Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston SC
1106 am EDT Thursday Oct 2 2014
high pressure will persist across the area through tonight. A strong
cold front will then move through the region Friday night...with high
pressure building back over the southeast states through early next
week. A weak storm system passing offshore could bring some rain for
Near term /through tonight/...
today...quiet conditions will continue again...as the forecast
area remains under the influence of deep layer ridging. The
morning sounding at Charleston revealed significant dry air above
the first few hundred feet...and considering sufficient subsidence
within this pattern...expect dry weather to prevail with rain
chances generally zero. Have adjusted dewpoint temperatures to
follow short term observational trends that suggest low level
moisture is slightly higher through middle morning. However...still
expect afternoon mixing to allow dewpoints to fall into the upper
50s inland to low/middle 60s near the coast. Mostly clear to partly
cloudy skies and higher heights aloft will support unseasonably
warm temperatures this afternoon...peaking in the middle to upper 80s
inland. Onshore flow will keep coastal locations notably cooler in
the lower 80s.
Tonight...inland areas should radiate well again...with some fog
development likely after midnight. Numerical models indicate a
potential for increasing clouds toward dawn on Friday...and have
thus introduced only patchy fog at this stage. Low temperatures
for most locales will be in the lower to middle 60s.
Short term /Friday through Sunday/...
Friday...high pressure will shift offshore as a cold front
approaches from the west. The latest model guidance seems to be a
bit slower with the front than 24 hours ago so we think the morning
will generally be dry but rain chances will increase quickly by
afternoon as deeper moisture and forcing for ascent from the upper
trough and jet spreads over the area. Instability still does not
appear to be great although bulk shear around 30 knots is pretty good
for organized convection. Sherb values from the GFS and NAM are
still less than 1 so not favorable for severe storms. The best
chance of any severe storms should be well inland. Highs should
reach above normal in the middle 80s away from the cooler coastal
areas. The front will push offshore Friday night bringing an end to
the rain from west to east.
Saturday...much cooler and drier air mass will move into the region
behind the front. Breezy west to northwest winds will prevail with
some gusts near 25 miles per hour likely given the strong pressure gradient and
cold advection. Highs likely remaining below normal...struggling to
get out of the 70s despite the warming downslope flow. High pressure
will move over the area from the west leading to calming winds and
with little to no cloud cover the stage will be set for improving
radiational cooling conditions by daybreak Sunday. Inland areas will
likely reach the middle to upper 40s with coastal areas lower to middle
50s...about 10-12 degrees below normal. Records at kchs and ksav are
in the middle 40s and upper 40s at kcxm so they should be safe.
Sunday...after a chilly start temperatures will struggle to get warm
up...likely only reaching the lower to middle 70s despite plenty of
Long term /Sunday night through Wednesday/...
high pressure will linger over the area but weaken into middle week as
a dying cold front approaches from the northwest and a wave of low
pressure moves northeast from the Gulf of Mexico and off the Georgia/SC
coasts. Depending on the proximity of the low and amount of moisture
there could be some showers and/or thunderstorms...mainly near the
Temperatures coolest Monday morning...likely back into the 40s
inland...then will gradually modify back above normal. Record lows
Monday morning at kchs and ksav are in the middle 40s and 50 at kcxm so
they should be safe.
Aviation /15z Thursday through Monday/...
VFR weather will prevail at ksav/kchs through 12z Friday...outside
of possible MVFR conditions in light fog closer to dawn on Friday.
Extended aviation outlook...VFR conditions are expected to prevail
Friday through Tuesday except for some late night/early morning fog
and/or stratus prior to middle morning Friday. Also...flight
restrictions will be likely late Friday into early Saturday as a
cold front with showers and thunderstorms moves through. Gusty
west winds expected Saturday afternoon.
today and tonight...high pressure to the north of the waters will
maintain weak onshore flow through tonight...with wind speeds
less than 15 knots and seas 1 to 3 feet...highest well offshore.
Friday through Tuesday...high pressure will give way to a strong
cold front Friday night. Winds will increase a bit Friday ahead of
the front...but more so behind the front late Friday night into
Saturday due to the strong cold advection and pressure gradient.
Should see advisories for all waters during this time. Improving
conditions then on tap late Saturday night/Sunday as high pressure
builds in from the west with tranquil conditions persisting into