Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 090139
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
739 PM CST Thu Dec 8 2016

.UPDATE...
Issued at 739 PM CST Thu Dec 8 2016

Quick updated to extend a flurry mention right on through the
night and into at least midday Friday. Current satellite pics tell
the story, with lots of stratus/stratocumulus beneath cold pool
aloft to our north, slowly sliding south in our direction. Given
the northerly low level wind trajectories through the night, don`t
see why clouds won`t linger all night long (and into Friday as
well), with weak cold advection through the night also helping to
reinforce an already stout inversion below 850mb per regional
RAOBs. With the cloud deck pretty much squarely in the DGZ, we
should maintain widespread "snow globe" flurries/light snow
showers all night long, but with little in the way of any
accumulation. Hoping we might actually see a brief window of some
clearing tomorrow as our winds become westerly and drag in some
drier air out that way, but not going to hold my breath just yet.

&&

.SHORT TERM...(Tonight through Friday Night)
Issued at 210 PM CST Thu Dec 8 2016

Deep,cold cyclonic flow dominating most of the CONUS. Locally, it`s
another day dominated by clouds and scattered flurries with
temperatures in the upper teens to middle 20s. Fairly brisk
conditions as well withe northwest winds generally in the 10 to 20
mph range, gusting to near 30 mph across portions of southeast MN
and northeast IA. This was producing wind chills mainly in the
single digits above zero.

For tonight, looking for shortwave ridging to move in with
stratocumulus cloud cover thinning some but not dissipating
completely under increasing subsidence. With thinning clouds, look
for the flurries to come to an end. Still enough surface pressure
gradient to produce northwest winds around 10 mph. These winds,
combined with temperatures dropping into the lower/middle teens,
will produce predawn wind chills in the single digits above and
below zero.

Friday is looking quiet with partial sunshine as surface high
pressure drifts eastward across the region. Otherwise, the chill
continues with highs only topping off in the teens. Variable
cloudiness and light winds should allow temperatures to cool into
the single digits/lower teens above zero. Will have to watch these
temperatures as less cloud would allow for colder overnight lows.

.LONG TERM...(Saturday through Thursday)
Issued at 210 PM CST Thu Dec 8 2016

Attention turns to an incoming weak mid-level trough with surface
low pressure over the Central Plains. Strong isentropic upglide
ahead of this pushes likelihood of snow into our area
Saturday/Saturday night with the potential for some occasional
higher snow rates of 1 inch/hr, especially given fairly strong 700-
500mb frontogenesis/potential for some embedded elevated instability.
Forcing from this wave pushes east Sunday with a brief respite.
Bottom line...at this point...looks like 3-6 inches for areas south
of I-94... heaviest across northeast IA into far southwest WI from
Saturday afternoon into Sunday night. This would likely warrant
eventual Winter Weather Advisory headlines...but will hold off for
now as there is still some uncertainty for exact location/snow
amounts.

Another trough/wave of low pressure moves out of the Central Plains
into IL and the Great Lakes Sunday night into Monday. Looks like our
area will be on the northern periphery of better forcing from this
wave and therefore will have to be monitored as it has the potential
to produce a couple more inches of snowfall for areas south of I-90.

Another chance of snow set for late Monday night/Tuesday morning as
an Arctic front pushes through the area. Will have to keep an eye on
this feature as well as there the potential for some vigorous snow
shower activity and potential for some blowing of this snow in
strong pressure gradient/cold air advection. Look for lows Monday
night mostly in the single digits above zero with falling
temperatures Tuesday in cold air advection. Wind chills will be a
factor, falling into the teens/near 20 below zero during the
afternoon.

Dry and much colder than normal temperatures for Wednesday and
Thursday as Arctic airmass settles into the Upper Mississippi River
Valley/Great Lakes regions. Model consensus has lows in the single
digits below zero with highs mostly in the single digits above zero.
Normal highs for next week are in the middle 20s to lower 30s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 525 PM CST Thu Dec 8 2016

Stop me if you`ve heard this forecast before. Widespread stratus
continues to encompass the region, though conditions have recently
improved to VFR at LSE as some drier air has wrapped in from the
west. That trend toward VFR ceilings should remain for most of the
night at LSE while conditions mainly hold in the 2500-3000 ft
range at RST with periods of flurries continuing as well. We may
see another bout of lowering ceilings back to MVFR levels for all
areas toward sunrise as some shallow colder air arrives, but with
low level winds slowly shifting westerly into Friday, we do
anticipate seeing a break in the stratus for a time. Just how fast
stratus departs remains a question, but a rough guess would be
early to mid afternoon for both LSE and RST.


&&

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

$$

UPDATE...Lawrence
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...Lawrence



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