Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 080824

Area Forecast Discussion
National Weather Service Columbia SC
324 AM EST Thu Dec 8 2016

An approaching cold front will move through the forecast area
today. The pressure ridge behind the front will extend through
the area Saturday. The coldest air of the season so far will be
associated with this air mass. The ridge will be off the coast
Sunday and temperatures will begin to moderate.


Early morning analysis shows a cold front located from northern
Virginia southwestward through central Tennessee into northern
Mississippi. Water vapor imagery shows a positively tilted trough
across the midwest and upper ridge over the Caribbean with
southwesterly flow aloft over our area.

Low stratus ceiling returned quickly after sunset with
visibilities starting to drop again across the Upstate and
western Midlands with moisture trapped beneath the inversion with
dry air atop the inversion. A dense fog advisory may be needed
and will continue to monitor.

The cold front will push across the region today during the 16z-
18z time frame with precipitable water values rising to around
0.8-0.9 inches. However, little convergence along the front as it
pushes through and 850mb flow west to northwesterly with a
downsloping component should limit precipitation chances. Little
precipitation shown on hi-res models and SREF lends more
confidence to decision to continue with a dry forecast today. The
colder air mass will be lagging the front a bit and temperatures
today should warm into the upper 50s to lower 60s.

Cold, dry high pressure will build into the area overnight in the
wake of the passing cold front. A 20-25 knot low level jet may
help to keep the boundary layer mixed tonight preventing ideal
radiational cooling but cold advection will be strong enough to
drop temperatures into the upper 20s to lower 30s.


Fair and dry weather expected this period with strong Canadian
surface high pressure building over the region. This will be the
coldest air mass of the season as 850mb temperatures fall to -6C
to -7C and possible near record lows Friday night.

Despite plenty of sunshine on Friday continued cold advection
with northerly flow will limit temperatures across the forecast
area in the 40s, some 10-15 degrees colder than normal. Near
ideal radiational cooling expected Friday night under clear skies
with a very dry air mass should yield overnight lows Saturday
morning well into the 20s. There remains some question as to how
much wind may remain at the surface with the center of the high
just off to the northwest but if winds do go calm, near record
lows are not out of the question.

Saturday will be similar to Friday with mostly clear skies
expected as the surface high shifts overhead with minimal mixing
and temperatures remaining well below normal in the 40s to lower
50s. The surface ridge will shift offshore Saturday night
allowing a return onshore flow and some isentropic lift which may
support increasing clouds towards dawn on Sunday which will
impact lows Saturday night, keeping them warmer than Friday night
in the mid to upper 20s, but still below normal.


The extended forecast remains uncertain with below average
confidence due to continued differences in medium range model
guidance and considerable spread among the ensemble solutions.
Given the uncertainty will continue with a persistence forecast.

The GFS which had been showing a cold front pushing through the
region late Sunday into early Monday has now trended away from
that solution, now moving a weaker shortwave eastward across the
Ohio Valley into the Mid-Atlantic Sun/Mon but keeping the cold
front to our north and west. A deeper upper low moves across
southern Canada Tuesday with shortwave energy inducing
cyclogenesis over the Mississippi Valley and this low lifts
northeastward into the great lakes and a strong cold front cross
our area on Wednesday. The Canadian and ECMWF depict a deeper
initial trough on Sunday and push a front through the area Monday
afternoon with the second system developing on Tuesday and
pushing a strong cold front through on Wednesday similar to the

Will continue to carry chance pops Sun night and Monday with
diminishing pops Monday night and dry on Tuesday. Pops increase
again on Wednesday with the strong front crossing the region.
Temperatures during this period will start off Sunday below
normal then become above normal on Monday followed by near normal
temperatures Tue/Wed.


Satellite indicating widespread stratus/strato-cu across the area
with some patchy dense fog developing in the West
Midlands/Piedmont region. HRRR suggesting fog may develop
southeast resulting in visibility restrictions at the area
Terminals. Confidence moderately high that some fog may impact
terminals along with lower ceilings toward morning as stratus
build down develops. IFR and MVFR conditions will be the rule
during the overnight hours. Light wind expected through tonight
with northwest wind around 10 knots developing Thursday morning.
VFR conditions should return by around 15Z Thursday. A dry cold
front will move through the region early this afternoon with
decreasing clouds in the afternoon...a few gusts to 20 mph

Another cold front may bring precipitation and associated
restrictions Sunday night into Monday.




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