Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 221140
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
640 AM EST Wed Nov 22 2017

.SYNOPSIS...
An area of low pressure will shift NE offshore the NC coast today,
with light rain exiting our forecast area early this morning.
Morning fog and low cloudiness is expected to give way to
decreasing cloudiness this afternoon as drier air works into the
region behind a weak back door front. A series of low pressure
systems will track from the Gulf of Mexico NE across Florida and
offshore the Carolinas late Thursday through Friday night,
providing variable cloudiness along with a slight chance of
light rain, mainly southern and eastern areas. A dry cold front
will cross the region Saturday night, with high pressure
building into the region behind it through early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Mean upper trough axis stretching from the Great Lakes region into
the Gulf of Mexico. Upper disturbance and weak surface low will push
off to our NE this morning. Areas of light rain associated with the
system will push NE out of our forecast area (FA) early this
morning. Moist low levels due to earlier precipitation plus some
enhanced cooling due to drier air moving in aloft, seen on satellite
water vapor imagery, providing dense fog potential. Issued dense fog
advisory for the CSRA/W Midlands. Will monitor for possible
expansion eastward later this morning. Otherwise, expect drier air
to work into our region this afternoon and tonight behind a dry back
door front.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Upper troughiness will continue to extend from the Midwest south
into the Gulf of Mexico. Upper energy will lead to a series of low
pressure areas developing in the Eastern Gulf of Mexico and tracking
NE across FL and offshore the Carolinas, while surface high pressure
builds into the Mid Atlantic. Some uncertainty in play which
reduces confidence on specifics. It still appears that the bulk
of moisture will remain south of our FA through the period.
However, considerable uncertainty in play as models have trended
a little slower and farther south with the first wave and
associated moisture, and are trending stronger and farther north
with the next low and associated moisture. Due to uncertainty,
blended ongoing forecast with latest guidance consensus, which
provides a slight chance of light rain mainly southern/eastern
areas.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Northern stream trough will dig into the E CONUS Saturday, providing
a drier NW flow aloft. Upper energy and a cold front will move
through Saturday night. Current indications are that no
significantprecipitation will be associated with the system.
Dry cool Canadian high pressure will build into the region
Sunday through Tuesday.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
Widespread LIFR conditions this morning but as a cold front
pushes through the area expect improvements by 15z.

Coastal low which brought some light rain to the area overnight
has shifted away from the region but dense fog spread over the
area as dryer mid level air moved atop the moist boundary layer
with light winds. Some improvement already being observed at
DNL/AGS where northwesterly winds already picking up while
CAE/CUB/OGB remain quite low. As the front moves through the
area this morning northerly winds will develop and help mix out
the shallow moisture while drier air advects into the area.

Isentropic downglide combined with diurnal mixing should
eventually help raise ceilings and visibilities by 15z-16z.
Forecasted a return to VFR conditions a little later than most
of the guidance because of the expected northerly surface wind
and inversion. Low clouds should clear by late afternoon with
high clouds still remaining over the area. No restrictions
expected tonight with drier air mass in place and 25 knot low
level jet keeping the boundary layer mixed.

EXTENDED AVIATION OUTLOOK...A frontal zone near the coast with a
series of low pressure centers moving northeastward may help support
MVFR or IFR conditions at times Thursday into Friday but
confidence is low at this time.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
GA...Dense Fog Advisory until 10 AM EST this morning for GAZ040-
     063>065-077.
SC...Dense Fog Advisory until 10 AM EST this morning for SCZ015-016-
     018-020>022-025>031-035>038-041.

&&

$$



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