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000
FXUS62 KCAE 211110
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
610 AM EST Mon Jan 21 2019

.SYNOPSIS...
A cold and dry pressure ridge approaching from the west will
extend through the forecast area today, then move offshore
Tuesday. Moisture will begin to return Tuesday night and
Wednesday with some spotty light showers and increasing clouds.
A cold front will approach on Wednesday and move through
Wednesday night, bringing more showers. High pressure will move
in for Friday, with a reinforcing high behind a dry cold front
moving in on Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
The cold surface pressure ridge will approach from the west
today and be in the region tonight. There will be much less wind
today compared to yesterday with the ridge axis nearing the
area. Satellite trends support just high thin cloudiness at
times. We leaned toward the lower temperature guidance today
because of the cold air mass. Used the guidance consensus
tonight.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
Tuesday...the arctic air mass will slowly start to moderate as
the high pressure area moves to the outer banks and low level
southeasterly flow from off the Atlantic begins. Afternoon high
temps will still be several degrees below normal, with only the
southern part of the FA expected to crack 50.

Tuesday night...the low level return flow strengthens, bringing
enough low level moisture to produce clouds and some very light
precipitation in the form of light rain or drizzle.
Precipitation type looks to potentially be an issue in far
northern areas of the FA close to the Charlotte Metro. 00Z NAM
forecast soundings indicate a possible period of light freezing
drizzle, mainly between 06Z and 12Z, whereas 00Z GFS is too
warm. Normally I would tend to side with the NAM when it comes
to handling the slower erosion of the arctic wedge, but it has
been too aggressive with holding on to cold air in the couple of
systems we have had already this winter. Therefore, I am going
with a mix of ZR-/R- for northern Lancaster County Tuesday night
with no ice accumulation for now, hoping that future model runs
will clear up the issue a little bit. Min temps will not be as
cold given the cloud cover and gradual warming, with min temps
ranging from around freezing in the far north to around 40 in
the far south.

Wednesday...Skies will be generally cloudy, but significant warming
will occur as winds turn around to the south ahead of the next
low pressure area and associated cold front. There will still be
a chance of some light rain, but I expect the more significant
rain will hold off until Wednesday night. Temps will almost feel
tropical-like after Monday and Tuesday, with highs from around
60 in the far north to around 70 in the far south. Winds will be
increasing on Wednesday as well.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Rain will come in earnest Wednesday night and Thursday morning as
the cold front and associated low move into the region. A surge
in PWs to 1.5 inches and above, along with a very favorable jet
location providing significant diffluence aloft, support a
period of moderate to heavy rain. The models do have timing
differences, with the GFS running about 6 hours faster than the
ECMWF, so there will still likely need to be some future
adjustments in that regard, but I have high confidence the
entire FA will get wet.

An area of high pressure will move in behind the front for
Thursday afternoon and Thursday night, but the air mass will not
be of arctic origin, so expect more normal late-January temps. A
weak, dry cold front may move through on Friday with a
reinforcement of somewhat colder air.

High pressure should continue to dominate on Saturday, and after
a chilly start we should be up to normal temps in the 50s.
Another area of low pressure will be approaching from the west
on Sunday, but the models really begin to diverge at this point,
so I have just gone with a blend of everything for now.

&&

.AVIATION /11Z MONDAY THROUGH FRIDAY/...
We have high confidence of continued VFR conditions through the
24-hour TAF period.

Dry high pressure moving into the region will dominate. There
will be diminished wind with the ridge axis nearing the area.
Followed the GFS LAMP with wind north to northeast at 5 to 10
knots. Satellite trends support just periods of thin high
cloudiness at times. It should remain too dry for fog.

EXTENDED AVIATION OUTLOOK...MVFR or IFR cigs are expected to
return Tuesday night into Wednesday morning due to low clouds.
We may see a break for a little while Wednesday afternoon, but
low cigs/vsbys will likely return Wednesday night, maybe
stretching into Thursday morning, as a low pressure area and
cold front move through from the west. VFR conditions dominate
the later half of the week.

&&

.HYDROLOGY...
Rainfall totals ranged from 1 to 1.25 inches across the Upstate
and headwaters of the area rivers to .75 to 1 inch across much
of the Midlands and CSRA. This will produce rises on the area
rivers early this week. Some minor flooding is forecast along
the Congaree River south of Columbia as the water moves down the
Broad and Saluda River basins.

&&

.EQUIPMENT...
The Columbia, SC (KCAE) WSR-88D is out of service due to a
faulty voltage regulator. The part will be ordered but an
estimated time of arrival is unknown at this time.

&&

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

&&

$$
SYNOPSIS...99
NEAR TERM...99
SHORT TERM...99
LONG TERM...99
AVIATION...99
HYDROLOGY...99
EQUIPMENT...99