Scientific Forecaster Discussion
fxus62 kchs 230105
Area forecast discussion
National Weather Service Charleston SC
905 PM EDT Thu Jun 22 2017
Atlantic high pressure will give way to a cold front
which will move into the area Sunday. The front will slowly push
offshore as high pressure brings drier conditions for mid to late
Near term /until 6 am Friday morning/...
early this evening: afternoon convection has been waning for the
last few hours. The heavy rain event that set up over Moncks
Corner has now diminished to just some residual light rain. A
few thunderstorms did manage to make it across the Altamaha
river into the area, but have also been weakening. Once this
remaining activity diminishes completely, the rest of the night
is expected to be rain free. We will likely hang on to at least
mostly cloudy conditions for much of the night, mainly in the
form of mid and high level clouds. There could be some stratus
around, but primarily closer to sunrise and it doesn't appear to
be too low. With the considerably cloud cover, fog is not a
significant concern. Lows will only fall into the low to mid 70s
in most areas.
Short term /6 am Friday morning through Sunday/...
the area will remain on the western fringes of Atlantic high
pressure through Saturday before a cold front approaches Saturday
night and pushes into the local area Sunday. Expect low
shower/thunderstorm chances Friday, mainly during the afternoon as
the sea breeze pushes inland as highs get back closer to normal in
the lower 90s inland. High humidity will support heat indices
slightly over the century mark away from the coast.
Rain chances will go up Saturday, mainly for areas to the north and
west toward the Pee Dee/midlands, as deeper moisture returns ahead
of an approaching cold front. Deep layer shear will also be on the
increase and could support a few severe storms. Stronger southerly
winds will help boost temperatures a bit higher into the mid 90s
especially across southeast Georgia where the least cloud cover is
likely. Heat indices once again should peak in the lower 100s
inland. The front should near inland areas by Sunday morning keeping
elevated rain chances across the area Saturday night with lows
remaining quite mild in the mid to upper 70s, although could be a
bit lower depending on the amount of rainfall.
High chances of showers and thunderstorms will continue Sunday as
the front slowly moves through the area. The severe storm risk looks
low overall, mainly confined to southeast portions of the area into
Georgia where instability should be a bit greater. Highs should be held
down a bit in the upper 80s most locales except toward the Altamaha
river where lower 90s are expected.
Long term /Sunday night through Thursday/...
Atlantic high pressure will extend over much of the southeast
this weekend before a cold front associated with the remnants of
Tropical Storm Cindy approaches the area early Sunday into
Monday. At this time, chances of showers and thunderstorms are
forecast over the entire area, but greater coverage of precip is
possible as pwats in excess of 2.0 inches occur during the
timing of fropa. Scattered showers and thunderstorms could
linger into early next week as the front slowly shifts offshore.
However, dry and slightly cooler conditions are anticipated
during the middle and later half of the week as high pressure
builds over the region. In general, high temps should peak in
the mid 80s under some clouds Monday and Tuesday, then warm a
degree or two Wednesday and Thursday under more sunshine.
Overnight lows will range in the low/mid 70s Sunday night, then
upper 60s/lower 70s through the middle of next week.
Aviation /01z Friday through Tuesday/...
an area of MVFR ceilings has developed at kchs, but isn't
expected to last for an extended period of time. Have included a
tempo through 02z. Overnight, model guidance does hint at
marginal MVFR ceilings at both sites, but opted to keep the
forecast VFR for now. Could still see temporary MVFR ceilings
around sunrise for a couple of hours. Then in the afternoon,
showers and thunderstorms are expected to remain inland of kchs
Extended aviation outlook: VFR conditions should then prevail
into Saturday. Better chance of restrictions will come Saturday
night and persist through early next week as a cold front
slowly moves through.
tonight: south winds will continue between 10 to 15 kts tonight.
Wave heights are forecast to range from 2 to 4 feet through the
overnight hours, greatest across amz374. Convection is expected
to remain near the coast this afternoon, then spreading inland
through this evening.
Friday through tuesday: Atlantic high pressure will remain east of
the waters into the weekend before a cold front moves through Sunday
night into Monday. Winds will remain elevated into Sunday ahead of
the front, possibly reaching advisory levels mainly across the
Charleston County nearshore waters Friday night/Saturday. Seas will
build as well but should stay below advisory criteria of 6 feet.
Rip currents...increasing astronomical influences and onshore winds
will lead to an enhanced risk of rip currents across area beaches
through late week.
tides will be running high given the increased astronomical
influences and onshore winds could help push levels high enough
to produce shallow coastal flooding around the times of the
evening high tide through the weekend, especially along the
South Carolina coast.