Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 041126

Area Forecast Discussion
National Weather Service Columbia SC
626 AM EST Sun Dec 4 2016

A low pressure system in the Gulf of Mexico will move northeast
through Tuesday...bringing periods of widespread rainfall to the
region. A cold front will cross the area Tuesday afternoon with
dry high pressure briefly building across the area for mid-week.
A strong cold front crossing the region Thursday will usher in
unseasonably cold conditions for the end of the week.


Weak upper level ridging over the eastern states will move
offshore tonight as a large upper level low over Mexico tracks
eastward into Texas overnight. Wedge conditions developing across
the region with surface high pressure over the Mid-Atlantic region
and a storm system over the northern Gulf of Mexico. Models
indicate a strong 850 mb jet 40-50 knot bringing abundant low
level moisture into the region late this afternoon into tonight.

Spotty light rain will continue this morning. Increasing isentropic
lift will bring widespread rainfall to the area this afternoon and
tonight. We kept categorical pops for today and tonight.
Should see little change in temperature. Highs today will range
from the mid 40s north to lower 50s south. Lows tonight will
range between 40 and 50 degrees.


The wedge pattern should hold across the area Monday. However...
we should see a relative lull in rainfall Monday as a lead short
wave moves east of the Midlands and isentropic lift weakens.
Models have been consistent indicating high temperatures in the
mid 50s to lower 60s on Monday. Given CAD setup have continued to
go below guidance for highs ranging through the 50s.

The next surge of moisture advection/isentropic lift will affect
the area late in the day Monday into into Tuesday as a 50-60 knot
850 mb jet crosses the region. Kept categorical pops for Monday
night into Tuesday morning. Storm total rainfall should be in the
2 to 3 inch range.

A warm front may move into the forecast area Tuesday but this is
questionable because the cool wedge may linger. The models often
erode the cooler/wedge conditions too quickly. Depending on where
the boundary sets up...isolated storms are possible Tuesday as the
upper trough and surface cold front crosses the region. Severe
thunderstorms could possibly occur if the warm front gets into the
forecast area and surface-based instability develops.
Convection should diminish Tuesday afternoon. Went near guidance
consensus for high ranging from the mid 50s north to lower 70s


The medium-range models show the cold front off the coast Tuesday
night with dry high pressure building in through Wednesday night.
Another cold front looks to cross the region in the Thursday. The
GFS is a little drier in the way of precipitation while the ECMWF
continues to be slower and wetter.Seasonable temperatures are
forecast Wednesday and Thursday.

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 funneled into the region and daytime highs Friday
and Saturday will only be in the 40s. However, it will warm back
into the 50s to lower 60s on Sunday as the upper level flow shifts
to the southwest. There is also reasonable agreement between the 00Z
GFS and ECMWF models showing another frontal system that could bring
rain at some point Sunday or Sunday night.


Surface high pressure will continue to ridge into the forecast
area from the north which will facilitate east-northeast winds.
Dry low-level air associated with this ridge has delayed lowering
ceilings. However, a warm front south of the forecast area and
well ahead of low pressure in the western Gulf of Mexico will continue
to advect moisture into the region. Currently, light rain showers
are moving through northern portions of the CWA, but heavier rain
will move over the TAF sites this afternoon and through the night.
This will cause MVFR and possibly IFR conditions through Monday

EXTENDED AVIATION OUTLOOK...Expect widespread IFR conditions
associated with a warm front through Tuesday. Drier conditions are
expected on Wednesday, but then a cold front could bring some more
light rain on Thursday, as well as west winds.




LONG TERM...10/82
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