Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 261727

Area Forecast Discussion
National Weather Service La Crosse WI
1227 PM CDT Mon Sep 26 2016

.SHORT TERM...(Today through Tuesday night)
Issued at 312 AM CDT Mon Sep 26 2016

Water vapor imagery along with RAP 500mb analysis showing a deep
trough extending south across MN/IA. At the surface...deep low
pressure around 999mb over southern Ontario with a cold front
extending southward through western Lower MI into Indiana. Cooler
air filtering into the region this morning on westerly winds with
temperatures as of 3 am ranging from the upper 40s to the middle 50s.

For today...deep cyclonic flow with tight pressure gradient will
reside over the region for cooler/blustery conditions. Fairly deep
mixing to 800mb expected to produce wind gusts in the 30-40mph
range out of the west/northwest. Winds will be shy of the need for a
wind advisory but thinking with very saturated ground..some trees
may be susceptible to toppling. May issue a special weather
statement this morning for this concern. Steep lapse
rates/instability also expected to produce a pretty good field of
cumulus and a good chance of showers for areas north of I-94.
Otherwise, look for highs ranging from the middle 50s to the lower

Winds expected to die down this evening with skies remaining mostly
cloudy across north central WI along with a slight chance of showers.
Skies expected to be mostly clear across the rest of the area.
Looks like a chilly night with lows falling into the 40s.

Deep/cool cyclonic flow continues through Tuesday as mid-level low
closes off and moves southward into the area. Models also showing a
lobe of pv-advection dropping through the region Tuesday afternoon
into Tuesday night, bringing with it a chance for showers. Plan on
highs Tuesday in the upper 50s/lower 60s with lows Tuesday night in
the 40s.

.LONG TERM...(Wednesday through Sunday)
Issued at 312 AM CDT Mon Sep 26 2016

Deep cyclonic flow lingers over the region as the closed low moves
farther southward into Indiana. This will keep a small chance of
showers going across far southwest into central WI. Otherwise...
another slightly cooler than normal day on tap with highs in the 60-
65 degree range.

Thursday through Friday look dry and slightly warmer as the closed
low moves farther into the Ohio River Valley which allows a ridge of
high pressure to build over the region. look for highs in the 65-70
degree range and overnight lows in the middle 40s to the lower 50s.

Latest GFS/ECMWF a bit at odds on how to handle closed low saturday
through Sunday. The GFS maintains ridging across the region while
the last 2 runs of the ECMWF show the low retrograding back toward
the region. For now, went with a consensus which keeps us dry with
highs in the 65-70 degree range/lows in the upper 40 to lower 50s.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1227 PM CDT Mon Sep 26 2016

Brisk/gusty W to NW sfc/low level winds will be the main issue at
the TAF sites this period. Good VFR conditions expected thru
tonight/Tue morning as the drier W/NW low/mid level flow continues
over MN/IA/WI. Perhaps a few diurnal cu/strato-cu in the 5K-6K ft
range during the afternoons. Tighter pressure gradient over the area
this afternoon along with warming/mixing to around 850mb to result
in W/NW winds 15-25kt G25-35kt thru about 23z, with the stronger
winds across the higher terrain, open country areas like KRST. Winds
to diminish to 10-15kts this evening with diurnal cooling/
stabilization. May yet need a mention for LLWS later tonight/early
Tue if sfc winds drop below 10kts, as winds around 2K ft progged to
be in the 30-35kt range around 12z Tue. Winds increase again later
Tue morning with diurnal warming/deeper mixing. Some relax of the
gradient and winds aloft for Tue, with winds after 15z mostly 10-
20kt G20-25kt.




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