Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 181701

Area Forecast Discussion
National Weather Service La Crosse WI
1101 AM CST Thu Jan 18 2018

.SHORT TERM...(Today through Friday Night)
Issued at 334 AM CST Thu Jan 18 2018

Area early this morning was between high pressure centered over the
Southern Mississippi River valley and a rather potent mid-level low
rotating eastward across southwest Ontario. Resulting southwest flow
was bringing milder air into the region with temperatures as of 3 am
in the teens above zero.

For today, the wave across southern Canada will bring a few warm air
advection mid/high clouds across the area, mainly along/north of I-
94 today. Otherwise, milder temperatures on tap for today with highs
expected to top off well into the 30s.

Another wave of low pressure will track across southern Canada
tonight through Friday night, drawing in even milder air into our
region along with a few clouds from time to time. Plan on lows
tonight and Friday night in the upper teens to middle 20s with highs
Friday in the upper 30s to lower 40s.

.LONG TERM...(Saturday through Wednesday)
Issued at 334 AM CST Thu Jan 18 2018

Increasing clouds will be seen Saturday as a cold front sinks slowly
south out of Canada into northern MN/WI. Otherwise, relatively mild
temperatures will continue with highs in the upper 30s to lower 40s.

Attention then turns to incoming storm system which will impact our
region Saturday night through Monday night. Models in good agreement
on influx of lower level moisture into the area Saturday night in
increasing southerly flow ahead of surface cyclogenesis over the
Central Plains. Model soundings show this moisture being realized as
stratus and possible freezing drizzle/rain given subfreezing surface

Latest 18.00z ECMWF/GFS both showing a warmer/wintry mix scenario
for our area Sunday into Monday as strong low pressure tracks
northeast across the region. A gradual transition to some snow in
the colder deformation area on the backside of the departing low is
then being depicted by the models by Monday night. This storm system
is still in its infancy in the Gulf of Alaska and much could change.
Better data sampling for model should take place Friday as the
system makes landfall over CA. Will continue to monitor the
evolution of this system and potential impacts on our region.

Cyclonic flow on the backside of the departing low will bring colder
air in across the region and linger cloud cover Tuesday into


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1101 AM CST Thu Jan 18 2018

VFR conditions are expected through the period. Ridging aloft will
be moving into the region but gradually weakening overnight into
Friday. With this ridging moving in, only expecting some
occasional high level clouds to be over the area. At the surface,
high pressure over the southeast part of the country will maintain
a south to southwest flow over the region with speeds around 10




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