Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 281145

Area Forecast Discussion
National Weather Service Columbia SC
645 AM EST Tue Feb 28 2017

A warm southerly flow between offshore high pressure and an
approaching cold front will continue through Wednesday. The cold
front will move through the forecast area Wednesday night.
Thunderstorms may be associated with the front late Wednesday
afternoon and night. It will be windy just ahead of the front
Wednesday. Cooler conditions will follow the front for the end
of the week.


A weak warm front will bring low clouds and areas of fog early
this morning. The front should dissipate later this morning and
with heating and mixing plus just shallow moisture expect
considerable sunshine and a warm day. The temperature guidance
was consistent with highs mainly in the lower 80s and just below
records for the date. Moisture has become shallow behind the
mid-level shortwave trough that has moved through the forecast
area. The models indicate moderate instability today. The NAM
has surface-based LI values -5 to -6 but with just shallow
moisture and the dissipating surface feature the thunderstorm
chance is very low as supported by the NAM, GFS, and ECMWF MOS
plus high-resolution models.

The shower and thunderstorm chance should remain very low
tonight with continued shallow moisture and much of the lift
associated with a mid-level shortwave trough staying north of
the forecast area. Low-level moisture and weak isentropic lift
may lead to stratus and fog tonight with stratus favored because
of boundary layer wind. Warm advection and mixing should help
hold up temperatures. The temperature guidance was close with
lows around 60.


The main issues Wednesday will be windy conditions ahead of a
cold front and possible severe thunderstorms late Wednesday
afternoon and night.

The models depict a strong low-level jet ahead of the cold front
Wednesday with h85 winds 40 to 50 knots. There should also be
strong warming and instability ahead of the front. The NAM
displays surface-based LI values around -6. Associated strong
mixing should lead to windy conditions. The NAM Bufkit momentum
transfer tool supports gusts near 30 knots Wednesday afternoon.
A lake wind advisory will likely be needed. Convergence ahead of
the front may lead to a band of showers and thunderstorms and
with continued high shear and possible moderate instability
lingering into the night severe thunderstorms may occur. A
limited factor may be mid-level capping as shown by the NAM and
GFS during the day Wednesday and diminishing instability with
the loss of heating Wednesday night. The SPC WRF indicated a
diminishing area of showers and thunderstorms moving into the
forecast area Wednesday night. Drying behind the front should
dominate Thursday.

Leaned toward the higher temperature guidance ahead of the front
Wednesday. A near record high for the date should occur. The
higher guidance may be better Wednesday night because of mixing
associated with the front. Followed the guidance consensus
temperature Thursday.


The GFS and ECMWF show dry high pressure building into the
forecast area from the northwest through Friday with the high
near the area Saturday and off the coast Sunday and Monday. The
GFS and ECMWF plus GFS ensemble mean have pops less than 20
percent through Sunday, and 20 percent or less Monday. The MOS
indicates the coldest air Sunday with lows near freezing.


Restrictions in stratus/fog will improve to VFR later this
morning. Restrictions will be possible again early Wednesday in
mainly stratus.

Increased low level moisture associated with a warm front in the
area is promoting stratus development this morning. Some of the
stratus has become scattered, but satellite imagery shows
another area of low stratus that could potentially affect
CAE/CUB. Confidence was too low to include. Stratus may linger
this morning, but as the warm front pushes north, expect a
return to VFR. Cannot rule out an isolated shower this afternoon
although chances are much too low to include given limited
moisture and weak dynamics. Models indicate potential for
stratus and fog beginning around 06Z Wednesday morning.
However, a 25 to 30 knot low level jet will promote mixing, so
expect mainly stratus development. Winds will pick up out of the
south after daybreak to around 5 to 10 knots.

Wednesday morning through Thursday in unsettled weather with
occasional showers and thunderstorms.


Records for the date...

February 28...AGS 86 set in 1962
              CAE 84 set in 2011

March 1.......AGS 85 set in 1997
              CAE 83 set in 1997




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