Area Forecast Discussion
Issued by NWS La Crosse, WI

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325
FXUS63 KARX 230820
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
320 AM CDT Tue May 23 2017

.SHORT TERM...(Today through Wednesday night)
Issued at 320 AM CDT Tue May 23 2017

Water vapor imagery early this morning indicated a well-defined
upper low across northern Minnesota. The upper low will move
southward across Minnesota and Iowa today and into the Mid-
Mississippi Valley on Wednesday. Expect scattered showers today
with the upper low dropping south and an inverted surface trough
oriented from northwest to southeast across the area. There may
be some weak instability with cold temps aloft and steepening
low-level lapse rates, so an isolated thunderstorm is possible.
High temps should hold in the upper 50s to low 60s with the
widespread cloud cover.

Shower chances will continue into tonight as a shortwave rotates
around the upper low with the highest chances across western
Wisconsin. A few showers may linger on Wednesday before the upper
low slides south and east of the area. However, temps will remain
on the cool side with highs in the low to mid 60s.

.LONG TERM...(Thursday through Monday)
Issued at 320 AM CDT Tue May 23 2017

The upper trough will slowly migrate into the eastern Great Lakes on
Thursday with weak surface high pressure and brief mid-level
shortwave ridging building into the area. The upper level flow will
become westerly to southwesterly late this week as an upper
trough moves into the northern Rockies. 23.00Z global models drag
a weak surface front into the area on Friday, with some minor
timing differences. There are some low end rain chances Thursday
night/Friday night with the weak surface boundary approaching and
a few embedded upper shortwaves ejecting through the Midwest.
Temps will warm back into the upper 60s to low 70s for Thursday
and Friday.

For the Memorial Day weekend, the upper trough to the west will
slide eastward towards the Great Lakes. 23.00Z global models
continue to show some differences with the progression of the
upper trough and timing of precip chances. However, given the
pattern, there may be showery periods at times heading into the
weekend, with highs generally in the 60s to low 70s, but likely
plenty of dry hours as well.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1120 PM CDT Mon May 22 2017

Cigs: looking at vfr cigs overnight-Tue morning as upper level
trough/low drops south/southeast through the region. Models
suggesting that the clouds will continue to lower Tue
afternoon/evening - with the potential for ifr/mvfr. However, some
of that is tied to an expanding stratus layer northwest of the
system`s sfc low/coupled with the upper level low. Not confident in
this scenario. Going to hold with MVFR/near MVFR cigs for both
KRST/KLSE from Tue afternoon through the period for now. Expect some
refinement in the forecast later in the day as trends become more
clear.

WX/vsby: a few lingering showers through about 08z or so, then the
threat for more showers returns by late morning/early afternoon -
especially for KRST (cold air advection/perky low level lapse rates
and the upper level low). Going -shra for KRST for now, with VCSH at
KLSE. Expect a decrease in coverage by 00z Wed.

Winds: mostly a north direction overnight - holding there through
Tue night.

&&

.HYDROLOGY...
Issued at 320 AM CDT Tue May 23 2017

Minor flooding is expected along portions of the Mississippi River
this week and also the Trempealeau River at Dodge as a result of the
recent heavy rains. Monitor river levels closely if you have
interests along these rivers.

&&

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

$$

SHORT TERM...JM
LONG TERM...JM
AVIATION...Rieck
HYDROLOGY...JM



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