Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 011144

Area Forecast Discussion
National Weather Service La Crosse WI
544 AM CST Wed Mar 1 2017

.SHORT TERM...(Today through Thursday)
Issued at 330 AM CST Wed Mar 1 2017

Accumulating snowfall potential today will be the main impactful
weather concern.

Broad surface low pressure across southern Michigan will gradually
intensify as it moves east today as an upper shortwave approaches
from the west. As the low continues eastward, boundary layer thermal
profiles will continue to cool with sustained low-level cold
advection. A period of strong mid/upper level QG forcing will
overspread the region this morning, with precip becoming more
widespread and transitioning to snow within the deformation zone
of the departing low pressure system. There has been just a
slight northward trend in model guidance compared with yesterday.
As a result, using a consensus blend of QPF did bring higher
precip amounts slightly farther north and west into central WI. As
a result, expanded the Winter Weather Advisory to also include
Clark, Jackson and Monroe counties. 3-4" are expected in the
advisory area, tapering to 1-3" farther southwest. Will have to
monitor for any persistent heavier frontogenetical snow bands that
could lead to locally heavier snow amounts, as some high res model
runs have indicated. Snowfall will decrease from the west through
the afternoon.

With relatively warm ground and much of the snow falling during the
day, how much snow accumulates will be dependent on snow rates.
Snow rates of up to 1"/hr are possible for a time this morning,
especially across central WI, which would aid in accumulations and
increase travel impacts. Although northwest winds will be gusty at
times, do not expect significant impacts from the winds.

The first in a series of weaker upper waves in northwest flow will
move through tonight. It could bring some light snow/flurries, but
with little accumulation.

A fast-moving upper wave will move through on Thursday. Impacts from
this system look minor, although model guidance still differs some
on the track/intensity details. The 01.00Z ECMWF is weaker and
drier, while the GFS/NAM would support light snow accumulations of
generally under an inch, with the NAM a little farther north with
the precip over southeast MN into western WI. Forecast soundings
show steep low-level lapse rates developing behind the system, so
winds may become gusty, especially over SE MN/NE IA, in addition
to any snow shower activity.

.LONG TERM...(Thursday night through Tuesday)
Issued at 330 AM CST Wed Mar 1 2017

High pressure will sink south across the region Thursday night and
Friday signaling a return to quieter weather into the weekend. The
surface high will pass to the east later on Friday with winds
turning around to the south. The warm advection really kicks in on
Friday night, with some guidance still painting light precip within
stronger areas of 850-700 mb warm advection, but should the area see
any precip, it looks very light.

Otherwise, temps climb back above average for the weekend with dry
weather expected as upper ridging spreads back across the central
US. High by Sunday likely will be back well into the 50s as 925
mb temps jump to 9-11C.

A large upper trough will then approach early next week bringing the
next better chance for precipitation. However, the global models
have been inconsistent in the evolution of the trough as it moves
out of the Rockies. The GFS/ECMWF keep the surface low well north,
suggesting mostly rain, though. Temps will cool behind the system,
but overall it looks like mild temps will continue right into next


.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 544 AM CST Wed Mar 1 2017

Colder was gradually spreading in and has changed the rain over to
light snow at KRST and should do so soon at KLSE as well and plan
to start both forecasts with just light snow. The snow should
continue for much of the morning before exiting to the east as the
short wave trough currently over northwest Iowa moves across the
region. The visibility will quickly improve to VFR once the snow
ends but the ceilings will be slower to respond staying IFR/MVFR
well into the afternoon. The ceilings should then improve to VFR
during the evening. Another fast moving system will be approaching
from the northwest late tonight. This system looks like it will
bring in MVFR conditions not long after 02.12Z.


Issued at 330 AM CST Wed Mar 1 2017

River levels remain elevated on many area waterways. Portions of the
Mississippi are expected to continue to see rises over the next few
days. The Mississippi River near McGregor is expected to reach
minor flood stage later this week, with mainly in bank rises along
other portions of the river.


WI...Winter Weather Advisory until 6 PM CST this evening for WIZ029-



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