Area Forecast Discussion
Issued by NWS La Crosse, WI

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712
FXUS63 KARX 091735
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1135 AM CST Sat Dec 9 2017

.SHORT TERM...(Today and Tonight)
Issued at 303 AM CST Sat Dec 9 2017

At 3 AM, a 1004 mb surface low was located near Milwaukee.  Cyclonic
flow associated with this low kept skies mostly cloudy and produced
scattered flurries and light snow across the Upper Mississippi River
Valley.  Temperatures early this morning were mainly in the 20s.

The 09.00z models are is good agreement that the cyclonic flow will
persist through mid to late morning.  In addition, there will be
some small CAPES.  This will result in a continuation of some
flurries and light snow.  Little, if any, snow accumulations are
anticipated.

For this afternoon, the 925 mb ridge axis does not slide through the
area until late afternoon.  Due to this, increased the clouds.  As
the low clouds will be departing mid clouds will move into the
region ahead of another short wave trough.  These clouds will
persist through tonight.

While there will be some lift ahead of the short wave trough late
tonight, the moisture looks too shallow to produce any
precipitation.

.LONG TERM...(Sunday through Friday)
Issued at 303 AM CST Sat Dec 9 2017

Main focus through the later forecast periods remains various waves
dropping toward the area within continued broad upper troughing
remaining across the region. There are some hints we may start to
relax this deeper upper troughing pattern of late sometime into late
next week and beyond, perhaps offering some hope for a bit more
active weather regime locally, but plenty of time to watch those
trends unfold over the coming days. In the meantime, all eyes will
be on Sunday night with our next stronger shortwave dropping out of
Saskatchewan down into our neck of the woods, with actually
increasing consensus among guidance that this feature may bring a
period of additional accumulating snow for parts of the area. Rather
robust warm advection response aloft is noted with this wave over
the past few days of guidance runs, with lift maximized along/east
of the Mississippi River. However, said warming also hints that we
may deal with a period of reduced ice production through the cloud
layer, especially after midnight. All told, per current trends, can
envision a quick 1-2 inches of snow accumulation Sunday evening
near/east of the Miss River with maybe a period of some freezing
drizzle or even just drizzle as low level warming wins out for a
time, before cold advection kicks back into great on Monday.

Beyond that, looking pretty quiet later Monday through Tuesday night
as high pressure gradually drifts across the region, with perhaps
some lingering flurries on Monday as clouds hang in and out of the
dendritic growth region. Focus will then be on Wednesday with hints
of yet another stronger shortwave dropping toward the area. This one
has quite a bit more uncertainty associated with it with regard to
placement, with poor run-to-run consistency not helping this
forecaster`s confidence just yet. Perhaps of more interest past
midweek is an increasing signal we may relax the coldest air across
the area as our high-latitude stronger blocking pattern starts to
break down, potentially allowing for temperatures to rebound back
above normal for a period of time late week or next weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1135 AM CST Sat Dec 9 2017

MVFR stratocumulus currently at KLSE/KRST will gradually lift
this afternoon, after which VFR conditions will be the rule
through tonight. Some northwest breezes this afternoon will
diminish and then shift to the west-southwest late this afternoon
and evening. Then, expect a dry surface trough to move through
Sunday morning. Behind this trough, winds will shift back to the
northwest with cloud bases likely to drop below 3000 ft agl.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...Boyne
LONG TERM...Lawrence
AVIATION...Rogers



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