Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 130841
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
241 AM CST Sat Jan 13 2018

.SHORT TERM...(Today through Sunday Night)
Issued at 241 AM CST Sat Jan 13 2018

High Impact Weather Potential: Low wind chills remain this morning,
but with the bigger story remains accumulating snowfall Sunday
afternoon and evening. Some impact to travel is possible.

Big bubble, no trouble. At least that`s the case at the moment with
a 1045mb surface ridge centered over North Dakota but extending well
into our area. Plenty of clear skies in place (thicker clouds off to
the south) coupled with Arctic air entrenched has again led to temps
falling below zero for all areas early this morning, with just
enough of a remnant gradient for wind chill readings to push solidly
into advisory criteria (-20F or colder). Those colder wind chills
will linger through mid morning or so before "recovering" into the
single digits below zero by afternoon (yeah for progress!) but
today`s highs will be coldest of the recent new cold stretch as the
core of Arctic chill settles overhead while the surface ridge drifts
directly across the area this evening. As that feature departs late
tonight into Sunday morning, may see another round of advisory-level
wind chills in developing return flow west of the Mississippi River,
but will let this current advisory run its course before re-upping.

Bigger story is our next system arriving later Sunday into Sunday
evening as a series of shortwaves emanating from northwest Canada
help carve out a stronger trough across the region into Monday, with
persistent hints that feature may actually close off over Wisconsin
by Monday afternoon. Uptick in warm advection ascent ahead of the
lead shortwave should deliver increasing coverage of snow Sunday
afternoon and early evening, with a very deep dendritic growth
region from the surface up through 10kft per forecast soundings
strongly hinting at great ratios of 20-25 to 1, and perhaps even a
little higher in spots. Still not an overall high amount of moisture
available per source region of this system and it will take some
work to saturate an initially very dry column. However, still
envision a general 1-3 inch accumulation for many areas, though with
00Z guidance starting a slight downward trend in precip totals,
owing to initial forcing being used up for top-down saturation.
Fluffy nature of snow should make removal easy but still some
possible travel issues to wrap up the weekend. At the moment, don`t
envision any headlines being needed for this one, but will need to
watch some slight blowing snow potential by Sunday night west of the
Mississippi.

.LONG TERM...(Monday through Friday)
Issued at 241 AM CST Sat Jan 13 2018

Looking like a cold start to the work week but potentially a more
mild finish, at least by January standards. Initial upper pattern
remains dominated by upper troughing in place but finishes with a
return to a more Pacific-dominated flatter flow regime across much
of the CONUS. Beneath that upper trough Monday into Monday night,
will continue to have the potential for some light snow at times,
especially near/east of the Mississippi River with bouts of deeper
moisture rotating back through the region. Not looking for any
significant accumulation, but wouldn`t be surprised to see maybe a
fluffy inch for some areas given continued deeper dendritic growth
through the column.

Thereafter, not much to discuss for the remainder of the work week
with broad low level ridging working across the area into midweek
before better return flow gets underway by Thursday. That setup
should favor temps actually trending a little above normal by late
week (do I hear 32 degrees?) but will need to watch cloud potential
in typical fashion for such mid-winter warm-ups.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1146 PM CST Fri Jan 12 2018

VFR conditions are expected through the TAF period. High pressure
moves into the region tonight through Saturday providing mostly
clear skies. A few mid level clouds are possible at KRST
overnight with cloud bases around 10kft.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Wind Chill Advisory until 9 AM CST this morning for WIZ017-029-
     032>034-041>044-053>055.

MN...Wind Chill Advisory until 9 AM CST this morning for MNZ079-
     086>088-094>096.

IA...Wind Chill Advisory until 9 AM CST this morning for IAZ008>011-
     018-019-029-030.

&&

$$

SHORT TERM...Lawrence
LONG TERM...Lawrence
AVIATION...Wetenkamp


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