Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 072013

Area Forecast Discussion
National Weather Service La Crosse WI
213 PM CST Thu Dec 7 2017

.SHORT TERM...(Tonight through Friday Night)
Issued at 213 PM CST Thu Dec 7 2017

Area remains under a deep/cold mid-level trough extending from
Hudson Bay Canada through WI into the central/southern Plains.
Pretty quiet/mostly sunny this afternoon with temperatures in the
teens/lower 20s.

Another weak embedded shortwave trough will drop into the area
tonight for an increase in clouds and a few flurries after midnight.
Look for the clouds and flurries to continue through Friday with
highs in the 20s/lower 30s.

Attention then turns to some minor snow accumulations for Friday
night as a more vigorous shortwave trough drops southeast across
the area. Looks like generally 1-2 inches along and east of the
Mississippi River with lesser amounts expected west. Most of this
snowfall is expected to be before midnight...tapering off quickly
after midnight. Winds are expected to pick up by late in the
evening/overnight as pressure gradient increases. This may lead to
some blowing around of the freshly fallen snow.

.LONG TERM...(Saturday through Thursday)
Issued at 213 PM CST Thu Dec 7 2017

Saturday looks quiet as high pressure builds into the region.
Otherwise, chilly with highs only in the teens to middle 20s.

Warm air advection overspreads the region Sunday ahead of a cold
front dropping south out of Canada. Not expecting any precipitation
as of now but will have to keep an eye on this as some sounding data
shows saturation through the column. Otherwise, mostly cloudy skies
will prevail with highs in the upper 20s to the upper 30s.

A chance of snow moves into the area Sunday night into Monday as
that aforementioned cold front sinks into the area with an upstream
mid-level shortwave trough interacting on the frontal gradient.
Potential exists for some minor snow accumulations with this

Intermittent light snow chances linger Tuesday through Thursday as
we remain locked in perturbed northwest flow aloft.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1150 AM CST Thu Dec 7 2017

VFR conditions are expected through the afternoon and evening
hours, with winds in the 7-12 kt range switching from the
northwest this afternoon to southwesterly this evening. Guidance
then suggests MVFR ceilings in the 1500 to 2500 ft agl layer
moving in at some point during the overnight hours. While the RAP
is the fastest (and somewhat of an outlier compared to other
models), it seems to have had the best handle on clouds this
morning, so have trended forecast toward this guidance, bringing
in the cloud deck at 6Z and 7Z for RST and LSE, respectively.
Should other guidance prove to be better, the deck would be moving
in somewhere in the 9-12Z time period. Also expect some flurries
with these clouds, but not anticipating any visibility
restrictions. Could see ceilings lifting a bit with daytime
heating on Friday, but not confident enough to bring either TAF
site back to VFR levels.




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