Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 230347

Area Forecast Discussion
National Weather Service La Crosse WI
1047 PM CDT Tue Jun 22 2021

.SHORT TERM...(This evening through Wednesday)
Issued at 226 PM CDT Tue Jun 22 2021

At 2 PM, the surface ridge over the Ohio/Tennessee river valleys
continues to move southeast of the area. As this occurs, the
surface dew points are starting to rise west of the Mississippi
River Valley. The dew points will rise into the 50s tonight and
into the lower 60s on Wednesday.

As the 850 mb moisture transport increases in Iowa late this
afternoon and evening ahead of a shortwave trough, showers and
storms will develop. This precipitation will be found mainly south
of Interstate 90 tonight and Wednesday morning. While the 0-3 km
shear is in the 30 to 40 knot range, 0-1 km ML CAPE is only up to
350 J/kg, so not expecting any severe storms. Rainfall amounts
will be generally less than a quarter of an inch.

Low temperatures tonight will be in the mid to upper 40s in central
and north-central Wisconsin, and in the 50s for the remainder of the
area.  High temperatures on Wednesday will range from the upper 70s
to mid-80s.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 226 PM CDT Tue Jun 22 2021

Main forecast concerns in the long term are on chances for showers
and thunderstorms.

A cold front edges southeastward across Minnesota Wednesday into
Wednesday night. Showers and thunderstorms are expected to develop
along the front over northern Minnesota Wednesday evening.  A
complex of storms is expected to push southeast over time
Wednesday night into Thursday morning but will most likely be
weakening as they approach west-central Wisconsin. Low level
moisture streaming northward ahead of the approaching front will
drive dew points into the mid to upper 60s, possibly to around
around 70. So with plenty of moisture to work with and a the front
sliding into the area during the day on Thursday, expect
scattered showers and thunderstorms to develop. MUCAPE climbs into
the 1500 to 2500 J/kg range by early afternoon Thursday but shear
is weak with 0-3 km bulk shear values of 15 to 20 kts. Of greater
concern may be the potential for locally heavy rainfall with
precipitable water values approaching 180 percent of normal and
warm cloud depth of around 4 kft. This is good news for those
areas that need the rainfall, but rainfall rates could be high
enough to cause some issues. Will have to monitor this closely. A
broad trough then sets up across the region Friday into the
weekend with continued chances for showers and thunderstorms.
Depending on where the frontal boundary sets up over the region, a
few more rounds of heavier rain are possible over portions of
Iowa into southern Wisconsin Friday into Saturday.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1040 PM CDT Tue Jun 22 2021

Potential for low ceilings moving into the TAF sites towards
daybreak has diminished. The warm front over Iowa has retreated
further south, with currently less low level moisture pooling
over the central part of the state than earlier model runs had
suggested. May still see few to sct MVFR clouds sneak into the TAF
sites late tonight, but likelihood of any low ceilings developing
now looks very low. Only VFR cumulus expected during the day
Wednesday. Light southeast winds the rest of tonight will become
more southerly by daybreak, then southwesterly in the afternoon.
Will see a slight uptick in winds briefly in the late afternoon to
early evening with some gusts of 20 to 25 knots possible.




LONG TERM...Wetenkamp
AVIATION...Kurz is the U.S. government's official web portal to all federal, state and local government web resources and services.