Special Weather Statement, NWS Charleston, SC

Area Forecast Discussion
National Weather Service Charleston SC
352 PM EDT Mon Jul 16 2018

.SYNOPSIS...
An inland surface trough will strengthen through tonight. A
cold front will move into the area mid week before stalling and
then moving north as a warm front Friday.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Scattered convection will continue into the early evening as a
result of weak upper shortwave energy, high PWATs, and a number
of convective outflow boundaries interacting. Coverage should
diminish later this evening as instability decreases, though the
2"+ PWATs and a continued weak trough pattern aloft favors at
least isolated showers and tstms overnight. Better chances for
convection may exist over the SC waters later tonight, including
coastal SC, coincident with a stronger vort max rotating
through.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
An amplifying upper level trough over the East Coast on Tuesday will
only shift slowly off the coast Wednesday and Thursday. This flow
pattern will maintain very high moisture content air with
precipitable water values from 2.0 to 2.3 inches over the forecast
area at least into Wednesday. Then the models differ some on
maintaining the high precipitable water levels over the area with
the NAM maintaining it through Thursday, the GFS through Wednesday
and the ECMWF and the Canadian models only into Wednesday. Most
models now bring the cold front deeper into or perhaps even just
through the forecast area Wednesday into Thursday before stalling it
out.

With the front a bit further south and the possibility of at least
somewhat drier air moving in the north and west possibly Wednesday
and a bit more likely by Thursday, lowered rain chances a bit in the
west Wednesday and a little more substantially Thursday in the north
and west. With the high precipitable water levels and relative slow
storm motions, feel that there is a decent threat for some heavy
rain on Tuesday. By Wednesday and certainly by Thursday, the threat
for heavy rain would be most likely across southeast Georgia and
coastal southeast South Carolina. Due to cloud cover and relative
quick development of scattered to numerous showers and thunderstorms
each day, think the threat for strong thunderstorms would be quite
low. Highs through the period will be near 90 inland and mid to
upper 80s at the coast. Lows will mainly be in the mid to upper
70s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A stationary front will hover over the region Thursday night.
The stationary front will transition into a warm front and then move
northward on Friday. A trough is expected to develop inland over the
weekend while another cold front slowly approaches. The end result
will be a rainy weather pattern.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
Convective development thus far has been very sporadic and
hasn't lined up well with where the high-resolution models were
initially predicting. Given the recent trends toward convection
developing farther inland, our confidence in either terminal
experiencing a prolonged period of thunderstorms and/or flight
restrictions is low, so we are not currently carrying TEMPO
groups, just VCTS at KSAV and VCSH at KCHS through early eve.
Can't rule out a shower overnight but the best coverage will be
offshore.

Extended Aviation Outlook: A front will bring unsettled weather in
the form of showers and thunderstorms and periodic restrictions
through the weekend, mainly during the afternoon and evening
hours.

&&

.MARINE...
The low-level gradient will strengthen tonight as a shortwave
moves through aloft and high pressure strengthens over the
western Atlantic. Southerly flow will increase to just shy of 15
kt over the waters by late evening.

A tightening pressure gradient between an approaching cold
front to the west and strong Atlantic high pressure should
increase winds Tuesday afternoon and Tuesday night to near 15
knots with some gusts in excess of 20 knots. This will result in
seas building to generally 2 to 4 feet that will persist well
into Wednesday. At the present time, feel winds during this
period will remain below small craft advisory levels. Otherwise,
expect winds to remain below 15 knots with seas mainly from 1
to 3 feet through the period. The front will become stationary
across our area Wednesday and Thursday and then transition into
a warm front and move northward on Friday.

&&

.TIDES/COASTAL FLOODING...
Astronomical influences and onshore winds will produce elevated
tides again tonight. Minor coastal flooding is possible again,
mainly along the South Carolina coast and downtown Charleston
in particular.

&&

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

&&

NEAR TERM...JRL
SHORT TERM...MTE
LONG TERM...
AVIATION...JRL/MTE
MARINE...JRL/MTE
TIDES/COASTAL FLOODING...