Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 051419

Area Forecast Discussion
National Weather Service Columbia SC
919 AM EST Mon Dec 5 2016

A storm system along the Gulf Coast will move northeastward to
the Ohio valley spreading widespread rain over the forecast area
tonight into Tuesday. Dry high pressure will briefly build across
the area for Wednesday. Another cold front will cross the region
Thursday bringing much colder air for the end of the week.


Surface high pressure will ridge into the forecast area from the
north today.

Observation trends and models continue to indicate temporary
weakening isentropic lift as an upper-level ridge builds over the
southeastern states in response to a digging area of low pressure
in the Southern Plains. We will see some scouring out of the in
situ wedge and associated low cloudiness. Support for rain today
will be weak. The high-resolution models display just scattered
areas of rain. There is uncertainty with the temperature forecast
today with lingering wedge conditions but breaks in the cloudiness.

The rain chance should increase tonight. The water vapor imagery
indicated upper lift upstream which should reach the forecast area
tonight. We have forecasted categorical pops. Expect little
temperature change.


The closed low crossing the Southern Plains will open and shift
northeast to the Mid Atlantic states tonight through Tuesday.
At the surface, low pressure over the Gulf Coast will track
northeast to the Ohio Valley while another area of low pressure
develops off the NC coast. Models show upper lift and isentropic
lift combined with abundant atmospheric moisture returning to the
forecast area this evening providing widespread rain tonight into
Tuesday morning.

The surface wedge front south of the CSRA may lift northward
into southern SC Tuesday afternoon as a warm front, due to a
strong SW 50 kt low-level jet. There is still some question as to
how far north the wedge boundary/warm front can get. Instability
and shear associated with this boundary could could provide a
severe threat across that area.

Dry air will begin to work its way into the region from the west
during the afternoon Tuesday...ending precipitation. Dry
conditions are expected Tuesday night as the storm system moves
out to sea. There could be a large range in temperatures on
Tuesday due to the position of the warm front. Have indicated
highs in the lower 50s North Midlands to lower 70s CSRA and
Southern Midlands. Kept lows Tuesday night near guidance consensus
     ranging from the lower 40s north to around 50 south.


Wednesday through Thursday Night...Behind the departing system,
drier air will move in aloft on Wednesday, but low cloud could be
slow clear. Still expect dry weather Wednesday and Wednesday night.
An upper impulse will ride across the southern tier of states and
across our region Thursday. A cold front will move through our
region Thursday. Models indicating just enough moisture associated
with front and upper impulse to warrant slight chance POPs.

Friday through Sunday...A broad trough will still be over the
eastern U.S. on Friday, but a dry northwest flow will develop over
the local area. Much cooler air will therefore be advected into
the region and daytime highs Friday and Saturday will only be in
the 40s, with overnight lows in the 20s. However, it will warm
back into the 50s on Sunday as the upper level flow shifts to the
southwest. Sunday now looks to remain dry, as does most of the day
Monday. Yet there is uncertainty in how fast the next weather
system will arrive. At this time, both the 00Z GFS and 00Z ECMWF
keep precipitation west of the area until at least Monday night.


Diminished isentropic lift will occur today. The h85 jet mainly
responsible for low cloudiness last night has shifted northeast of
the area. The h85 flow has become westerly. However, the latest
analysis indicated some low-level convergence in the south so the
lowest cloudiness may linger at OGB, AGS, and DNL. Mainly
followed the GFS LAMP for the ceiling forecast today. Expect
widespread IFR conditions tonight. The water vapor imagery
indicated upper lift upstream that will move into the area
tonight. An associated h85 jet will also overspread the area.
Shear will be on the increase associated with this jet with the
wedge front just south of the area. Followed the NAM and
forecasted LLWS developing.

EXTENDED AVIATION OUTLOOK...Expect widespread IFR conditions
associated with a warm front through Tuesday. Drier conditions are
expected Wednesday, but then a cold front may bring more showers
and associated restrictions Thursday. Breezy conditions may also be
associated with the front.




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