Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 081725

Area Forecast Discussion
National Weather Service La Crosse WI
1125 AM CST Thu Dec 8 2016

.SHORT TERM...(Today and tonight)
Issued at 330 AM CST Thu Dec 8 2016

Clouds along with some light snow and flurries at times is
expected again today into tonight as the upper low continues to
pull away but cyclonic flow aloft persists. Some very light fluffy
accumulations are possible under any more persistent snow showers,
especially north of I-90. Winds will be gusty again from the
northwest, which could lead to a bit of drifting snow in any areas
that receive light accumulations. The warmest highs today will be
north of I-94 where thermal profiles are just a bit warmer.

.LONG TERM...(Friday through Wednesday)
Issued at 330 AM CST Thu Dec 8 2016

A very wintry period certainly looks to be in store for the Upper
Midwest over the weekend into next week, but exactly how this time
period unfolds is still uncertain as models have not shown much
consistency over the past few days.

After quiet weather under the influence of high pressure on Friday,
the upper air pattern becomes zonal to start the weekend. Within
the fast zonal flow, models have had a tough time resolving
embedded disturbances. The 08.00Z GFS/NAM show a stronger wave
riding the mid-level baroclinic zone Saturday afternoon/evening
eastward from the northern plains compared with the ECMWF/GEM.
Stronger vertical circulations associated with the more intense
wave/warm advection denoted by the GFS/NAM would support greater
snowfall potential than the ECMWF/GEM. Current forecast maintains
continuity with highest snow chances Sat afternoon/evening along
and south of I-90, with several inches of snow possible.

In addition, the ECMWF/GEM and even the GFS to some extent have
shown a somewhat more amplified trailing wave behind the lead
system for later Sunday/Monday with a surface cyclone lifting
northeastward out of the Mid-Mississippi Valley. Depending on the
track of this wave, snow would be possible into early next week
over some parts of the area.

With so much variability among model runs and overall poor run-
to-run consistency with track, intensity, and timing, confidence
in snowfall details remains on the lower side through the weekend.
However, with the energetic zonal to southwesterly flow through
early next week, this is certainly a time period to continue to
watch for accumulating snowfall potential.

After these systems pass by, cold temps will again be the story
heading towards the middle of next week. The GFS/ECMWF bring the
Arctic front through around Tuesday, possibly with some light snow
with the strong frontal forcing. How cold it gets behind the front
will depend to some extent on how much snow cover is on the ground
at this time. Global models have gone back and forth on the
amplitude of the upper trough which may impact forecast details,
but confidence is high that we will see another surge of cold
temps, likely colder than this week`s cold, with some subzero
temps possible and bitterly cold wind chills.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1125 AM CST Thu Dec 8 2016

MVFR ceilings will persist through the period from 2000 to 3000
ft agl at KLSE and 1000 to 2000 ft agl at KRST. Scattered snow
showers/flurries will continue through at least this afternoon and
possibly into the evening/overnight, but overall impacts to
aviation operations will be minimal outside of a brief reduction
in visibility between 3 and 5SM. Northwest winds will continue,
gusting at times to around 25 kts at KRST this afternoon, before
subsiding a bit this evening and overnight.




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