Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 230440

Area Forecast Discussion
National Weather Service La Crosse WI
1140 PM CDT Thu Mar 22 2018

.SHORT TERM...(Tonight through Friday Night)
Issued at 249 PM CDT Thu Mar 22 2018

Dry today through Friday, then snow moves in (mainly west of the
Mississippi River) Friday night. Winter Storm Watch Friday evening
through Saturday morning for southeast MN/northeast IA/far southwest

Ridge of high pressure was providing sunny skies across the area
with temperatures as of 2 pm in the upper 30s to the middle 40s.
Clear skies will be seen tonight east of the Mississippi River while
some increase in cirrus cloud will likely be noted west of the river
after midnight. Light winds and mostly clear skies will lead to some
chilly overnight lows with readings dipping into the teens along and
northeast of I-94, and 20s elsewhere across the area.

Friday will see increasing/thickening cloud cover from southwest to
northeast through the day in advance of mid-level trough and surface
low pressure pushing out of the Central Rockies into the Plains. Any
precipitation chances should hold off through the majority of the
afternoon with maybe some light rain moving in west of the
Mississippi toward evening. Otherwise, plan on highs in the 40s.

Rain or a rain/snow mix is expected to quickly fill in across
southeast MN/northeast IA Friday as nose of higher precipitable
water pushes in ahead of approaching mid-level trough from the
Northern Plains and surface low over the Central Plains. Better 850-
500mb frontogenetic forcing/deep vertical motions kick in full force
in the 03-09z time frame. This is expected to produce some heavy
snow fall then for portions of southeast MN/northeast IA. Dry push
of air from the northeast will try to fight this forcing, setting up
what looks to be a pretty sharp gradient of very light snow to heavy
snow fall. Based on this, would like to keep the current Winter
Storm Watch going and wait to see where exactly this gradient for
heavier snowfall sets up per 23.00Z. Will leave this to the
overnight shift to assess and adjust headlines as needed. Right now,
it appears there is growing consensus for a band of 4-8 inches to
set up through Saturday morning with the heaviest snowfall axis from
Austin MN through Oelwein and Strawberry point IA. Again will let the
overnight shift assess the 23.00Z models to see if there is any
shift in this heavier snow axis.

.LONG TERM...(Saturday through Thursday)
Issued at 249 PM CDT Thu Mar 22 2018

Snow or a snow/rain mix will be tapering off Saturday, pushing
southeast out of the area by afternoon as the mid-level trough and
surface low head for the Ohio River Valley and high pressure builds
in from Canada.

The rest of the weekend looking rather nice as a ridge of high
pressure builds into the region. Plan on highs Sunday in the upper
30s across portions of southeast MN/northeast IA where fresh snow
cover is expected, and in the upper 30s to middle 40s east of the

A mid-level trough and surface cold front ooze into the area later
Monday into Tuesday for a chance of daytime rain and rain/snow mix
at night as temperatures cool. Look for highs in the 40s to
lower 50s with lows in the 30s.

Mid-level trough sets up across the Central CONUS Wednesday into
Thursday. Wednesday looks dry but there will be a chance of rain
Thursday south of I-90 as low pressure passes through IL. Models
producing highs in the middle 40s to middle 50s but these may be
trending down a tad with colder air aloft filtering in.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1141 PM CDT Thu Mar 22 2018

VFR conditions will continue through Friday afternoon. Conditions
will then lower to MVFR at KRST Friday evening with the potential
for IFR to LIFR conditions around and after 06Z. A storm system
moves into the region Friday into Friday night bringing some snow
to the region along with increasing easterly winds. Snow is
likely at KRST mainly after 06Z and the snow may be heavy at
times. Plan on ceilings lowering to around 2500 ft by 4 Z with a
rain snow mix switching over to all snow by 06Z and thats when
LIFR conditions may develop. Most if not all of the snow will stay
west of KLSE with mainly VFR conditions expected. Brief MVFR
conditions are possible if the snow band edges a little further
east. Main impacts from snow will be west of the Mississippi
River. Winds may gust to 35 kts at times at KRST Friday night.


WI...Winter Storm Watch from Friday evening through Saturday morning
     for WIZ054-061.

MN...Winter Storm Watch from Friday evening through Saturday morning
     for MNZ079-086>088-094>096.

IA...Winter Storm Watch from Friday evening through Saturday morning
     for IAZ008>011-018-019-029-030.



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