Area Forecast Discussion
Issued by NWS Charleston, SC
FXUS62 KCHS 300830
Area Forecast Discussion
National Weather Service Charleston SC
430 AM EDT THU JUN 30 2016
A stationary front will linger inland through tonight while weak
upper level disturbances cross the region. Atlantic high pressure
will return to the area late this week and this weekend. Then to
the north early next week a nearly stationary front will become
aligned west to east while Atlantic high pressure prevails along
the Southeast coast.
.NEAR TERM /THROUGH TONIGHT/...
Pre-Dawn: A very weak mid level short wave along with quite a bit
of low level moisture and speed convergence resulted in a
nocturnal expansion of showers and tstms over the atlc waters
where instability remained maximized. A few of the showers and
storms brushed the beaches and near-coastal parts of Charleston
County. Elsewhere, areas of layered clouds resulting in mostly
clear to partly cloudy skies. Will have included some patchy fog
mentions in the the forecast until shortly after dawn as a few
areas were reporting either ground fog or low stratus. Mild and
moist conditions prevailing with temps in the low to mid 70s well
inland to the mid and upper 70s immediate coastal locations.
Today, the overall synoptic pattern favors unsettled weather once
again as similar features to yesterday remain in place. A nearly
stationary front remains displaced across inland South Carolina
into the Sandhills of North Carolina while a ribbon of deep moisture
lingers across most of our forecast area. Forecast pwats values
around 2 inches are indicative of the deep moisture in play. A
45-60 kt 250 mb jet extending from upstate South Carolina to the
mid Atlc region with broad upper difluence still evident on the
right entrance region of this upper jet. Differential heating
along with lingering convective boundaries and the sea breeze
oscillation will all focus initiation late this morning into
early/mid afternoon. Scattered to locally numerous showers and
tstms are expected to develop during the afternoon with pulse and
multi-cell convective modes anticipated. The main threat for
isolated severe weather appears to be damaging winds as a result
of wet microbursts or perhaps outflow driven multi-cell collisions
and propagation. Tstms will again produce locally torrential
downpours resulting in minor flooding. A fairly stout astronomical
high tide will occur around 21Z-22Z today and any heavy rains
falling right along coastal areas could result in more substantial
flooding. Forecast confidence in this occurring is extremely low
given a very complex mesoscale in place.
No significant changes to forecast highs today ranging from upper
80s to lower 90s.
Tonight...Diurnal convection should diminish in coverage and
intensity this evening but with weak upper disturbances aloft and
moisture convergence shifting to the Carolina coast late, we
cannot rule out some nocturnal near-coastal convection once again.
Lows will be in the mid 70s many areas with a few lower 70s
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
Friday through Sunday: The pattern aloft will flatten out and
transition to more zonal as a vigorous trough cross the Great Lakes
region. Then late in the weekend, the large subtropical ridge to the
east will begin to build more into the Southeast. At the surface, a
pretty typical summertime pattern will prevail with Atlantic high
pressure extending into the area. By late in the weekend a nearly
stationary front to the north will become aligned west to east, but
is generally progged to remain well removed from the forecast area.
Daily rain chances through the period will be driven by diurnal
heating and will feature rather garden variety afternoon/evening
showers and thunderstorms. The severe threat doesn`t look
particularly interesting on any one day, but a few strong to
marginally severe storms will be possible each afternoon and evening
especially where boundary interactions occur. Temperatures will
feature highs in the low to mid 90s each day with lows in the mid to
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
The overall thinking for the long term remains the same though the
most recent models runs have trended a bit further south with the
nearly stationary front situated to the north. The large subtropical
ridge still looks to build in from the east early in the week, with
a shortwave progressing into the Appalachians within the zonal flow
to the north. Ultimately, how far south this trough can penetrate
into the ridge will determine how active the pattern is for Tuesday
into Wednesday. The thinking is still that the ridge will remain
strong enough to keep the period relatively dry and hot. In fact,
chances look good for seeing upper 90s by mid week.
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
For the rest of the night, mainly VFR. Isolated to scattered
showers and tstms are expected to brush Charleston County and
may result in some VCTS/VCSH at KCHS overnight along with patchy
MVFR cigs. Cannot rule out some low stratus again at KSAV late
tonight but the greatest chance will be farther inland close to
the retreating surface front. Scattered diurnal showers and
tstms will redevelop along the coastal corridor once again this
afternoon. Currently timing and coverage uncertainties preclude
any TAF mentions at this time.
Extended Aviation Outlook: Flight restrictions are possible within
any showers/thunderstorms through the period. Outside of convection,
mainly VFR conditions are expected.
Through tonight, a s to sw flow will continue to dominate. Speeds
will be light much of today but look for typical late day and
nocturnal surges with speeds increasing to near 15 kt at times.
Seas will average 2 to 3 ft through daybreak Friday.
Friday through Monday: Atlantic high pressure will prevail across
the local waters through the period which will drive a persistent
south to southwest flow. Winds could get as strong as 15-20 knots at
times, mainly along the land/sea interface each afternoon with the
seabreeze and within some modest nocturnal surging. Seas will
generally range 1-3 feet through the period, though 2-4 feet will be
possible by Monday as the pressure gradient tightens along the
The upcoming Perigee occurs early Friday and the New Moon occurs
Independence Day. This scenario will support elevated tides, with
shallow coastal flooding possible late this week into early next
week. The afternoon high tide today could approach 7 feet in