762 
FXUS62 KCHS 070846
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
446 AM EDT Wed Aug 7 2019

.SYNOPSIS...
A weak surface trough will prevail inland while high pressure
persists across the Atlantic through Friday. A cold front will
approach from the north Saturday, then become stationary over
or near our area early next week. 

&&

.NEAR TERM /THROUGH TONIGHT/...
Pre-dawn: Warm and humid early morning conditions with low-level
southwest flow resulting in enough mixing to keep temps inland 
in the mid 70s with upper 70s common along the coast at 4 AM. 
Mostly clear skies likely to prevail with some patchy layered 
clouds lingering over a few spots. 

Today: Little change to the synoptic pattern today with the deep-
layer trough in place. The morning hours are expected to be mainly
dry with a weak cap in place and strong surface heating
occurring, sending temps to around 90 degrees many areas by 
midday. This afternoon, we expect convection will be slow to 
develop as the upper jet position favors some broad sinking 
aloft with mid level drying was noted on time/height cross-
sections. In the 18Z-21Z time, the majority of CAMs suggest on 
isolated coverage across the area and we have maintained only a 
slight chance POP. In the 22Z-02Z time frame, a weak short wave 
will push through the coastal Carolinas and we have some chance 
POPs across the northern SC zones and Charleston Tri-County area
as moisture is forecast to pool along the sea breeze. Strong 
updraft potential looks to be north of the area during this time
period but isolated stronger storms cannot be ruled out if 
convection develops earlier in the evening. 

It will continue to warm today with low to mid 90s common with
heat indices in the 100-103 degree range most areas. 

Tonight: Isolated showers and tstms may occur late evening prior
to the low level flow veering west after midnight with the formation
of the land breeze and passing of the mid level disturbance. Low
will be in the lower to mid 70s.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
The mid-levels will consist of a trough just off the Southeast coast 
Thursday morning. It will gradually move offshore and 
weaken/deamplify into Saturday as ridging builds over the Central 
U.S., leading to northwest flow over our area. At the surface, a 
weak surface trough will prevail inland while high pressure persists 
across the Atlantic through Friday. A cold front will approach from 
the north on Saturday. The downward trend in moisture continues with 
PWATs falling to roughly 1.5-1.75" Thursday and Friday. Likewise, 
models show much less convective potential Thursday and Friday. We 
lowered the POPs further, keeping slight chance areas to south of 
the Charleston Tri-County area. The best potential for convection 
should be along the GA coast each afternoon for a few hours. Though, 
drier air in the mid-levels may keep a more of the area capped and 
dry than what we're currently showing. During this time frame, 850 
mb temperatures and a late push by the sea breeze will lead to 
daytime temperatures several degrees above normal and mild low 
temperatures. Saturday moisture ramps up quickly ahead of the front 
with PWATs exceeding 2". Likewise, we have POPs ramping up into the 
chance category, especially across our GA counties. It's still a 
little early to determine the convective potential. Instability 
should be in place, aided by lift from the approaching front and 
maybe the sea breeze. However, DCAPEs are not too high, which will 
limit the wind potential. Locally heavy rainfall is also possible. 
But the flooding threat may be limited somewhat by the steering 
winds aloft. 

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
Mid-level troughing will be moving off the East Coast and 
deamplifying Saturday night into Sunday. Meanwhile, ridging will be 
building over the Central U.S., with High pressure centered over the 
Southern Plains. These features will start creeping towards the 
Southeast on Monday while weakening. This should lead to semi-zonal 
flow over our area on Tuesday. At the surface, a stationary front 
will be spread across or nearby our area Saturday night into Sunday. 
The front should dissipate on Monday. Models have trended the front 
further to the north, which was expected. This equates to more 
persistent showers/thunderstorms for much of the long term. Though, 
a shift further north by the front could lead to a slightly drier 
forecast.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions will prevail at KCHS/KSAV through much of Wednesday.
Brief flight restrictions are possible due to showers and/or 
thunderstorms developing across the area Wednesday afternoon/evening,
but confidence remains too low to include mention in the 06Z taf
issuance. 

Extended Aviation Outlook: A front could bring afternoon/evening 
flight restrictions this weekend.

&&

.MARINE...
After a decent nocturnal surge of southwest flow overnight,
winds were subsiding as daybreak nears and will continue to
subside until the flow begins to increase along the SC beaches 
and points offshore after mid afternoon. The surging across the 
waters will peak during the evening and early overnight period 
all waters before late night ebbing. Speeds will reach 15-20 kt
with seas 3-4 ft on average.

Extended Marine: No Small Craft Advisories are expected in the 
extended forecast. The surface pattern will consist of a weak 
surface trough inland while high pressure persists across the 
Atlantic through Friday. A cold front will approach from the north 
Saturday, then become stationary over or near our area early next 
week.

&&

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

&&

$$
NEAR TERM...
SHORT TERM...MS
LONG TERM...MS
AVIATION...MS
MARINE...MS