Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 212332
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
632 PM EST Tue Feb 21 2017

.SYNOPSIS...
Above normal temperatures will continue through the week.
Moisture associated with an onshore flow will support a
chance of showers through Friday. A cold front will cross the
region Saturday with dry high pressure building into the area
for the start of next week.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
An onshore flow will occur in the forecast area associated
with high pressure moving off the Mid-Atlantic Coast and low
pressure in the northeast Gulf of Mexico. Latest CAE radar
indicating a few sprinkles/light showers over portions of the
Midlands and CSRA early this evening. Much of this precipitation
may not be reaching the ground. The lingering effects of upper
ridging will help keep moisture shallow and limit showers. The
high- resolution models display little coverage and we continue
to forecast low pops. The low-level moisture combined with
nocturnal cooling will likely lead to low clouds and fog late
tonight. The temperature guidance was close.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Closed low pressure over the eastern Gulf of Mexico on
Wednesday will gradually shift southeastward and cross the
southern tip of the Florida Peninsula on Thursday. Surface high
pressure over the Mid- Atlantic coast will ridge into the
forecast area from the northeast on Wednesday and will shift
further east into the Atlantic on Thursday. This may promote
weak in situ wedge development on Wednesday in the northern
portion of the area. The wedge may linger just north of the area
on Thursday. Moisture will deepen across the area with surface
winds out of the east/southeast. Precipitable water values will
peak at around 1.3 inches Wednesday afternoon/evening.
Isentropic lift combined with increased moisture transport will
promote a chance of showers on Wednesday. Models show lower
precipitable water values on Thursday with drier air aloft
moving into the region so have continued to indicate only a
slight chance of showers. Kept high temperatures a little lower
on Wednesday with the possibility of a wedge, although still
around 10 degrees above normal. Went with highs on Wednesday in
the lower to middle 70s and middle to upper 70s on Thursday.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
The models take the closed low through the Bahamas on Friday
where it weakens and lifts toward the northeast. A low pressure
system located over the Midwest will track northeastward on
Friday and bring a cold front into the forecast area Saturday.
Models show the front moving through the area relatively quickly
with much drier air returning to the area in the wake of the
front by Saturday evening. Continued to indicate only a slight
chance of pops associated with the front. Surface high pressure
and drier air will settle into the forecast area late Saturday
through Sunday. Modified Pacific air mass with cooler temps but
still projected to be above normal. Nearly zonal upper flow
across the southern states expected to continue late in the
forecast period as well, with systems moving rapidly. A quick
moving trough will track east across the country, with it and
the surface low staying to our north. Surface high to shift east
ahead of it Sun night into Monday, with moisture return for our
area Mon/Mon night into early Tue. Any chance for precipitation
will be low.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Low-level onshore flow will continue across the area overnight.
Models indicating shallow low-level moisture through the night.
The low-level moisture combined with nocturnal cooling will
likely lead to the development of low clouds and fog late
tonight. The guidance was consistent indicating IFR conditions
developing tonight.

The hrrr model shows isolated showers through 06z, and this is
currently being shown on regional radar loops. Will include
mention of vcsh in tafs, although much of the activity will be
light, consisting of mainly sprinkles or a brief light shower.
Remainder of the period after 06z appears mostly dry for now.

EXTENDED AVIATION OUTLOOK....
Moisture associated with an onshore flow may help bring periods
of widespread MVFR or IFR conditions through Friday.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.

&&

$$



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