Area Forecast Discussion
Issued by NWS La Crosse, WI

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967
FXUS63 KARX 251740
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1240 PM CDT WED MAY 25 2016

.SHORT TERM...(Today and Tonight)
Issued at 302 AM CDT Wed May 25 2016

Streak of minimal convective activity in the area may change later
today. Main focus will be trying to time convection into the area
and any associated severe weather threats from that.

Tracking short wave trough early this morning as it ejects across
the Central Plains in broad southwest flow. Several convective
systems upstream and as wave approaches this morning. Expect much of
this activity to advect into the area, sweeping northeast through
the day. Uncertainties exist exactly how this will happen though.

Some meso-scale guidance suggest convection could split our area,
with one area lifting northeast associated with the wave proper, and
a 2nd complex staying across Iowa, riding northern edge of deeper
moisture gradient and low level moisture transport. Most unstable
CAPE is still fairly limited across the area, and deeper shear is
marginal at best so how organized this activity might be with
regards to severe weather is still in question.

Trends to slow approach of convection has been accounted for in
forecast, but did raise rain chances as main line moves through the
area. Thinking Slight Risk in Day 1 may be a bit overdone given
uncertainties and marginal set up, but could not completely rule
out a few stronger storms or spotty severe weather.

More wholesale changes made for tonight as wave passes and storm
threat drops off pretty quick. Short term model guidance all over
the place with convective development but feel we could see more
subsidence and break in activity once wave passes. Lowered rain
threat towards a dry trend by Thursday morning. Will have to watch
for fog development as well.

.LONG TERM...(Thursday thru Tuesday)
Issued at 302 AM CDT Wed May 25 2016

Noisy pattern to end the week as more short wave energy moves into
the Midwest in southwest flow aloft. First potential wave could
develop another convective complex to the southwest on Thursday but
we will likely be between waves here and could see a relatively
quiet day with warm temperatures. As wave approaches Thursday night,
could see a few storms move in overnight, but timing and overall
marginal set up will likely limit severe weather potential.

Late in the week and into the holiday weekend, medium range guidance
suggesting upper low could eject out of southwest as large scale
upper pattern begins gradual change. This low will likely lead to
more widespread convection with better dynamics and shear, but some
questions about how much instability will be in place this far
north. While rain chances will be on the higher side Friday into
Saturday, unsure how extensive any severe weather risk could be.
These details will have to be worked out later, but proximity of
passing low and associated shear will bear watching.

Upper low passes by Sunday so could see breaks in rain threats for
latter half of holiday weekend, but unsettled zonal flow looks
likely into next week with waves transversing northern states. Off
and on rain threats sort of blanket the later forecast periods but
there could be dry periods in there most certainly. Temperatures
remain seasonal.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1239 PM CDT Wed May 25 2016

Fairly active weather through the next 24 hours. Currently
watching a mid-level trough and associated shra/ts moving
northeast across northeast IA/southeast Mn early this afternoon.
This wave and associated shra/thunder should clear the KRST/KLSE
TAF sites by early this evening. Another wave of low pressure
moves through after midnight into Thursday morning and is
expected to bring in scattered shra/ts activity. Will also have to
contend with mvfr/occasional ifr vis/cig conditions.

&&

.ARX Watches/Warnings/Advisories...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...Shea
LONG TERM...Shea
AVIATION...DAS



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