textproduct: La Crosse

KEY MESSAGES

- Scattered showers and storms west of the Mississippi River this afternoon and evening.

- Heavy rain possible Wednesday.

- Another potential heat wave next weekend.

DISCUSSION

Issued at 209 AM CDT Sun Jul 5 2026

Overnight

A shortwave trough will move south southeast through the area tonight. This trough is currently producing a line of showers and storms. This line will gradually wane as the surface-based and mixed- layer CAPES gradually decline and the outflow boundary surges ahead of it. We are already seeing this occur, and this trend will likely continue over the next 2 hours.

With all of the additional condensation nuclei (from fireworks) trapped under the nocturnal inversion overnight, there will likely be some valley fog. We are already seeing 2-3 mile fog at La Crosse. With the light winds and seeing fog already, we will likely see some dense fog this morning. At La Crosse, it will likely dissipate by 05.14z.

This Afternoon and Evening

The models are showing 0-1 km mixed-layer CAPES up to 1500 J/kg this afternoon and evening. There is a weak surface convergence ahead of yet another shortwave trough moving out of the Dakotas. This might result in some scattered showers and storms this afternoon and early evening. The better chances (20-40%) will be west of the Mississippi River.

High temperatures will be in the lower and mid-80s.

Tuesday into Wednesday night

The 500 mb flow will become zonal across the northern US. There looks to be several shortwave trough embedded in this flow. This will bring periodic shower and storm chances to the area. On Wednesday, a cold front will move slowly southeast through the area. This will allow precipitable water values to climb into the 2.25 to 2.5 inch range to pool along this front. In addition, warm cloud layer depths will climb to around 4 km. This will result in the potential for heavy rain. The is a slight risk for excessive rain across the northern half of Wisconsin and a marginal risk across the remainder of the area. As far as severe weather chances, the models are showing quite a bit of variance on the amount of 0-3 km and 0-6 km shear. As a result, there is much uncertainty om whether there will be any organized severe weather.

High temperatures will be in mid-80s on Tuesday and in the 80s on Wednesday. Low temperatures on Tuesday and Wednesday nights will be in the mid- and upper 60s.

Friday into Next Weekend

The models are in general agreement that the high will retrograde to the 4 Corners Region and heights will dramatically climb to around 600 decameters. Over time, this ridge will build north and northeast into the Northern Plains and Upper Mississippi River Valley. Like this past week, there will be thunderstorm complexes on the periphery of this ridge. The main question at this time is whether they will move across our area or stay to our north and northeast. This will also impact our temperatures too. The current forecast is for high temperatures in the lower and mid-80s. They could climb into the lower and mid-90s.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 600 AM CDT Sun Jul 5 2026

We currently have dense fog on the bluff tops overlooking La Crosse. KLSE has scattered 1K clouds. Confidence was not high, so added a tempo group of 3sm BR and a ceiling of 1K through 05.14z at KLSE. I did something similar to KRST too.

Afternoon and early evening instability showers and storms may impact KRST. Confidence was not high enough to include them in the TAF at this time.

ARX WATCHES/WARNINGS/ADVISORIES

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