Area Forecast Discussion
Issued by NWS Charleston, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS62 KCHS 270752

Area Forecast Discussion
National Weather Service Charleston SC
352 AM EDT Tue Jun 27 2017

A stationary front will linger off the coast today. High
pressure will past north of the region Wednesday, then shift
into the Atlantic Thursday. A surface trough will develop inland
on Friday and prevail into the weekend.


A weak stationary front extends roughly along a KTVI-KAYS-
Cox-Shellman Bluff-to ~20 nm east of KHXD per 27/07z surface
analysis. The front will meander slowly south today as high
pressure propagates east across the Ohio Valley. A modest sea
breeze circulation will begin to trek inland later this
afternoon and will be the primary focus for isolated to
scattered showers/tstms. Some early morning convection could pop
later this morning along coastal portions of McIntosh and
Liberty counties in the vicinity of the front, but the of the
convection should hold off until later this afternoon. 20-30%
pops look reasonable for most areas today with up to 40% across
McIntosh County.

Highs will range from the upper 80s inland to the lower 80s at
the beaches where onshore winds will temper conditions. There
are signals that a thick cirrostratus deck will develop after
sunrise, but this should gradually move east and be replaced
with a cumulus field ahead of the sea breeze by peak heating.


Tonight: Any residual convection will quickly dissipate after
sunset. Dry conditions will prevail through the night. Lows will
range from the mid 60s across interior Southeast South Carolina
to the mid 70s at the beaches.

Wednesday through Friday: We`ll get a short break from the typical
summertime heat and humidity Wednesday before it slowly return
Thursday. Shower and t- storm chances are below average
Wednesday, then creeping up Thursday and Friday.

The broad trough in the east lifts out and gives way to building
heights aloft from a building sub-tropical ridge centered near the
NW Bahamas Wednesday that becomes positioned about midway between
Florida and Bermuda Thursday into Friday. Moisture is definitely
lacking Wednesday, with PWAT`s struggling to get above 1" across our
northern zones, or roughly 2 standard deviations below normal. This
is due to dry high pressure to our north holding the moisture to our
south. The high is forecasted to move offshore into the Atlantic
Thursday, allowing SE flow to pump in higher PWATs across our area,
much closer to normal for this time of year. The sea breeze is the
main driver of any diurnal convection during this time, and this
supports at most isolated coverage across interior SE GA Wednesday.
With better moisture Thursday we are forecasting 30-40% POPs, mainly
for SE GA. POPs taper northwards into SE SC where enough dry and
subsidence aloft may remain in place to only allow afternoon CU
development. But by Friday the moisture will be in place across our
entire area. With temperatures topping out near 90 degrees and
plenty of instability in place, POPs range from 40-50%. Isolated
severe storms with damaging winds are possible.


Nearly zonal flow will persist aloft with surface high pressure in
the Atlantic. Southerly flow around the high will advect plenty of
moisture into the Southeast as an inland trough develops this
weekend. The result will be the typical summertime
shower/thunderstorm pattern with the coverage and intensity trending
upwards each day into the weekend.


Generally VFR. Could see a brief period of MVFR vsbys from
fog/stratus at KSAV just before sunrise where dewpoints are

Extended Aviation Outlook: VFR Wednesday. Brief flight restrictions
are possible in afternoon/evening SHRA/TSRA for KSAV Thursday, then
both KCSH and KSAV Friday and Saturday.


Today and tonight: easterly winds will encompass the entire
marine area later today as high pressure remains well to the
north and a weak stationary front lingers to the south. Winds
will remain less than 10 kt with seas 1-2 ft. Expect similar
conditions for the overnight hours.

Wednesday through Saturday: High pressure centered to our north
Wednesday will shift offshore Thursday and prevail in the Atlantic
into the weekend. Easterly winds ~15 kt on Wednesday will veer to
the SE Thursday and ease a few kt as counter-clockwise flow develops
around the high, prevailing through the end of the week. Sea breeze
circulations will give a boost to the winds each day with
shower/thunderstorm chances increasing into the weekend. Seas will
average no greater than 2-4 ft.




$$ is the U.S. government's official web portal to all federal, state and local government web resources and services.