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Area forecast discussion
National Weather Service La Crosse WI
1209 PM CST Thu Dec 12 2019

Update...
issued at 1209 PM CST Thu Dec 12 2019

With snow quickly winding down across southeast Minnesota into
west central Wisconsin, allowed the Winter Weather Advisory to
expire for Wabasha, Buffalo, and Trempealeau counties. Amounts so
far have ranged from around an inch near I-90 to 4-5 inches over
parts of Taylor co in Wisconsin. Additional amounts north of I-94
will mainly be an inch or less. A few reports of freezing drizzle
have been received near the edge precip band. This could lead to
some slick spots on roads, including areas that saw little snow.

&&

Short term...(today through Friday night)
issued at 255 am CST Thu Dec 12 2019

GOES water vapor imagery showing very tightly wound up mid-level
positive vorticity center rotating eastward along the ND/South Dakota border.
This pv anomaly will continue to spin east-southeastward into the
area with associated surface low tracking out of eastern NE into
northern Iowa/southwest WI this morning -and then through east-central
WI by early this evening. Currently watching observations upstream
across Minnesota/ND ahead of the mid-level circulation -a lot of
visibilities of 1-2sm in snow mainly along and north of I-94. Some
ongoing light snow right now across north central WI in warm air
advection arm ahead of this wave. Expect upstream snow to spread in
and unfortunately pick up with fervor (possibly approaching 1 inch
per hour rates) in the advised area for the morning commute and rest
of morning hours. Latest short term/hires models locking in on
forcing producing around 4-6 inches across Clark/Taylor counties in
north central WI and 3-5 inches northeast of I-94. Decided to expand
Winter Weather Advisory southward a tier of counties based on this.
1-2 inches expected between the I-90/94 corridors with lesser
amounts across the rest of the area. Look for the snow to taper off
from west to east late this morning and through the afternoon. Will
also have to watch for the possibility of some light drizzle/
freezing drizzle as the snow exits with weak residual lift in
iceless stratus left behind. Otherwise, plan on highs today topping
off around 20 degrees across north central WI and upper 20s to mid
30s across the rest of the area.

A brief respite tonight as high pressure builds in. Overnight lows
are expected to bottom out in the teens to lower 20s under mostly
cloudy skies.

Attention then turns to an elongated trough of low pressure moving
east across the plains and into the area Friday. Could see around an
inch of snow accumulation from this. Plan on highs in the mid 20s to
mid 30s.

That trough of low pressure will slowly amble east through the area
Friday night. Will have to keep an eye out for a light wintry mix
potential (light snow and or drizzle/freezing drizzle) as model
soundings show a loss of ice in clouds. Overnight lows are expected
to drop into the teens lower 20s.

Long term...(saturday through wednesday)
issued at 255 am CST Thu Dec 12 2019

Colder modified Arctic air oozes into the area Saturday behind
departing trough of low pressure. Will still have a chance of some
light snow/snow grains as column cools enough for icing through the
stratus layer. Plan on highs in the teens and 20s.

Keeping an eye on low pressure moving northeast out of the Southern
Plains into the Ohio River valley Monday/Monday night. The European model (ecmwf)
would keep any precipitation south with it's track while the more
more northern tracking GFS would clip a good portion of our area
with some snow. Otherwise, below normal temperature trend continues
through Wednesday as mid-level trough/modified Arctic air slides
through the region. Look for highs only in the teens and 20s

&&

Aviation...(for the 18z tafs through 18z Friday afternoon)
issued at 1209 PM CST Thu Dec 12 2019

Snow is quickly winding down as a weak surface low passes to the
east. However, some flurries/drizzle may persist along with
IFR/MVFR ceilings this afternoon/evening with plenty of low-level
moisture lingering. Maintained MVFR ceilings through the remainder
of the period with low confidence in clearing given weak surface
flow/low-level moisture. Additional light snow is possible on
Friday, but given expected timing, have not mentioned in the taf
yet.

&&

Arx watches/warnings/advisories...
WI...Winter Weather Advisory until 3 PM CST this afternoon for wiz017-
029-034.

Minnesota...none.
Iowa...none.
&&

$$

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