Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 100546

Area Forecast Discussion
National Weather Service La Crosse WI
1146 PM CST Sat Dec 9 2017

Issued at 843 PM CST Sat Dec 9 2017

Forecast updated to include light snow the rest of this evening
for locations mainly along and east of the Mississippi River. Western
into central Wisconsin has the best chance of seeing measurable
snow. Shortwave trough pushing through the area is driving an
area of very light snow over portions of eastern Minnesota into
northwest Wisconsin. This activity is just starting to make it
into Wabasha and Buffalo Counties. Have been seeing visibility
restrictions  in the snow over northwest Wisconsin so am
anticipating  some light accumulations as it moves through. Most
area will see at least flurries and some spots could measure a
1/10 to 2/10 inch of snowfall.


.SHORT TERM...(Tonight through Sunday Night)
Issued at 215 PM CST Sat Dec 9 2017

Forecast area remains in north-northwest flow aloft with the next
Canadian short-wave set to dive south across the region late tonight
into Sunday morning. Although the wave will provide some modest
lift, area soundings are rather dry, only showing a shallow 1 km
saturated layer near the surface. As a result, will maintain a dry
forecast through Sunday with the primary sensible weather impacts
being a surface wind shift to the northwest and mostly cloudy skies.

Although low stratocumulus this afternoon will gradually lift and
dissipate, additional mid-high level cloud cover will move in
overnight ahead of the above mentioned short-wave. These clouds will
keep temperatures from completely bottoming out with nighttime lows
generally in the teens. Temperatures Sunday will rise into the mid
20s to lower 30s.

Attention then turns to low pressure diving southeast out of
Saskatchewan Canada into northern MN Sunday night. Wing of warm air
advection/isentropic upglide will push across the area for outbreak
of light snow mainly east of the Mississippi River. Right now
looking like 1-2 inches of accumulation possible northeast of I-94
with lesser amounts to the southwest. In addition, soundings show
the potential for loss of cloud ice on the southwest flank of the
warm air advection overnight. Therefore, will have to watch for some
patchy freezing drizzle as there will be lift in the lingering
stratus layer.

.LONG TERM...(Monday through Saturday)
Issued at 215 PM CST Sat Dec 9 2017

Low pressure moves through the area on Monday for a continued chance
of some light snow along with the possibility of some patch freezing
drizzle in the morning. Bulk of the precipitation looks to push east
of the area by afternoon as the low pulls into the Great Lakes
Region, however, could still see some lingering flurries or drizzle
as there will be plenty of lingering cloud around with weak lift.
Otherwise, northwest winds will also be on the increase with gusts
by late morning through the afternoon in the 20-30 mph range.
Temperatures are expected to top off in the upper 20s to upper 30s.

Quiet period sets up Monday night through Tuesday night with no
embedded troughs noted in prevalent northwest flow aloft. It will be
cold though with highs Tuesday only in the teens/lower 20s. Expect
lows Tuesday night in the single digits above zero across central WI
to the lower teens west of the Mississippi River.

Wednesday through Saturday will see several embedded shortwave
troughs rotating through in northwest flow aloft, yielding small-end
light snow chances through this period. Temperatures look to be at
or a couple degrees above normal.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1146 PM CST Sat Dec 9 2017

MVFR stratus is expected to overspread the TAF sites in the 13-14Z
timeframe Sunday morning. The stratus then looks to linger over
the region for much of the TAF period, but there may be a few
breaks or improvements to VFR briefly. Plan on cloud bases in the
2-3kft range.




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