Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 282327
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
727 PM EDT Sun May 28 2017

.SYNOPSIS...
High pressure will linger over the region into Monday. A weak cold
front will gradually sag south across the area prior to midweek.
Atlantic high pressure will extend west over the region late week
into the upcoming weekend.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Severe Thunderstorm Watch 295 has been issued through 1 am for
Berkeley and Charleston Counties, including the adjacent
Atlantic Waters. A line of strong to severe thunderstorms
continues to organize across the Midlands and stretching into
the Pee Dee. High resolution guidance has been consistent in
moving this line east/southeast across the eastern Midlands and
Pee Dee, just brushing the Charleston Tri- county area later
this evening. Watching convective trends carefully as if
convection develops farther south than expected (i.e. due to
convecive outflow/mesoscale boundary interactions), the watch
may need to be expanded south to include Dorchester County. The
cap becomes increasing stronger south of the Edisto River, so do
not anticipate any convection to impact areas south of the
Charleston Tri-county area.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
Monday: While the overall synoptic pattern remains similar, the mid
level flow backs a good bit during the day and we note a decent
increase in moisture between 800 MB and 700 MB during the day. This
will result in an uptick in PWATs, likely weakening the strong mid
level cap during the late afternoon hours. Partly cloudy skies and
warming west boundary layer flow in the morning occur below rather
unstable mid layers, but models still show a good bit of NVA prior
to 21Z Monday. A late day short wave is forecast to move from north
GA into the Carolinas and this should be the main impetus to kick
off deep convection as upper flow trends more divergent toward 00Z
Tuesday. Confidence on how convection plays out is very low, given
some wide variations on the 12Z model runs today. SPC severe
weather outlook for day 2 looks well placed, but may need to
nudged a bit further se to encompass our northwest and north
zones at some point. Until then, isolated severe weather is
possible across our northern GA and SC zones with damaging winds
and large hail the main risks. Another hot day in store with
highs in the low/mid 90s.

Tuesday: A belt of elevated 1000 MB to 850 MB moisture will sag
southeast and further weaken the subsidence aloft while a series of
weak mid level short waves traverse north GA and the Carolinas. The
convective temps should be a bit lower and diurnal convection will
likely be scattered by mid to late afternoon across much of the
forecast area. There may be a few strong to locally severe tstms
given potential boundary collisions and still quite a bit of DCAPE
progged. Highs expected to reach the lower 90s prior to any tstm
development.

Wednesday: The weak cold front may pass offshore by early Wednesday
before washing out and giving way to Atlantic high pressure. Isolated
to locally scattered diurnal convection is possible, especially along
the sea breeze. Deeper moisture may also tend to build from far
south GA during the afternoon and a few showers and tstms could
linger into the evening hours south the Savannah River.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A fairly active period is in store as a quasi-zonal flow exists
aloft and weak shortwave perturbations continually traverse the
area. With increasing moisture through late in the week and
daytime temps in the upper 80s or low 90s, scattered to numerous
showers and tstms expected to develop mainly during the
afternoon and evenings.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
VFR will prevail at both KCHS and KSAV. Thunderstorms are
expected to pass north of the KCHS terminal this evening, but
could get close enough to pose a lightning risk. Will carry VCTS
roughly 02-05z, but the risk for direct impacts are low.

Extended Aviation Outlook: Mainly VFR conditions. Brief flight
restrictions possible in mainly afternoon/evening showers/tstms
starting Monday.

&&

.MARINE...
Tonight: High pressure to the south will maintain a mainly
southwest flow across the local waters, mostly 15 kt or less.
Significant wave heights will be 2-3 feet.

The slightly stronger gradient will persist into Monday with a
decent 15 kt sea breeze in the afternoon, especially north of the
Savannah and along coastal Charleston County. Seas will continue in
the 2-3 ft range. Tuesday and Wednesday, fairly weak winds and small
seas are expected as a front drops into the area and lingers through
mid week. The flow will veer slightly more offshore in the late
night and morning hours as the land breeze oscillation comes and
goes. Atlantic high pressure will dominate into late week with south
to southwest flow continuing.

&&

.EQUIPMENT...
The temperature sensor at KSAV is running high during the
daytime hours. Use this data with caution, especially during
peak heating. The high temperature has been set to missing for
today. Technicians have been notified.

&&

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

&&

$$


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