Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 170338

Area Forecast Discussion
National Weather Service Columbia SC
1038 PM EST Tue Jan 16 2018

A cold front will cross the area tonight into Wednesday with
some moisture associated with it, bringing a reinforcing shot
of cooler air for late week. Potential for rain/snow mixture
Wednesday as the front moves through.  Moderating temperatures
and increasing moisture are forecast this weekend into Monday.


Tonight: A cold front located west of the mountains this
evening will reach the Midlands late tonight. Latest models
still trending a little wetter along and behind the front.
Temperatures will be tricky tonight. Some weak warm advection
ahead of the front, along with cloudy skies, should keep much of
the forecast area above freezing for the majority of the night.
Concern is for areas across the west and north, where
wetbulbing may bring lows down below freezing as the precip
moves into the area. Top-down tools do indicate precip starting
off as rain, then transitioning to a rain/snow mix as temps
approach freezing across the western and northern Midlands.

Wednesday: The cold front will push through the area during the
morning. Temperatures and precip continue to be the main issues
through the day with the front. Daytime hours should start off with
transition to snow across the west/north, with a rain/snow mixture
possible over the central/eastern Midlands and CSRA. Expect most
areas to eventually transition to a period of all snow at the back
edge of the precip band before it exits the area. Temperatures over
the Midlands and portions of the CSRA will remain above freezing, so
much of the snow should melt with only minor accumulations expected.
However, across the Northern Midlands, Pee Dee, and northern CSRA
models indicating the potential for higher snowfall accumulations.
Areas bordering the SC/NC state line could see between 1-3 inches
through the event, and with temperatures there closer to or below
freezing, higher probability of accumulations sticking. A few
limiting factors include PW values only between 0.5 and 0.75 of an
inch, which leads to some lower confidence in final snow amounts,
along with soil temperatures above freezing which should help melt
some of the initial snow. As for amounts, will probably lean towards
WPC snowfall guidance, with local blend added in.

A Winter Storm Warning continues for Lancaster and Chesterfield
counties. A Winter Weather Advisory generally along and north of
Interstate 20.

Temperatures will be falling with the frontal passage and should
struggle to rise much through the day due to cold advection and
cloud cover. Have indicated high temperatures in the mid 30s north
to around 40 south.


Cool and dry conditions are expected during the second half of the
week. Arctic high pressure will move into the forecast area
Wednesday night in the wake of the exiting cold front and will
reside over the region into the weekend. Strong radiational cooling
with some lingering cold advection will support overnight lows in
the teens to lower 20s Wednesday night with only slightly warmer
temperatures on Thursday night. Temperatures will begin to moderate
on Friday, with highs in the mid 50s. However, Friday nights
temperatures will still fall below freezing due to radiational
cooling, with lows in the mid 20s to lower 30s.


Upper level 500mb flow backs from a zonal westerly flow Thursday and
Friday to a more southwesterly direction over the weekend as an
upper trough over the Gulf of Mexico lifts northeastward and de-
amplifies, and the next digging trough moves into the intermountain
west and Plains states. Surface high pressure will have shifted
offshore by Saturday, allowing for warming southwesterly surface
winds, and daytime high temperatures are expected to be in the low
60s. It will be even warmer on Sunday with highs in the mid to upper
60s. Atmospheric moisture rapidly increases going into Monday with
increasing deep southwesterly flow. There will be a slight chance of
rain showers Sunday night, with rain likely on Monday as a deep
upper trough lifting northeastward from the Plains into the Ohio
Valley and Great Lakes region pushes a cold front into the forecast
area. Yet temperatures will remain mild as Monday`s highs should be
in the 60s and Monday night`s lows in the mid 30s to low 40s.


Deteriorating conditions expected overnight.

A cold front currently located in the Appalachian region will
move into the forecast area overnight. Clouds will increase and
lower as the front moves into the area. By 11z, ceilings are
expected to drop into the MVFR category, with light precip
arriving at CAE/CUB/DNL/AGS. A rain/snow mixture is expected at
CAE/CUB/AGS/DNL with only snow at times, while mainly rain is
expected at OGB. MVFR visibility restrictions will become more
likely with the precipitation. The precipitation is expected to
taper off around 17Z, although low clouds may linger into early
Wednesday evening at CAE/CUB/OGB. Models show ceilings returning
to VFR around 21Z at AGS/DNL. Winds will be variable overnight
as the front moves through the area and will pick up out of the
northwest after daybreak Wednesday at 8 to 12 knots with gusts
around 15 to 18 knots.

EXTENDED AVIATION OUTLOOK...No significant impacts to aviation
expected Wednesday night through Sunday.


GA...Winter Weather Advisory from 2 AM to 5 PM EST Wednesday for
SC...Winter Weather Advisory from 2 AM to 5 PM EST Wednesday for
     Winter Storm Warning from 2 AM to 5 PM EST Wednesday for


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