205
FXUS63 KARX 191953
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
Issued by National Weather Service Des Moines IA
253 PM CDT Mon May 19 2025

.KEY MESSAGES...

- Wet later tonight into Wednesday. 1-3 inches of rain is
  expected south of Interstate 94. The highest totals (2-3
  inches locally as high as 3-4 inches) will be in northeast
  Iowa, southeast Minnesota, and southwest Wisconsin.

- Some cold record high temperatures may be tied to broken on Tuesday

- It will remain cool and dry from Wednesday night into the
  Memorial Day weekend.

&&

.DISCUSSION...
Issued at 227 PM CDT Mon May 19 2025

Wet from Late Tonight into Wednesday

A 500 mb trough and 850 mb closed low pressure area will move
into the area tonight. As this occurs, 850 mb moisture
transport and deep moisture convergence will increase later
tonight and continue into Tuesday evening. The 19.12z HREF
continues to bring 1 to 1.4 inches of precipitable water values
into the region south of Interstate 94. Meanwhile, a dry
easterly flow will result in much lower precipitable water
values (0.4 to 1 inch) for areas north of Interstate 94. Areas
south of Interstate 94 will likely see rainfall amounts of 1 to
3 inches and up to 1 inch (highest near Interstate 94) for the
remainder of the area. The HREF ensemble probability-match mean
suggest that there may be some localized rainfall totals of 3-4
inches in northeast Iowa, southeast Minnesota, and southwest
Wisconsin. With the very dry antecedent conditions over the past
3 weeks, not anticipating any issues with river flooding.

Like the past couple of days, much of the instability remains
south  of the area. The ensemble mean for most unstable CAPEs
remain below 250-500 J/kg across much of northeast Iowa and
southwest Wisconsin. Several CAMs and the rapid update models
/HRRR, RAP/ do depict up to 1000 J/kg of MUCAPE over the far SW
section of the CWA this evening into early tonight. Effective
shear values this evening do exceed 40 kts for a time, although
expecting any cells to quickly congeal into a messy cluster of
storms. As a result, organized severe weather in not expected.

Wednesday Night into the Memorial Day Weekend

In the wake of this system, northwest and north winds will bring
dry and cool air into the region. High temperatures through
Saturday will be primarily in the lower and mid-60s and in the
mid to upper 60s for Sunday. These temperatures will be 5 to 10
F cooler than the seasonal averages for this time of year.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1220 PM CDT Mon May 19 2025

East winds will continue to advect in very dry (dew points in
the lower to mid-30s) into the region this afternoon. This will
result a continual dissipation of the showers west of the
Mississippi River. The CAMs continue to suggest that most of
these showers will not reach KLSE or much of western Wisconsin.
As a result, ceilings and visibilities will be primarily VFR
this afternoon. As a 500 mb shortwave approaches the area and
closed 850 mb low approaches the region tonight, another round
of rain will move into the area. This rain will then continue
into Tuesday. Ceilings will gradually lower to IFR/MVFR
overnight and early Tuesday morning. Visibilities will become
MVFR around 20.08z at KRST and around 20.09z at KLSE. Finally
very strong winds /at or above 50 kts/ in the 1-2k feet AGL
layer will lead to period of LLWS late tonight into early
Tuesday.
&&

.HYDROLOGY...
Issued at 231 PM CDT Mon May 19 2025

With it being very dry across much of the area over the past 3 weeks,
still not overly concerned with river flooding at this time.
While there will likely be some response in area rivers in
northeast Iowa, southeast Minnesota, and southwestern Wisconsin,
it would take much more QPF (3+ inches) to see rivers even
approach action and/or minor flood stage. As a result, soils
and rivers should be able to handle the forecasted rainfall.
However, there may be some ponding of water in more urban or
poor drainage areas.


&&

.CLIMATE...
Issued at 231 PM CDT Mon May 19 2025

Rain and low clouds will result in very little temperature rise
on Tuesday, High temperatures will likely be in the 40s and
lower 50s. These temperatures will be close to the daily record
cold high temperatures for May 20. While La Crosses record of
44F in 1892 looks safe, Rochester`s cold high record of 46F in
1892 might be in jeopardy /current forecast high of 47F/.


&&

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

&&

$$

DISCUSSION...Boyne/Fowle
AVIATION...Boyne/Fowle
HYDROLOGY...Boyne/Fowle
CLIMATE...Boyne/Fowle