Area Forecast Discussion
Issued by NWS La Crosse, WI

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637
FXUS63 KARX 161127
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
527 AM CST Tue Jan 16 2018

.UPDATE...
Issued at 339 AM CST Tue Jan 16 2018

Quick update to trim the eastern portions of the Wind Chill
Advisory. Warmer air (in a relative sense) wrapping back westward
early this morning has kept wind chill readings well above
advisory criteria closer to the Mississippi River, and just don`t
see us hitting criteria through the morning. Areas farther west
toward the I-35 corridor will still ride the -20F criteria this
morning. In addition, watching clearing skies working south across
the area and have updated cloud trends to suggest more in the way
of sunshine initially this morning, especially the northeast
two-thirds of the area.

&&

.SHORT TERM...(Today through Wednesday Night)
Issued at 142 AM CST Tue Jan 16 2018

Water vapor loop early this morning showing elongated/sheared  mid-
level low extending from he Great Lakes back into the Central Plains
while the surface low was situated over Lower MI. Cyclonic
circulation around this system was still producing some patchy light
snow/flurries across our area but accumulating snow very much
diminished at this point in time. Otherwise, cloudy skies prevailing
across the area with temperatures as of 1 am in the single
digits/teens above zero east of the Mississippi River and single
digits below across southeast MN/northeast IA. Brisk northwest winds
on the backside of the low across southeast MN/northeast IA
producing bitter cold wind chills in the 20 to 30 below range. Plan
on a gradual/relative improvement in these wind chills today as
winds die down in slackening pressure gradient. As such, expiration
of the Wind Chill Advisory at noon today looks good. Otherwise, plan
on mostly cloudy skies this morning with a few flurries, then some
clearing this afternoon as high pressure builds in from the Plains.

High pressure ridge slides over the area tonight for partly cloudy
skies and fairly light winds. Overnight lows are expected to dip
into the single digits below zero with wind chills in the -10 to -20
range.

Quiet with moderating temperatures expected for Wednesday as warm
air advection sets in on the backside of the departing ridge of high
pressure. Plan on near normal highs in the lower/middle 20s with
lows Wednesday night in the teens above zero.

.LONG TERM...(Thursday through Monday)
Issued at 142 AM CST Tue Jan 16 2018

System passing through southern Canada Thursday is expected to
increase some mid-level cloudiness into areas mainly north of I-94.
Otherwise, warm air advection with this system should push highs
into the lower 30s.

Milder weather on tap for Friday into Saturday as well as mid-level
ridging passes through the Upper Mississippi River Valley region.
Highs Friday and Saturday expected to top off in the middle 30s to
the lower 40s.

Attention then turns to system impacting the area Sunday into
Monday. Whether the precipitation will be rain or snow is the big
question as the latest GFS/ECMWF showing differing tracks as it
bears down on the Upper Mississippi River Valley region. 16.00Z
ECMWF would be rain and even a small chance of thunderstorms while
the GFS would say all snow with possibly significant accumulations.
These details will obviously be ironed out with subsequent model
runs.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 527 AM CST Tue Jan 16 2018

Tricky cloud forecast through at least early afternoon, with some
clearing trying its best to work southwestward across Wisconsin,
and likely to bring a return to VFR conditions at LSE by 13Z or so
per current trends. However, we are seeing some additional
development farther west where winds are gradually shifting a
little more northerly, suggesting RST may hang onto MVFR ceilings
(and probably some flurries at times) through at least midday.
However, with high pressure arriving later today, do expect to see
the lower stratus dissipate for most if not all locations by
evening, with just some passing higher level clouds briefly into
the evening and overnight hours. Winds will remain from the
northwest 10-15 knots for most areas today, shifting southwesterly
later tonight.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Wind Chill Advisory until noon CST today for MNZ086-094.

IA...Wind Chill Advisory until noon CST today for IAZ008-009-018-019.

&&

$$

UPDATE...Lawrence
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...Lawrence



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