Area forecast discussion
National Weather Service Columbia SC
545 PM EDT Tuesday may 21 2013
Synopsis...
high pressure off the southeast coast will circulate a moist
southerly flow into the forecast area ahead of a slow moving cold
front through Thursday. The cold front will move through the area
Thursday night. The dry air mass behind the front will dominate
during the weekend.
&&
Near term /until 6 am Wednesday morning/...
satellite and radar trends at 2145z indicate scattered thunderstorm
focus now in the csra early this evening. Probability of precipitation decreasing to the
north across the midlands. Thunderstorms should diminish during
the next couple of hours.
Overnight...which should aid in at least some patchy fog
formation late tonight. Lows will fall into the middle 60s.
&&
Short term /6 am Wednesday morning through Wednesday night/...
Wednesday and Wednesday night...low pressure will continue moving
through the central Great Lakes with high pressure off the middle
Atlantic coast. This will continue the southerly winds and
moisture advection into the area along with instability. Result
will be another round of afternoon and evening convection with the
greatest potential across the eastern midlands. With precipitable water values
remaining in the 1.6 to 1.7 inch range the possibility of heavy
rainfall will be the main threat causing standing water in low
lying and poor drainage areas. With the upper trough moving away
from the area and upper heights rising slightly temperatures will
be slightly higher with middle 80s for most locations. Convection
will diminish with sunset...however with the cold front
approaching from the west there is some potential for showers and
thunderstorms Wednesday night mainly over the western midlands.
Overnight lows will generally be in the middle 60s.
Thursday and Thursday night...Thursday will see another chance of
showers and thunderstorms as the cold front crosses the region.
Although models differ slightly on timing of frontal passage indications are
for late morning to early afternoon. This will allow the best
heating over the eastern midlands along with the best chance of
convection. Precipitable water values will again be in excess of 1.6 inches
continuing the threat for heavy rain. The front will move offshore
during the afternoon hours with the chances of showers diminishing
rapidly through the evening hours as drier air begins to push into
the forecast area. Daytime highs will be in the middle 80s with
overnight lows in the middle 60s.
&&
Long term /Thursday through Tuesday/...
models are in good agreement through the long term with some
location differences appearing for Sunday into Tuesday. Pattern
will remain active as high pressure and drier air move into the
area on Friday and Friday night. On Saturday afternoon the high
will slide so the southeast as the next low pressure system slowly
tries to develop over the central US. This will push a frontal
boundary toward the region on Sunday...with the GFS keeping the
front further north and the European model (ecmwf) having the front along the NC/SC
border. By Monday the GFS has pushed the front into southern NC
with the European model (ecmwf) over the northern midlands. Have gone with a
compromise of the European model (ecmwf) and GFS for the latter half of the long
term which currently keeps the area rain free through the end of
the long term...however confidence is low for Sunday through
Tuesday. Temperatures through the long term will be near normal.
&&
Aviation /22z Tuesday through Sunday/...
enhance cumulus field in north/south moisture band situated close to
all taf sites this afternoon will help aid in isolated and
scattered shower/storm development through the afternoon and early
evening hours. Confidence not enough to put in any tafs at this
time. Would look like the best chance for any activity would fall
across the cae/cub/ogb sites...with slightly lower chances at ags/dnl.
Scattered to broken clouds around 3kft should diminish after
sunset...with mostly scattered clouds through midnight. Late
tonight...low-level moisture will remain high. BUFKIT soundings
indicate that a low-level jet around 20 knots will setup across the
taf sites...which should help limit any widespread fog formation.
Should see some scattered low clouds develop once again towards
morning...and would not be surprised to see a stratus deck develop
at sunrise. Will hint at that in tafs with low scattered clouds.
Later shifts should be able to analyze the low stratus/fog
potential better.
Extended aviation outlook...scattered showers and thunderstorms...mainly
afternoon and evening...possible through Friday. Late night/early
morning fog/stratus also possible.
&&
Cae watches/warnings/advisories...
SC...none.
Georgia...none.
&&
$$
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