climbing back closer
to normal for mid June, the sea breeze may have something to
work with to generate showers and t-storms. Since there is still
a cap around H85-H7 and low level lapse rates aren`t that
impressive, we won`t show anything more than 20% POP this
afternoon, mainly across Georgia. Scattered to broken cumulus
clouds will develop, leading to partly or mostly sunny skies
throughout, and with H85 temps of 16-17C, max temps will warm
into the upper 80s and lower 90s.

Tonight: As the surface ridge axis positions itself south of the
area and within a southerly low level flow, it`ll be an even
warmer night, with lows around 2-3F above climo. Marine-induced
showers will make a run for the coast, but with still quite a
bit of subsidence, we don`t have any mention of rain over land.
There will be some fog overnight with favorable condensation
pressure deficits and the lack of mixing, and we have added
mention to the forecast.


Monday: Most of the day will still be under broad upper ridging
although gradually deepening moisture will advect north across
South GA. Temps should warm into the lower 90s inland during the
afternoon with isolated to scattered showers and tstms developing as
the sea breezes pushes inland. We have POPs tapered from 20 percent
Charleston area to 30-40 POPs inland GA where the higher 850 MB
theta-e advection is noted after 18Z.

Tuesday: The upper ridge will give way to a dampening mid level
short wave which is forecast to move from the Tennessee Valley
region early in the day into GA and the Carolinas Tuesday night.
Over our area during the convection initiation hours of the
afternoon, no real stand-out parameters or lifting mechanisms other
than the typical sea breeze and mesoscale boundary are noted. We
maintained chance POPs mostly in the 40 percent range inland from
the coast. Another warm day on tap with temps once again lower 90s
many areas.

Wednesday: Deep layered wind fields will increase as the Piedmont
surface trough develops inland. Conditions appear to favor
convection by afternoon and showers and tstms should translate
toward the coast but it is uncertain where any organization is
possible given model discrepancies at this point. If upstream
tstms develop, they could produce some severe weather as higher
DCAPE values are indicated across the CSRA/Midlands. We will
need more evidence before raising concerns for stronger storms.


A fairly robust mid level short wave is progged to pass through the
southeast states Thursday into early Friday. This appears to be the
most significant period for a potential risk of organized convection
as 700 MB flow increases greater than 30 kt over much of the area.
Timing and convective mode look tricky and global models continue to
show moderate to strong instability at times late week. It still
remains quite uncertain how convection will play out at this
juncture. On Friday, the surface trough will mostly move offshore
and POPs range from slight chance northern SC zones to chance GA.
Upper ridging is expected to build over the weekend with hot and
humid weather and at least a slight chance for afternoon/evening
showers and tstms. Temps on average will run above climo by several
degrees for highs and lows through most of the medium range.


MVFR ceilings are being reported by the CHS ASOS this morning. But
based on a look out the window, we`re keeping VFR in the TAF for
the next few hours. This afternoon, isolated SHRA and/or TSRA
will form on the sea breeze, but the chance of any direct
impacts at either terminal is too minimal to include in the TAFs
at this time. Additionally, patchy fog will develop late
tonight, especially inland from the terminals. Again, no
mention in the TAFs at this time.

Extended Aviation Outlook: Mainly VFR. Brief flight restrictions are
possible in afternoon showers/thunderstorms, especially by mid week.


Today: The Atlantic Ridge will be the dominate weather feature
as it stretches across the local waters. Sea breeze circulations
will back our S and SW winds of 5-10 kt this morning around to
the SE and S as high as about 10 kt this afternoon. Seas will be
no larger than 2 or 3 ft all day.

Satellite imagery shows a line of clouds just offshore this
morning, along the land breeze. But the latest observations
along with webcams show these clouds struggling to gain height
or even dissipating. Hence, the low end risk of waterspouts is
lowering further.

Tonight: The synoptic pattern holds under the influence of
Atlantic high pressure, producing S winds around 10 kt throughout,
with seas to hold in a fairly steady state at 2 or 3 ft.

Monday through Friday: Between high pressure centered offshore and a
trough of low pressure developing inland, winds will veer to
south/southwest and increase in speed during the upcoming week.
Winds of 15-20 knots will become more common by mid week, especially
with the afternoon sea breeze near the coast and during periods of
nocturnal surging, and gusts to 25 knots cannot be ruled out,
especially overnight around midweek. Seas of 1 to 3 ft through
Tuesday will build to 3-5 ft mid to late week.


With the upcoming full moon and onshore winds, minor coastal
flooding is possible along parts of the southeast South Carolina
coast (mainly for downtown Charleston) with the high tide this




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