Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 021817

Area Forecast Discussion
National Weather Service Columbia SC
117 PM EST Fri Dec 2 2016

Dry conditions will persist through Saturday associated with
ridging. A low pressure system will track from the western Gulf
Coast Region northeastward into the Ohio River Valley early next
week. The associated warm front will likely remain south of the
forecast area through Monday. The warm front may lift north
and into the forecast area Tuesday ahead of a cold front.
The cold front will likely be off the coast late Tuesday.


Surface high pressure over the deep south will continue to ridge
into the area. Light N/NW surface winds currently observed will
become increasingly westerly as a lee-side trough develops this
afternoon. Near zonal upper flow and dry air will hold clear skies
across the region today. NW 850 mb winds indicate downslope flow
over the area which may lead to warmer afternoon temperatures than
guidance suggests. Afternoon highs are expected to be near normal
in the upper 50s to lower 60s.

Models have shown more cloud cover in recent runs, particularly
early Saturday morning. This agrees with current water vapor
imagery showing upper level moisture moving into the Deep South.
This would limit radiational cooling, at least for the later
portion of the night. Therefore favored the warmer temperature
guidance. Additionally a 20 to 25 kt LLJ may promote low level
mixing. Lows will generally be in the mid to upper 30s but depending
on the location/thickness of cloud cover could be near freezing
in some areas.


Dry weather will continue through Saturday night with surface
high pressure ridging into the area. Upper-level moisture will
advect into the region Saturday and Saturday night ahead of a
southern stream system over the southwestern part of the country.
The models indicate significant isentropic lift developing Sunday.
Leaned toward the higher pops Sunday based on the fast southern
stream flow. Forecasted pops becoming likely during the
afternoon. Followed the guidance consensus for the temperature
forecast Saturday and Saturday night. The increased clouds will
help hold up temperatures because of diminished net radiational
cooling Saturday night and it should not be a cool as the previous
night. Leaned toward the lower maximum temperature guidance Sunday
because of a cool start and expected cloudiness.


The GFS and ECMWF keep the warm front south of the forecast area
through Monday. Isentropic lift supports high pops. The high
temperature guidance is likely too high because of a wedge
pattern. The warm front may move into the forecast area Tuesday
but this is questionable because the cool wedge may linger.
The GFS and ECMWF have been consistent depicting a 50-knot h85
jet. The combination of the jet and cooling associated with the
h5 trough may help support thunderstorms and we have included
isolated storms in the forecast. Severe thunderstorms could
possibly occur if the warm front gets into the forecast area and
surface-based instability develops. The GFS and ECMWF have not
been consistent with a frontal system Thursday with the ECMWF
showing more moisture. Used an average for the pop forecast.


VFR conditions likely through the 24 hour TAF period.

Dry high pressure will continue to build into the region. Winds
will generally be out of the N/NW but may be light and variable
for many sites this afternoon. Wind direction will become
increasingly westerly through the afternoon as a lee-side trough
develops. Expect light and variable winds overnight with the
exception of DNL which may keep winds up overnight due to a 20 to
25 kt LLJ. Skies will be clear through the day with a few high
clouds moving over the area tonight and early Saturday. Fog is not

The inversion will break around 15z Saturday with NE winds around
5 kts. Scattered to broken high clouds will be present as upper
level moisture moves across the region.

EXTENDED AVIATION OUTLOOK...A system will bring precipitation and
periods of associated restrictions Sunday through Tuesday.




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