Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston SC
944 PM EDT Tuesday Sep 2 2014
high pressure will prevail into this weekend. A cold front will
stall and dissipate north of the region by late week...then a
stronger cold front could advance into the region late in the
weekend or early next week.
Near term /until 6 am Wednesday morning/...
a few lingering showers across interior southeast Georgia near the
Altamaha river will continue to dissipate through around midnight...with
rain-free conditions then expected across the area during the
Extensive high level debris cloudiness will remain over the area
into the overnight hours...but should begin to erode late. If
enough clearing does occur...then there is a small potential for
some patchy fog to develop toward daybreak given abundant low
level moisture and light winds. Otherwise expect another warm and
humid night with lows generally in the middle 70s inland and
closer to 80 at the coast.
Short term /6 am Wednesday morning through Friday/...
a deep layer ridge...extending from the Gulf states...eastward into
the Atlantic...will continue to dominate the region through the work
week. This will keep above normal temperatures in the lower to middle
90s each day...and coupled with moderate humidity...will translate
to maximum heat indices of 100-105. These heat indices are below heat
advisory criteria...but still quite uncomfortable.
At the surface...light morning flow will become southeast by
afternoon each day. The lightest winds will be Wednesday...then
expected to become slightly stronger/deeper from the southeast
Thursday and Friday. This pattern is expected to produce isolated to
scattered marine showers/thunderstorms in the late night and
morning...then shift inland with the sea breeze during the afternoons. Have
continued generally chance probability of precipitation inland each afternoon. Cape values
will be at least 2000-3000 j/kg each afternoon. Thus...isolated
strong to possibly severe storms will be possible each day...with
the main impacts being strong winds and large hail.
Given one more day of relatively light steering flow on Wednesday...
could see some locally heavy rainfall amounts and minor flooding. By
Thursday and Friday...the steering flow becomes deeper from the
southeast...which should help keep convection more progressive /less
likely to produce heavy rainfall amounts/.
Long term /Friday night through Tuesday/...
the overall gist of the long term period appears to be a gradual
shift to a more active pattern beginning late in the weekend and
continuing into early next week. The near constant ridge aloft will
weaken over the region as it consolidates to the west and heights
fall aloft as a broad trough sets up across the Great Lakes region
and the Ohio Valley. This will allow for a more significant cold
front to approach the region from the northwest on Sunday and
eventually stall in the vicinity of the southeast coast Monday into
Tuesday. Much deeper moisture will accompany the stalled boundary
and this may lead to a much more active period especially early next
week. As such the forecast features a gradual cooling trend with
temperatures...reaching near normal values by Monday. Also...probability of precipitation
have been increased into the 40 percent range late in the period.
Aviation /02z Wednesday through Sunday/...
extensive high level cloudiness should begin to erode late
tonight...and if enough clearing occurs prior to daybreak then
there is a small potential for some patchy fog to form given
abundant low level moisture and light winds. The best potential
for any fog is at ksav where the most rainfall occurred
earlier...but even here probabilities for reduced visibilities are
too low to include mention in the forecast. Scattered showers and
thunderstorms should develop Wednesday afternoon...but primarily
affect areas inland of the terminals. Otherwise...VFR conditions
are expected to prevail at both terminals through 00z Thursday.
Extended aviation outlook...VFR expected to prevail most of the
week. Brief restrictions to ceiling and visibility will be
possible with early isolated to scattered early afternoon
showers/thunderstorms each day with the sea breeze.
tonight...the local waters will remain between inland trough of
low pressure and offshore high pressure which will maintain S/SW
winds about 10-15 knots.
Wednesday through Sunday...no highlights for winds and/or seas
expected through the weekend as Atlantic high pressure remains
across the area. In general... southeast to south winds of 15 kts
or less and seas 3 feet or less into the weekend.
Waterspouts...conditions may again be conducive for morning and
early afternoon waterspouts...especially Wednesday...but will need
to monitor through the remainder of the week.