textproduct: La Crosse

KEY MESSAGES

- Severe storm chances continue through this morning with the primary hazards being damaging wind gusts and large hail.

- Dangerously hot conditions are expected once again this afternoon with heat index values approaching 110. These hot temperatures can cause heat related illnesses.

DISCUSSION

Issued at 1242 AM CDT Mon Jul 27 2026

Through This Morning: Uncertain Severe Storm Chances

Multiple clusters of showers and storms continue to develop from southeastern Manitoba to north central Wisconsin at the time of this writing. Even though the environment is conducive for severe storms to form with plenty of instability and shear, the upper level ridge is keeping the convection mostly suppressed so far throughout this event. Mid level capping continues to win out even though a few storms so far this evening in northeastern Minnesota have shown signs of tapping into the better environment, but they have not lasted long. Upper level lift, which is currently located over northeastern ND into Manitoba, should continue to round the ridge and develop storms over northern Minnesota. Those storms should move southeast into Wisconsin going into this morning.

There continues to be tremendous uncertainty regarding timing, location, and severity of storms tonight into Monday morning. The hi-res forecast models continue to have no run-to-run consistency and all offer differing solutions. Based on recent observational trends and satellite interpretation, the current expectation is leaning towards a later start to any potential severe storms, potentially not impacting the forecast area until sunrise or later on this morning. If that scenario ends up panning out, the potential is there for a damaging wind gust event across portions of Wisconsin and further east, especially if any sort of daytime heating can occur before storms reach the region leading to lesser CIN. Large hail would also be possible but a lesser concern as the storms are expected to form along a line. Another potential scenario is that the storms or line of storms completely misses the FA to the northeast and east if the axis of the ridge is too far northeast across the area, which would direct storms around the CWA. There are even further solutions that suggest the storms that are currently ongoing will be able to form into severe storms in the next few hours. That scenario currently has the lowest confidence in panning out based on observational trends with the other two scenarios having equal confidence in occurring, even though that confidence remains very low right now.

Additional development may occur as the shortwave along with a surface boundary move across the region this morning. Model guidance shows the front moving across during the morning hours and where ever the front interacts with a potential line of storms or any outflow boundaries, that could be enough to quickly generate storms. Where or if any interaction occurs remains very low in confidence. To summarize this all, confidence in any severe storms and their timing or location, is very low but the environment will remain highly conducive for severe storm development through this morning.

Rest of Today: Dangerous Heat and Additional Storm Chances

Confidence in the dangerous heat has also decreased due to the later push of potential storms along with cloud cover. Plentiful surface moisture is expected to remain in place to lead to high heat index values if sufficient daytime heating can occur, which could lead to heat index values of 100 or higher. The potential for morning fog combined with cloud cover and potential convection has led to uncertainty in the highest afternoon temperatures at this time. The previous heat headlines remain in place given the high potential still for heat index values to reach or exceed 100 across most of the area. With how much moisture is in place, a few isolated afternoon storms may try to form but confidence in that remains quite low.

Tuesday into Next Weekend: Warm Temperatures and Storm Chances

The ridge shifts westward just enough and northwest flow remains in place mid week. Both of these will mean temperatures cool down marginally, into the mid to upper 80s along with lower heat index values. The potential for heat index values to reach or exceed the triple digit mark is low Tuesday and beyond. With this flow pattern, ensemble guidance has low precipitation chances through midweek with better chances as we head towards the weekend. The ridge is expected to become suppressed far enough south for stronger troughs to push across the Northern Plains into the Midwest which should trigger a few rounds of rain potential at the end of this week into the weekend.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1242 AM CDT Mon Jul 27 2026

Somewhat of a challenging forecast tonight as models struggle to handle ongoing showers and storms over northern Wisconsin/northeast Minnesota. Thinking that said showers and storms will largely remain north and east of the region through much of the overnight before coverage increases after 10-12z. Because these showers/storms have stayed to the northeast, patchy fog is expected to and has begun to develop, resulting in visibility restrictions to some sites including KRST. Lots of uncertainty remains in how showers/storms will evolve after that 10-12z timeframe, leading to a low confidence forecast through at least mid-day. Areas east of the Mississippi River are most likely to see showers and storms though, highlighted by the 27.00z REFS/HREF which suggest a 20-40% chance of precipitation.

Confidence in the forecast increases this afternoon into tonight. A surface front is expected to move through the region, shifting tonight's southerly winds to the northwest along with some gusts to around 20KT. Near surface smoke also looks to be on the rise along the front, though not to the extent of last week. Have included some mention of slightly reduced visibilities to account for the smoke, but visibilities improve with time tonight as smoke clears out behind the front.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Extreme Heat Warning until 9 PM CDT this evening for WIZ041- 042-053>055-061. Heat Advisory until 9 PM CDT this evening for WIZ032>034-043- 044. MN...Extreme Heat Warning until 9 PM CDT this evening for MNZ096. Heat Advisory until 9 PM CDT this evening for MNZ079-086>088- 094-095. IA...Extreme Heat Warning until 9 PM CDT this evening for IAZ008>011-018-019-029-030.