Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 261107

Area Forecast Discussion
National Weather Service La Crosse WI
607 AM 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 12Z TAFS through 12Z Tuesday morning)
Issued at 607 AM CDT Mon Sep 26 2016

Strong northwest winds of 13 to 18 kts with gusts of 22 to 36 kts
are expected at the TAF sites today. The strongest winds will be
across the open areas of southeast Minnesota and northeast Iowa.
Otherwise, a scattered to broken cumulus deck will develop today
with cloud bases around 6 kft. Look for the cumulus deck to
dissipate by early this evening. Winds will also diminish  with
the loss of daytime heating. Will have to keep a close eye on the
potential for low level wind shear tonight as surface winds drop
off to around 10 kts.




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