Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 231135

Area Forecast Discussion
National Weather Service La Crosse WI
635 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 12Z TAFS through 12Z Wednesday morning)
Issued at 635 AM CDT Tue May 23 2017

Overcast skies will be the rule at KRST/KLSE through the period.
MVFR ceilings at KLSE will persist through the afternoon/evening
and then lower to IFR overnight. VFR ceilings at KRST will
gradually give way to MVFR later this afternoon and eventually IFR
overnight. Timing of ceiling changes will need fine-tuning
through the day. Scattered showers will be possible through the
day with the best chances this afternoon. While isolated
thunderstorms are also possible, timing/coverage uncertainty
precludes mention in the 12Z TAFs. Light northerly winds will be
the rule through the period.


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.




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