Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 180441

Area Forecast Discussion
National Weather Service Columbia SC
1141 PM EST Sun Feb 17 2019

Expect a wet pattern through the forecast period. A continued
SW upper flow, with a series of embedded upper disturbances and
resultant surface waves, combine with abundant atmospheric
moisture to provide good chances of rain at times.


Quick update to add a dense fog advisory for the central and
northern Midlands as the warm front moves northward. Previous
discussion follows.

Tonight, the edge of the wedge boundary will move northward into
the southern portion of the forecast area. Temperatures will
gradually warm overnight as the boundary moves northward and
southerly flow pushes warmer air into the area. Along with the
warmer air, increasing isentropic lift will bring increasing
chances of showers to the area with the highest chances
remaining over the western and northern Midlands where the
moisture and lift will be greatest. The coolest temperatures
tonight will occur this evening or around midnight with lows
around 40 to the north and around 50 to the south. Areas of fog
are likely with a shallow layer of cool, moist air near the
surface. Fog may be dense at times and a dense fog advisory may
be needed tonight.


On Monday, a surface cold front will be moving through the cwa
early in the day, with scattered showers occurring in advance
of the front. By the early afternoon, the front and its
associated rainfall, will be east of the forecast area, with
drying taking hold for the remainder of the afternoon hours.
Even with the passage of the cold front, temperatures on Monday
will be higher that previous days readings due to the surface
wedge being scoured out, breaks in the cloud cover, and westerly
winds bringing some slight downslope warming east of the
Appalachians through the day.

Dry conditions will continue into Monday night. Some clouds
should still be lingering around the area, and winds will not go
calm, so not ideal in regards to radiational cooling. However,
winds will turn more out of the north to northeast through the
night, helping to bring another weak wedge back into the area
from the north by Tuesday morning. Expecting overnight lows
mainly in the 40s Monday night.

On Tuesday into Tuesday night, the weak wedge pattern will
continue. Another shortwave west of the area will begin to bring
Gulf Moisture back northward. There remains some question as to
whether this moisture will be able to really push far enough
eastward from TN, northern AL, and Northern GA to bring much
rainfall to the cwa through Tuesday night. This is due to the
upper ridge that has been situated off the southeastern
coastline. If the ridge remains entrenched and rather strong,
precip may have a hard time pushing east, and may end up riding
around the ridge. This would keep the heavier rainfall closer to
the upstate of SC and into western/central NC. Can not rule out
some drizzle through the day though.  Temperatures on Tuesday
will be cooler once again in the wedge, with readings from the
upper 40s to lower 50s. Lows Tuesday night in the upper 30s
north to the lower 40s south.

Similar conditions expected to start off the day on Wednesday
due to the continued wedge at the surface. Very light rain/drizzle
possible. The leading edge of the wedge may begin to weaken
across the eastern and southern cwa through the day, allowing
temperatures to climb into the middle 60s in those locations.
Areas further north and west remain entrenched in the cooler
airmass, and thus will only see temperatures from the middle 40s
north to the middle 50s central. Scattered showers once again
will be possible Wednesday into Wednesday night.  By Wednesday
night it appears as if the wedge may finally be scoured out once
again as another front pushes towards the area.


Thursday will see the front push south before eventually
stalling out just south of the area. Still should see scattered
showers into the weekend north of the fluctuating boundary.
Temperatures in the longer term remain very tricky and difficult
to pin down due to the potential for additional cold air damming
to move back into the area at some point. For now have gone more
with a model blend for temperatures through the weekend, which
keeps the colder air off to the north of the area. This keeps
temperatures above normal into the weekend.


High confidence in LIFR restrictions overnight. Improving
conditions by 09z-12z. High confidence for VFR by mid to late
morning Monday.

Cold air damming wedge continues across the area with strong
surface based inversion present. Observations indicating LIFR
dominating across the region. Warm front at 23z appears to be
approaching east central Ga/CSRA. Visibilities are lowering
ahead of the front and expect this trend to continue through the
late evening. Dense fog possible at area terminals by 04z.
Another issue is the low level wind shear expected 04z-08z. As
cold front approaches the region from the northwest around 06z,
a 40-50kt low level southwest jet expected above the surface
based inversion across the region. This will result in Low Level
Wind Shear as surface winds will be around 5 knots southeast
veering to south. Cold front moves through the region 08z-10z
and expect improving conditions to develop in its wake. Gusty
west winds as front moves through. During the morning expect
MVFR or better conditions to develop after 12z with west-
northwest winds around 10 knots. High confidence of VFR after
16z Monday.

EXTENDED AVIATION OUTLOOK...Restrictions possible at times
Tuesday through Friday as a stalled frontal boundary and a
series of low pressure systems move through or near the region.


SC...Dense Fog Advisory until 3 AM EST Monday for SCZ015-016-


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