textproduct: La Crosse

KEY MESSAGES

- Showers and thunderstorms possible (15-45%) this afternoon and evening along and north of Interstate 94.

- Small (20%) potential for a shower in far southwest Wisconsin tomorrow evening. Better chance (50-80%) for rain Thursday into Thursday night but impacts are not expected.

- Much colder temperatures (mid-20s to mid-30s) expected on Friday night. This bring an end to the growing season for some, particularly north of I-94 (20-50% chance to fall below 28).

DISCUSSION

Issued at 147 PM CDT Mon Oct 12 2026

Shower and thunderstorm potential this afternoon and evening

This afternoon into tonight, shortwave currently moving over SD rolls eastward to northern WI. As heights aloft cool ahead of the wave, steep mid-level lapse rates will develop leading to the potential for a shower or thunderstorm in the northern parts of our CWA, north of I-94. That said, warm temperatures in the 700-800mb layer look to both limit overall instability and thunderstorm potential and to keep any activity elevated. Thus, while shear profiles through the column would be supportive of all forms of severe weather, shear through the effective layer of any uncapped parcels is far less supportive. Thus, other than lightning and perhaps a small hailstone, am not concerned about hazards with any thunderstorms that do develop.

Additional precipitation potential Thursday into Thursday night

Still on track for an upper low to barrel over southern Nevada Wednesday and phase with a northern stream trough Thursday with the resulting surface low quickly shifting northeast from the TX Panhandle toward Detroit. Guidance, which previously had large timing differences, has focused on the Thursday/Thursday night period with remaining uncertainty surrounding the exact trajectory of the upper trough. With our forecast area on the northwestern periphery of the surface low, final trajectory will be very important, particularly for locations across southeast MN and north of I-90 in WI. For areas in our southeast, am now carrying 80 PoPs across parts of northeast IA and far southwest WI. Progged 850/925/sfc temperatures in operational GFS/EC/CMC still look to remain above freezing during the event and 12.13z NBM, while having a non-zero (specifically, 1%) chance for snow in parts of Taylor County, is pretty much all rain, so have continued with an all rain forecast.

Killing freeze potential Friday night north of I-94

Broad surface high builds in the wake of the Thursday night's upper trough. Clearing skies and light winds after a period of post- frontal CAA will very likely (70-100%) lead to widespread frost, potentially (30%+) a freeze and, for areas north of I-94, a chance (20-50%) for a killing freeze with temperatures below 28. With some guidance suggesting some surface pressure gradient and thus light winds will be maintained Friday night will need to continue to monitor this period as there is still some uncertainty with regards to temperatures ending up a few degrees warmer than currently forecast.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1238 PM CDT Mon Oct 12 2026

Southerly winds continue into this evening ahead of an approaching area of low pressure. A few scattered showers and some rumbles of thunder are possible north of I-94 later this afternoon and this evening (20-40%) as this low pressure moves through the region. A short period of LLWS is also possible for valley sites across southwest Wisconsin tonight before a cold front moves through the region, veering winds to the northwest between 02z-09z. LLWS impacts are not expected at the TAF sites. MVFR to IFR ceilings are expected to move into the region behind the cold front as the 12.12z REFS/HREF depict fairly high probabilities (50-80%) for ceilings below 3kft through Tuesday morning, mainly for those outside of southwest Wisconsin, before lifting towards the end of the TAF period.

CLIMATE

Issued at 147 PM CDT Mon Oct 12 2026

Temperatures early this morning remained warmer than previous record warm lows for October 12th at Rochester and La Crosse. Thus, unless they fall quickly this evening before midnight, new records will be set. Here is where things stand after this morning:

La Crosse, WI (Record/Forecast High or Observed Morning Low):

Date High Temperature Warm Low Temperature ----- --------------- --------------- 10/12 87F (1995) / 87F 65F (1896) / 68F

Rochester, MN (Record/Observed so Far Today):

Date High Temperature Warm Low Temperature ----- --------------- --------------- 10/12 85F (1975) / 86F 61F (2008) / 63F

ARX WATCHES/WARNINGS/ADVISORIES

WI...None. MN...None. IA...None.