Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 201810

Area Forecast Discussion
National Weather Service La Crosse WI
110 PM CDT Tue Mar 20 2018

.SHORT TERM...(Tonight through Wednesday Night)
Issued at 110 PM CDT Tue Mar 20 2018

GOES-East water vapor showing a mid-level area of vorticity rotating
southeast along the MN/IA border while another mid-level circulation
was passing eastward through Manitoba. Stretching deformation axis/f-
gen between these two systems was generating a few pockets of light
snow across MN/western IA with just broken to overcast altocumulus/
cirrus east of the Mississippi River. Otherwise, temperatures were a
bit on the cool side today with readings at 1PM in the 30s.

The two aforementioned systems will pass the north and south of the
area tonight with a ridge of high pressure building in after
midnight into Wednesday. This will provide clearing skies,
especially by later Wednesday morning. Plan on lows tonight in the
upper teens to middle 20s with highs Wednesday afternoon in the
middle 30s to the middle 40s. High pressure remains in control
Wednesday night for partly cloudy skies and lows in the teens to
upper 20s.

.LONG TERM...(Thursday through Tuesday)
Issued at 110 PM CDT Tue Mar 20 2018

High pressure will continue to be the dominant weather feature
through Thursday for dry and milder conditions. Look for highs in
the 40s.

A small chance of rain moves in west of the Mississippi River Friday
afternoon in advance of a mid-level trough pushing out of the
Plains. However, models runs have been drying this out the last
couple of runs given dry northeast flow. Otherwise, plan on highs
again in the 40s under partly sunny skies.

Mid-level trough and surface low push out of the Plains toward MO
Friday night with precipitation pushing into areas basically south
of I-94 by morning. Dry northeast flow/evaporative cooling will
likely cause a transition from rain to all snow with some minor
accumulations possible as low temperatures drop into the 20s/lower

Precipitation chances continue Saturday, again mainly south of I-94,
as the mid-level trough passes overhead and surface low passes to
the south. Precipitation outcome will likely by some light snow in
the morning, mixing with or changing to rain by afternoon as highs
climb into the middle 30s to a few lower 40s. Again, any snow
accumulations look pretty minor with no a lot of impact anticipated
at his time.

Latest 20.12Z gfs/EC keep us dry Sunday as Hudson`s Bay high
pressure/dry northeast flow regain control across the area.
Temperatures look to be right around seasonal norms with highs in
the upper 30s to the middle 40s.

A small chance of a rain/snow mix pushes into the area Sunday night,
mainly along/west of the Mississippi River, as increasing moisture
transport/isentropic lift take place ahead of a mid-level trough
moving through the Northern Plains.

Some timing inconsistencies crop up between the GFS/EC next Monday
and Tuesday. GFS is much more aggressive/progressive with incoming
trough whereas the EC keeps amplified ridge over us/drier through at
least Monday evening. Will go with blend/consensus for now which
yield a small chance rain or rain/snow mix.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1233 PM CDT Tue Mar 20 2018

Dry east and northeast winds will keep the snow and MVFR ceilings
west and southwest of the TAF sites through the period. Ceilings
will be around 6K feet at KRST and 10K feet at KLSE.




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