Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 142037
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
237 PM CST Sun Jan 14 2018

.SHORT TERM...(This afternoon through Monday)
Issued at 237 PM CST Sun Jan 14 2018

Watching a pesky band of light warm advective snow/flurries lifting
northeastward this afternoon across the forecast area. For the most
part, this will result in a trace to possibly a light dusting.
Higher impact snow is still upstream across central and northern MN,
but will move into the area late this afternoon and evening as a
strong clipper system closes off and drops south across MN.

Cold temperatures this evening through tomorrow result in a deep
dendritic growth zone (at times reaching 10 kft). With models
showing roughly 5-6 microbars per second of lift within the DGZ,
expect dendrites and higher snow ratios. Just how high is still a
bit of a question, but most guidance is near 20:1. At the same
time, QPF from GEFS/SREF plumes are clustered around 0.20 to 0.25
inches of liquid. This should result in snow amounts through
Monday in the 2 to 6 inch range. Higher amounts (3-6 inches) are
expected east of the Mississippi River as an inverted surface
trough pivots across western/central Wisconsin on Monday, resulting
in periods of additional light snow. Will add Buffalo and
Trempealeau Counties to the current Winter Weather Advisory based
on snow amounts.

Also watching winds and the potential for blowing/drifting snow. A
cold front moves into the forecast area after midnight, resulting
in increasing northwest wind. With roughly 25 to 30 kts in the
boundary layer, could see surface gusts around 30 mph for areas
west of the Mississippi River, especially on Monday. With less
expected snowfall for these areas, will include patchy blowing and
drifting snow, but will need to monitor the situation for expanded
coverage and possible Winter Weather Advisory headlines.

The above mentioned winds and cold air temperatures will result
in bitter cold wind chills tonight through Monday for areas west
of the Mississippi River. A Wind Chill Advisory will continue with
wind chills in the 20 to 35 below range. After collaboration with
neighboring offices, also added the counties between the Mississippi
River and the current Wind Chill Advisory.

.LONG TERM...(Monday night through Sunday)
Issued at 237 PM CST Sun Jan 14 2018

Light snow will finally diminish and move east Monday night,
although continued northwest breezes and air temperatures dropping
into the single digits below zero will result in bitter cold wind
chills for areas west of the Mississippi River through Tuesday
morning.

Tuesday through Friday look quiet as surface high pressure
dominates the regional weather pattern. Increasing ridging aloft
will allow temperatures in the single digits and teens above zero
on Tuesday to rise into the lower to mid 30s by Friday.

Next weekend, flow aloft shifts to the southwest allowing for a
larger system to lift northeastward somewhere across the Upper
Midwest. Run to run consistency has been poor, so details are far
from certain, but something to watch closely over the coming week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1158 AM CST Sun Jan 14 2018

Generally VFR conditions expected through the early afternoon
hours, other than possibly some brief snowfall with MVFR
visibility/ceilings at RST for the very beginning of the period.
Attention then turns to timing of a more prolonged period of MVFR
ceilings and snow leading to IFR visibilities for both sites.
Currently thinking onset of snow will be late afternoon (22/23Z
for RST/LSE, respectively), with some brief periods of LIFR
visibilities and IFR ceilings through the evening, but may need to
refine timing a bit this afternoon. Snow will come to an end for
RST by the early morning hours on Monday, but light snow is
expected to linger through much of Monday at LSE. Winds will
switch from southerly to northwesterly following the heaviest
snow, with gusts to around 25 kts possibly leading to some blowing
snow for RST Monday morning.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 6 PM this evening to midnight CST
     Monday night for WIZ017-029-032>034-041>044-053>055-061.

MN...Wind Chill Advisory from 3 AM Monday to noon CST Tuesday for
     MNZ079-086>088-094>096.

IA...Wind Chill Advisory from 3 AM Monday to noon CST Tuesday for
     IAZ008>011-018-019-029-030.

&&

$$

SHORT TERM...Rogers
LONG TERM...Rogers
AVIATION...CA



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