Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 280440
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1140 PM CDT WED JUL 27 2016

.SHORT TERM...(This evening through Thursday)
Issued at 343 PM CDT Wed Jul 27 2016

Main forecast concerns in the short-term:

1)Thunderstorms through early this evening with the potential for an
isolated severe storm and a possible low end NST (non-supercell
tornado) threat along with marginal severe hail.

2)How long will the showers and isolated thunderstorms hold on in
the inverted trough feature on Thursday.

First off, the deep layer shear and CAPE is just enough late this
afternoon into early this evening to support brief strong to
severe storms. The CAPE will diminish with the loss of daytime
heating late this afternoon into this evening and we should see a
diminish in thunderstorms, at least weakening of any stronger
storms. We are keeping a close watch on a warm front/old outflow
boundary in place along near the Interstate 94 corridor late this
afternoon. A few storms have been developing along it but they
have not stayed with the boundary so the potential for an NST has
been low. Further to the west a cold front is pushing east
towards southeast Minnesota and northeast Iowa. We are watching
the front closely as storms are developing along it. It is
interesting that we have seen a few brief supercell structures
over northwest Wisconsin into the Twin Cities area this afternoon.
Just enough CAPE and Shear to support this. A shortwave trough/MCV
(mesoscale convective vortex) slides into the area tonight and
will keep scattered showers and thunderstorms going. Then as the
trough edges southeast late tonight into Thursday morning an
inverted surface trough lingers across the area and and we will
see continued scattered showers and isolated thunderstorms along
it, but shear is even weaker on Thursday so not anticipating any
severe storms. Showers and storms will gradually taper off
Thursday afternoon into Thursday evening as high pressure builds
in from the north. Will have to keep a close eye on any fog
potential as skies clear under the high Thursday night across
portions of central into northern Wisconsin.

.LONG TERM...(Thursday night through Wednesday)
Issued at 343 PM CDT Wed Jul 27 2016

Surface high pressure will be the dominant weather feature going
into the weekend. Forecast models are trying to generate some low
precipitation chances at times Friday afternoon and again
Saturday afternoon, mainly across southwest Wisconsin but this
appears overdone. Will maintain a model consensus blend, producing
low rain chances, but this period mostly likely will be dry. Plan
on highs cooling down for Thursday through Saturday with highs
mainly in the 70s. Warmer temperatures return next week along with
chances for showers and thunderstorms as we look to bring more
unstable air back into the region as a series of shortwaves move
through.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1140 PM CDT Wed Jul 27 2016

With majority of showers and storms now north and east of TAF
airfields, primary challenge overnight into Thursday morning will
be lowering ceilings/visibility. Forecast guidance in good
agreement, showing cloud bases lowering to IFR/low MVFR tonight
with at least MVFR visibility in mist. These lower conditions will
be very slow to improve Thursday, but expect gradual lifting into
the afternoon.

Scattered showers/embedded thunderstorms return late Thursday
morning and through the afternoon along an inverted surface
trough. Better chances may be along the MS River impacting KLSE,
but introduced VCTS at both airfields through the afternoon for
now. Additional refinement will be needed with later forecasts.
Winds will be light through the period, generally from the north-
northeast.

&&

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

$$

SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...ROGERS



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