West Columbia, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

608
FXUS62 KCAE 220919
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
419 AM EST Sun Dec 22 2024

.SYNOPSIS...
Strong high pressure sliding to our north brings continued chilly
conditions into Monday. Both daytime highs and overnight lows
are expected to be below normal. Rain chances increase as a weak
coastal low develops early Tuesday. More seasonal temperatures
follow, with increasing chances for rain as an active pattern
moves into the area.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Message(s):

- Today is the coldest day of the week with subfreezing overnight
lows expected tonight.

Upper trough will move offshore today while the surface high advects
from the Great Lakes eastward over New England. Deep layer dry air
will continue over the forecast area, with satellite estimated PWATs
currently around 0.25". Temperatures valid 22/09z were generally in
the low to mid 30s, but continued cold advection this morning will
bring lows into the mid to upper 20s for many locations.

Cold and dry air will be well established over the region today as
the polar surface high pressure extends down the east coast. Daytime
temperatures will peak 8-12 degrees below normal this afternoon
(highs in the 40s) under clear skies. Tonight remains somewhat of a
concern as overnight lows are likely to fall into the low 20s along
the SC/NC border with mid 20s elsewhere through the Midlands and
CSRA. A few outlying or sheltered areas could dip into the upper
teens. The latest LREF probabilities for apparent temperatures 15
degrees or less tomorrow continues to trend downward from 24 hours
ago, with only about 10%-15% chances. The same probabilities
from the HREF peak at about 20%. Therefore, a Cold Weather
Advisory does not appear to be needed. That said, there will
still be impacts with these low temperatures, and appropriate
precautions should be taken.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Key Message(s):

- Cold start Monday with below average temps continuing into Tuesday.

- Rain overnight into Tuesday morning, with a very slight chance
  of some freezing rain.

The strong high surface pressure center to our north will continue
to dominant the pattern through Monday with well below average temps
and very dry air locked in place. Sustaining cold dry advection with
steady northeast winds will keep high temps in the 40`s again Monday
afternoon and drop surface dew points down into the teens. Things
start to get more interesting as we get into late Monday as 500mb
flow starts to flatten out as a subtle shortwave pushes in from the
west, eventually become southwesterly aloft by Monday evening. This
shortwave will interact with the sharp thermo gradient off the
Atlantic coast and quickly help develop some surface cyclogenesis by
roughly 00z Tuesday; all guidance is consistent with some sort of
coastal low development, both hi-res and global. 700-850mb onshore
circulation will consequently develop and drive WAA aloft. PWAT`s
will rapidly increase with this moisture flux aloft, increasing from
roughly 0.25" at 00z, up to 0.75" by 12z Tuesday. Strong WAA aloft
will push 850-700mb temps to 5-10 C. Isentropically driven showers
are then expected to develop within this WAA plume and push into
coastal SC, possibly into the Midlands and this is where guidance
starts to diverge. There is basically two camps in guidance: the
Canadian, its ensemble, and the much of the hi-res vs the GEFS and
EC suites. The Canadian and hi-res solutions drive a much larger
moisture field and showers into the Midlands, along with drier low
levels. This would yield a stronger wet bulbing solution and
therefore elevates the chance for some freezing rain across the
northern Midlands. The other camp is either weaker with shower
activity as the surface low shifts further east or a bit warmer-
moister ahead of any precip, so wet bulb potential is lower.
However, even in the colder wet bulb solution, the very strong warm
nose aloft would yield quite warm rain and would require more
than just borderline temps to result in freezing rain.

Overall, this is a bit of an atypical setup from a
climatological standpoint for a freezing rain threat with
residual cold air in place and sufficient moisture source, but
coming from the Atlantic as opposed to southern slider low
pressure. As expected, there is a typical, high amount of
uncertainty across guidance currently, but hopefully the 12z
suite will show its hand as to whether the freezing threat will
increase. Regardless, the potential ceiling for this event is
relatively low with a reasonable worst case scenario of a few
hours of very light borderline freezing rain overnight Monday
into Tuesday morning.


&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Key Message(s):

- Slow warm up expected through the remainder of the week.

The strong surface high pressure blocking across the NE CONUS will
remain the key feature of the long term, but a transition to a more
progressive flow aloft will steadily moderate the airmass into the
weekend. Short lived ridging Wednesday will give way to a
progressive shortwave Thursday, bringing some rain chances across
the area. The surface high pressure to the northeast will continue
NE flow into the area, with relatively dry air lingering. Building
heights aloft are expected as we get late in the week and weekend,
and this will help slowly warm temps up despite the surface ridging
lee of the Appalachians. NAEFS highlights this entire period pretty
well, with the well below average temps and heights steadily
increasing throughout the week. Longer range ensembles continue
to show a pattern shift towards deep eastern CONUS ridging for
the last few days of December and potentially well above
average temps and rain chances.


&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
High confidence VFR conditions expected through the TAF period.

SKC. A dry air mass and elevated winds should prevent any
fog/stratus concerns this morning. Winds will be from the
northeast around 4 to 7 knots most of the night, then increase
slightly to 6 to 10 knots by mid morning through the afternoon
hours. Light and variable winds are expected tonight into Monday
morning.

EXTENDED AVIATION OUTLOOK...There is potential for a few rain
showers and associated restrictions Monday night through the end of
the week.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...None.
GA...None.

&&

$$