Area Forecast Discussion
Issued by NWS La Crosse, WI

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953
FXUS63 KARX 272043
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
343 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 18Z TAFS through 18Z Thursday morning)
Issued at 1229 PM CDT Wed Jul 27 2016

Low pressure, a couple of fronts and a couple of disturbances aloft
will move toward and across the area this afternoon into Thu
morning.  As these features approach, sct SHRA/TSRA expected to move
into the TAF sites late this afternoon into much of this evening.
Finer details of timing/coverage of TSRA thru this evening remain
unclear, and left thunder mention as VCTS at both KRST/KLSE for now.
By later tonight and for Thu morning, deeper layered convergence
sets up over the fcst area as a sfc-700mb low/trough drifts slowly
across MN/WI. this convergence/lift and a rather moist airmass looks
to result in numerous SHRA and BR, along with MVFR cigs/vsbys,
around the TAF sites for most of the second half of this TAF period.
Some IFR cigs/vsbys in BR/SHRA likely a couple hours either side of
sunrise Thu and added a tempo period for this in the 09-13z time-
frame. Conditions to slowly improve Thu afternoon as the low/trough
move east of the area and cooler/drier high pressure starts to build
in.


&&

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

$$

SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION.....RRS



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