Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Columbia SC
1050 PM EDT Tuesday Sep 23 2014
a frontal zone will remain along the coast through Thursday.
Near term /until 6 am Wednesday morning/...
the inverted trough will remain off the coast with a pressure
ridge extending southward along the Appalachians tonight. The
models keep deeper moisture associated with the trough east of the
forecast area...but there may be enough moisture combined with
isentropic lift for showers especially in the east section closer
to the deeper moisture. Some of the high-resolution models display
considerable shower coverage throughout the forecast area
overnight but satellite and radar trends support chance probability of precipitation
mainly in the East Part. Used the guidance consensus for the
Short term /6 am Wednesday morning through Thursday night/...
models in general agreement with keeping pesky upper-level cutoff
low across the region through much of Wednesday. At the
surface...high pressure north of the region will bring northerly
winds into the area...with drier air attempting to move in at low-
levels. Best chance for the drier air will be across the upstate
through the period. This is due to a stationary front that will be
situated just off the South Carolina coast through the
period...with an area of low pressure slowly moving northward
along the front. This should spread moisture back into the eastern
County Warning Area. There is some discrepancy in regards to rainfall...with the
GFS/NAM keeping the bulk of the rain east of the County Warning Area...while the
European model (ecmwf) brings the moisture farther west and into the County Warning Area. Leaned
more toward the European model (ecmwf) solution...which keeps moisture flow
along...north...and a little west of the surface low through the
period. Best rain chances will continue to be generally along the
northern coastal plain...but do expect periods of scattered to
numerous showers to be able to push in the eastern and northern
County Warning Area throughout the period. Forecast highs mainly in the lower to
middle 70s Wednesday...and middle 70s Thursday. Overnight lows
Wednesday night generally around 60.
Long term /Friday through Tuesday/...
for the longer term...models show the upper low moving off to the
north of the region into Friday. This may bring weak ridging
aloft into the County Warning Area. However at the surface the winds will continue
out of the northeast...which may be able to bring some Atlantic
moisture into the eastern half of the County Warning Area through much of the
period. Due to this...will continue with a low chance for
rainfall. Clouds should still be somewhat plentiful with this
pattern...and this will keep afternoon temperatures below
normal...with readings in the middle 70s to lower 80s. Expect an
increase in probability of precipitation early next week as an upper trough redevelops
over the lower MS River Valley and low-level moisture increases
from the Gulf of Mexico. Temperatures will be slightly above
normal. Forecast highs will be close to or just below
normal...and forecast lows will be at or just above normal.
Aviation /03z Wednesday through Sunday/...
variable conditions expected through the period.
VFR conditions currently over the taf sites will deteriorate
during the early morning hours as northeasterly winds continue
pushing moisture into the area. Expect MVFR ceilings around 08z...with
potential for IFR around daybreak which will be handled in
upcoming issuances. Conditions will briefly improve to VFR between
14z and 17z with increasing clouds lowering ceilings back to MVFR from
17z through the end of the period. Winds through the period will
be northeasterly at 10 knots...with gusts around 16 knots from 14z
Extended aviation outlook...restrictions possible Wednesday
through Sunday associated with increasing low level moisture.