Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 262335
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
535 PM CST Sun Feb 26 2017

.SHORT TERM...(This evening through Monday)
Issued at 332 PM CST Sun Feb 26 2017

At 3 PM, a couple of bands of mid and high clouds were
transitioning east across the area. These clouds were associated
with a short wave moving across northern Wisconsin. Temperatures
were in the lower 30s where the heavy snow still lingers from
Thursday night and Friday. Elsewhere temperatures ranged from the
mid-30s to lower 40s.

For tonight and Monday, a series of weak systems will move across
northern Minnesota and northern Wisconsin. Other than some clouds
mainly north of Interstate 90, it will have little impact on our
weather. The high temperatures for Monday were cooled a bit from
guidance where the heavy snow band still exists. Meanwhile, the
temperatures were warmed in the Mississippi and Wisconsin River
valleys due to the temperature guidance under performing over the
past 2 days.

.LONG TERM...(Monday night through Sunday)
Issued at 332 PM CST Sun Feb 26 2017

On Monday night, a short wave trough and surface warm front will
move quickly northeast across the area. Southerly winds and strong
warm air advection ahead of this system will warm the atmospheric
column enough that any precipitation that occurs will be in the
form of liquid. For much of the area, it still looks like the
surface temperatures will be warm enough that the precipitation
will be rain. However, may have to watch the temperatures at the
onset of the precipitation north of Interstate 94. Some models
suggest that temperatures may be cold enough at the onset for
the possibility of some freezing rain.

On Tuesday, there is still some uncertainty on the location of the
low pressure area. The GFS is the far enough northwest that we
will be well entrenched in the warm sector of this system that we
could potentially be dry. Meanwhile the GEM, ECMWF, and NAM have
the low further southeast. In this scenario, we could see off and
on rain throughout the day. With the models in general agreement
that the most unstable CAPES could climb up to 250 J/kg, isolated
thunder was added to northeast Iowa and southwest Wisconsin during
the afternoon.

On Tuesday night and Wednesday, there continues to be differing
solutions on how fast will the precipitation exit the region and
when the atmospheric column will cool sufficiency for the
precipitation to transition over to snow. For now, just went with
a model blend. Regardless of the solution, any precipitation that
falls during this time frame will be likely on the light side.

From Wednesday night into Thursday, the models continue to
struggle with the positioning of a short wave moving southeast
through the region. In addition to this, there are additional
questions on whether there will be enough saturation for snow to
develop. At this time, the GFS and GEM are by far the robust with
this system. However, the GFS is farther north and it would
produce 1 to 3 inches of snow south of Interstate 94. Meanwhile
the GEM would have its snow mainly south of Interstate 80. The
ECMWF has a much weaker surface low and as a result it does not
saturate until it has moved southeast of the area.

Beyond this time period, there are periodic small precipitation
chances. However there is little model consistency (run to run and
from model to model), so confidence is extremely low.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 535 PM CST Sun Feb 26 2017

VFR conditions will be the rule at KRST/KLSE through the period as
high pressure moves across the region this evening and overnight.
Some VFR ceilings in the 6000 to 8000 ft agl layer currently
across SD could impact TAF sites overnight, but most should pass
just to the north with only cirrus overhead. Light southwest wind
this evening will shift to the south tonight as the surface ridge
axis pushes east. Some forecast guidance hints at the possibility
for some fog development overnight, but highest probabilities are
south of TAF airfields, so will not include any reductions in
visibility at this time. Will monitor observational trends and
amend as necessary.

&&

.HYDROLOGY...
Issued at 332 PM CST Sun Feb 26 2017

Castle Rock Dam on the Wisconsin River has dropped below flood
stage and that warning was canceled this morning. At this time,
only the Yellow River at Necedah is still in flood. For specific
information on these sites, see the latest flood statements.

&&

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

$$

SHORT TERM...Boyne
LONG TERM...Boyne
AVIATION...Rogers
HYDROLOGY...Boyne



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