Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 040239

Area Forecast Discussion
National Weather Service Columbia SC
939 PM EST Sat Dec 3 2016

Dry conditions will persist through this evening with surface
ridging across the region. A low pressure system in the western
Gulf Coast Region Sunday will move northeastward and into the Ohio
River Valley Tuesday. The associated warm front will likely remain
south of the forecast area through Monday then lift north near or
into the forecast area Tuesday ahead of a cold front. The cold
front will likely be off the coast Tuesday night. Another cold front
will bring unseasonably cold conditions for next weekend.


Surface high pressure will continue to ridge into the forecast
area through tonight. Satellite trends indicate mid and high
cloudiness streaming into the forecast area well ahead of the
southern stream system over the southwest part of the nation. The
moisture will continue to increase tonight. Radar trends suggest
light rain become more widespread in north Georgia...moving toward
Upstate SC. Low levels remain dry at the moment. HRRR and rap
suggest rain will move into the Piedmont and possibly the west
Midlands/CSRA earlier than Mos guidance suggests. Raised pops in
the west through the overnight into tomorrow morning as isentropic
lift/moisture flux increases. Rainfall amounts will be quite light
through at least 09z due to dry low levels. Cloudiness will help
hold up temperatures tonight. The temperature guidance was


The models indicate a surface wedge pattern along with increasing
isentropic lift developing Sunday and continuing into Monday
night. At the surface...high pressure will reside along the mid
Atlantic coast Sunday providing a northeast low-level wind flow. A
system will move across the Great Lakes Sunday night and
additional high pressure will build in across the Mid Atlantic/New
England region for Monday into early Tuesday. An initial
shortwave trough will move east across the country on Sunday
tapping Gulf of Mexico moisture as it tracks eastward and bring
rain to the region by late Sunday. A more significant closed upper
low over northwest Mexico will eject eastward into the southern
plains and western Gulf Coast region by late Monday and cross the
region on Tuesday keeping rain chances high over the area.

Have indicted likely to categorical pops Sunday afternoon into
Tuesday morning. Have kept maximum temperatures below the
guidance for both Sunday and the upper 40s to mid
50s...because of wedge conditions. Used the local wedge equation
and blended it with guidance for temperatures. Should see little
diurnal cooling...with lows in the lower 40s to lower 50s.

The GFS...NAM and ECMWF hold the warm front south of the forecast
area through Monday night. The 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.


The medium-range models show the cold front off the coast Tuesday
night with dry weather through Wednesday night. Another cold front
looks to cross the region in the Thursday/Friday time frame. Both
the GFS/ECMWF sweep the front through on Thursday. The GFS is a
little drier in the way of precipitation while the ECMWF
continues to be slower and wetter.

Seasonable temperatures Wednesday and Thursday are forecast to
cool dramatically for the end of next week as much colder air
pours into the eastern conus.


Surface high pressure will continue to ridge into the forecast
area from the north through the TAF period. A warm front will
develop south of the forecast area well ahead of low pressure in
the western Gulf of Mexico. Cloudiness will be on the increase
during the TAF period but the initial dryness associated with the
surface ridging should help hold up ceilings. Latest radar
composite showing light showers moving into the western Midlands
this evening. Patchy light rain possible at all TAF sites during
the overnight. The GFS and NAM MOS and SREF guidance were
consistent will IFR or MVFR ceilings holding off until after 12z.
The MOS indicated light northeast wind. Expect periods of light
rain and possible MVFR fog across the area and during the
afternoon on Sunday.

EXTENDED AVIATION OUTLOOK...Expect widespread IFR conditions
associated with a warm front through Tuesday.




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