Area Forecast Discussion
Issued by NWS La Crosse, WI

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042
FXUS63 KARX 260812
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
312 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
60s.

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 06Z TAFS through 06Z Monday night)
Issued at 1143 PM CDT Sun Sep 25 2016

The back edge of the lower VFR ceilings has worked through both
airports this evening. However, there is another area of mid level
clouds rotating southeast across Minnesota that the 26.03Z RAP
suggests could bring a ceiling back into both airports for a while
overnight. These clouds should clear out before sunrise for a
sunny start to Monday before scattered to broken cumulus form late
in the morning or early in the afternoon. The 26.00Z NAM has
backed off on the amount of moisture available for KRST and no
longer suggests a VFR ceiling will form there Monday afternoon.
The other issue to contend with Monday will be the winds. A pretty
tight pressure gradient will be over the Upper Midwest and with
steep lapse rated developing during the morning this should lead
to gusts of 25 to 30 knots for a good share of the day.

&&

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

$$

SHORT TERM...DAS
LONG TERM....DAS
AVIATION...04



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