Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Columbia SC
138 PM EDT Mon Oct 23 2017
a cold front will bring a chance of showers and thunderstorms
through tonight. A dry, reinforcing cold front will move through
the forecast area Tuesday night bringing cooler temperatures
for mid week. Expect mostly clear skies with a warming trend
through late week. Another cold front will approach the
southeast next weekend.
Near term /through tonight/...
a southern stream closed low will lift from the mid Mississippi
Valley region toward the lower Tennessee/Ohio Valley region
today eventually merging with the broad upper trough. A cold
front will approach the region from the west and begin moving
into the central Savannah River area late this afternoon.
The late morning meso-analysis suggests moderate instability
developing across the csra and southeast midlands where surface cape
now at or above 1000 j/kg. The dew points and surface temps a
little higher than previous thinking resulting in slightly
stronger instability across the southern County Warning Area. This is a concern
suggesting severe potential may be increasing. Showers ahead of
the main front have been mainly light and scattered this
morning aiding further destabilization. 0-1 km storm relative
helicity will be increasing during the afternoon as cold front
approaches from Georgia.
Most of the forecast area has been outlooked by the Storm
Prediction Center in a slight risk for severe weather.
Most of the high resolution models show a line of convection
moving through the area during the late afternoon and early
evening along and ahead of the cold front. Damaging winds are
the primary threat while a brief tornado may also be possible.
Srh values support rotating updrafts. Instability should be a
limiting factor especially across the North County warning area. High
temperatures possibly near 80 across the southeast
midlands...low to mid 70s north.
May still have some lingering showers and thunderstorms this
evening, with the highest rain chances across the eastern half
of the cwa. Rain chances will continue to diminish from west to
east through the night tonight as the cold front moves through
and drier air begins to move in. The main cold front will be
pushing through the forecast area overnight, and will be east of
the area by Tuesday morning. Overnight lows in the low to mid
50s across the western cwa, while eastern counties will only
fall into the upper 50s tonight.
Short term /Tuesday through Thursday night/...
the main cold front and any showers will be east of the area Tuesday
morning. Temperatures on Tuesday will still climb into the 70s as
the coldest air remains west of the area behind a reinforcing cold
front. Expect breezy conditions during the day with BUFKIT wind
profiles suggesting gusts up to 20 mph, under lake Wind Advisory
criteria. Gusts may continue into the evening as the reinforcing
cold front pushes through. Dry weather and slightly below normal
temperatures will prevail through Thursday night. Expect highs in
the mid 60s to around 70 degrees on Wednesday and Thursday. Thursday
looks to be the coldest morning with lows in the upper 30s to low
40s. Although, a moderate 15 kt low level jet (llj) will hinder
frost development in some of our area's cooler spots.
Long term /Friday through Monday/...
little change in the long term forecast. High pressure sitting over
the area early in the period will moderate bringing warming
temperatures and increasing moisture from Friday to Saturday. A deep
upper trough will dig into the southeast pushing another cold front
into the region Saturday or Sunday. Models still disagree on
the timing of the frontal passage. Colder temperatures and dry
weather return for early next week behind the front.
Aviation /18z Monday through Saturday/...
widespread restrictions expected through this evening with
improving conditions tonight as cold front approaches. Gusty
southeast winds to 20 knots shifting to west behind the front.
Ceilings have been slowly rising to MVFR late morning into the
afternoon. Believe ceilings will remain mainly MVFR through
cold frontal passage early this evening as low-level moisture
remains very high. Airmass weakly to moderately unstable ahead
of the front. High resolution models suggest a convective line
will develop along the front with a few discrete cells in
advance of the front. So showers at the terminals more likely
from 20z-24z then diminishing from west to east as front moves
through with ceilings rising to VFR by 02z. Visibility likely
reduced reduced in heavier showers along the front. There is
some potential for patchy fog toward morning especially at fog
prone ags and ogb but confidence low at this time as drier air
mass will be advecting into the area and boundary layer winds
may stay up.
Extended aviation outlook...no significant impacts expected
through the period.