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Area forecast discussion 
National Weather Service La Crosse WI
312 am CST sun Feb 14 2016

Short term...(today through Tuesday night)
issued at 312 am CST sun Feb 14 2016

More winter weather fun on the day through the day...with the main
focus on accumulation potential. Early morning analysis shows the
situation actually playing out about as expected (can't always say
that's the case)...with an earlier lead fgen band of snow working
through central/southeast Iowa...while another area of broadening
snow is expanding through the southwest half or so of the County Warning Area. That
latter snow comes within a broad zone of modest deep layer warm
advection ascent ahead of quite the stronger shortwave working
southeast out of South Dakota. That feature will make a run through
the region later today...with snow continuing to expand eastward
across much of the area into midday...likely becoming most focused
in intensity from south central Minnesota down into parts of
northeast Iowa and far southwest Wisconsin...tied to the strongest
ascent and tighter fgen circulation laid out across the area.
Meanwhile...persistent drier air and weaker forcing will tend to
mute the eastward extent of snowfall...such that not much (if any)
may fall north of I-94 through noon. Still...as the upper wave
itself tracks through the area this afternoon into this evening...we
should finally see some lighter snows overtake those areas...while
lingering over the remainder of the area through at least 6 PM...and
likely closer to midnight into Wisconsin where deeper moisture
lingers the longest.

As for accumulation...still looking for a stripe of 2-4 inches
across the southwest half or so of the County Warning Area (a little lower than
initially expected)...with the highest amounts into northeast Iowa
and down toward Grant County Wisconsin tied to the strongest burst
of warm advection ascent through midday. Not hurting those amounts
will be higher ratios...with modest Omega pegged through a rather
deep dgz. In these areas will maintain the going Winter Weather
Advisory...though honestly some spots may end up falling short of
criteria per radar trends. Elsewhere...amounts should taper to
around an inch north of I-94 but here again ratios may help US
with accumulation despite lower actual precipitation amounts. Not so
sure blowing snow will be a big factor given marginal winds but
with the "fluff factor" to the snow and speeds of 15-20 knots...no
doubt there will be some patchy blowing (more like drifting) snow
over the open areas west of the Mississippi.

Passage of a weaker secondary trough may try to linger some lighter
snows across the area through much of tonight...with lower clouds
likely lingering through the day on Monday as moisture gets trapped
beneath a building inversion. Another in a series of upper waves
looks to dive from the northern plains down through western Iowa
later Monday night into Tuesday morning...though with still a few
questions about the exact placement of this feature. Per a multi-
model consensus...the NAM remains an outlier in driving a band of
precipitation more through the County Warning Area...and prefer a more western solution
given trends over the past few days. That idea suggests the more
appreciable precipitation will stay mainly west of the County Warning Area...with
some lighter accumulation just clipping areas west of Highway 63. As
that system departs...low level ridging looks to arrive by Tuesday
night with clearing skies and perhaps some temperatures dipping toward the
0 degree mark north of I-90 pending timing of clearing and wind
trends.

Long term...(wednesday through saturday)
issued at 312 am CST sun Feb 14 2016

Looking like a nice break in the action toward Wednesday and much of
Thursday as broad lower level ridging rules The Roost across the
region...though a very tight pressure gradient by Thursday should
deliver a pretty good batch of southerly winds. After that...still
quite a few questions about cloud trends and temperatures later
Thursday into Friday as quite the airmass moderation gets underway
in advance of a fast moving trough through the western states. Given
the magnitude of warm advection ascent later Thursday/Thursday
night...have to believe we are in for at least a period of lower
stratus development as some very warm air (and more importantly...
higher dew points) make a run up and over the deeper snow pack.

Could ultimately see some drizzle and/or light rain from this setup
for a time...and can't rule out a small freezing rain threat
northeast areas given preceding colder temperatures and frozen
ground. Otherwise...still waiting to see how warm we can get on
Friday...with plenty of signals we may break out into the warm
sector as low pressure passes over Lake Superior...with at least
some potential for spots to make a run at 50 degrees...though with
our current forecast tempered by lots of remaining questions
regarding cloud cover. Looking cooler and potentially windy into the
weekend...but with limited precipitation threat as the main storm track
holds north of the area.

&&

Aviation...(for the 06z tafs through 06z Sunday night)
issued at 1138 PM CST Sat Feb 13 2016

Snow will overspread the taf sites tonight into Sunday morning
with conditions gradually lowering to IFR as low levels saturate.
Plan on visibilities falling into the 1-3 sm range with ceilings
falling to around 900 feet at times. Also...southeast winds will
increase Sunday morning into the 13 to 18 knots range...with gusts
to around 25 kts. The snow and periods of IFR conditions will
persist into Sunday afternoon...then snow tapers off during the
middle to late afternoon hours. A secondary shortwave moves in and we
could see another round of light snow late this afternoon into
this evening.

&&

Arx watches/warnings/advisories...
WI...Winter Weather Advisory until 6 PM CST this evening for wiz054-
061.

Minnesota...Winter Weather Advisory until noon CST today for mnz086-087-
094>096.

Iowa...Winter Weather Advisory until 6 PM CST this evening for
iaz008>011-018-019-029-030.

&&

$$

Short term...Lawrence
long term...Lawrence
aviation...wetenkamp

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