Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Columbia SC
1240 PM EDT Thursday Sep 18 2014
high pressure will bring drier weather and below normal
temperatures to the area into the weekend. Another cold front
will bring a chance for showers and thunderstorms early next week.
Near term /through tonight/...
persistent low cloudiness expected to slowly erode through middle
afternoon. Upper trough to remain over the region. Diurnal heating
along with any low level convergence near any boundaries such as
surface trough or differential heating boundary expected to lead to
some possibilties of showers or isolated thunderstorms. Moderate
instabilities along the southern forecast area and some middle level dry air may
provide an isolated severe cell across that area...though threat is
not as great as yesterday. Lingering low level moisture may provide
some fog and low cloud development again late tonight.
Short term /Friday through Saturday night/...
broad upper trough over the eastern Continental U.S. Will shift east on
Friday with an area of low pressure developing over coastal
Georgia. Surface high pressure will shift east across New England
on Friday and move off the East Coast on Saturday. This area of high
pressure will wedge into the forecast area on Friday and persist
into Saturday. Moisture appears relatively shallow so have kept
probability of precipitation low. Highs will be several degrees below climatology under
The Wedge setup with highs in the upper 70s north and lower 80s
south. Winds will generally be out of the east/northeast.
Long term /Sunday through Wednesday/...
an upper trough over the Great Lakes region will dig toward the
southeastern Continental U.S. Early next week. Low pressure off the southeast
coast will deepen and move north along the eastern Seaboard
Sunday and Monday. Low pressure will move east through
southeastern Canada on Monday dragging the next cold front across
the forecast area. Warm air advection and increasing moisture are
expected ahead of the front. Low chance probability of precipitation Monday as the front
crosses the forecast area. Maximum temperatures on Monday are expected
to reach the lower 80s north to upper 80s south. Cooler and drier
air will reach the forecast area by Tuesday morning in the wake of
the front. GFS precipitable water values drop down to below half
an inch. Maximum temperatures on Tuesday are expected to be around 5
to 7 degrees cooler than on Monday. Dry high pressure will remain
in control Tuesday and Wednesday. Lowered probability of precipitation across the northern
forecast area on Wednesday where onshore flow is weak compared to the
southern forecast area.
Aviation /18z Thursday through Tuesday/...
MVFR conditions will slowly give way to VFR by middle afternoon...as
persistent low cloudiness very slowly lifts and dissipates. Daytime
heating expected to lead to isolated to widely scattered showers and
possibly a thunderstorm over portions of the region from middle
afternoon through evening. Confidence of such affecting terminals
too low to include in the tafs at this time. Light winds generally
out of the northeast through the day. Otherwise light and variable
during the night period. Low clouds and/or fog expected to develop
again late tonight through Friday morning...with a slow return to
VFR expected by Friday afternoon.
Extended aviation outlook...late night and morning fog/stratus possible