textproduct: La Crosse

KEY MESSAGES

- Cooler conditions persist through Friday with most locations remaining dry.

- Thunderstorm chances return this weekend into early next week with very low confidence in severe storms at this time.

- High heat index values of 100 or higher on Sunday and Monday could lead to heat related illnesses and a Heat Advisory may be needed for parts of the area on both of those days.

DISCUSSION

Issued at 345 AM CDT Thu Jul 23 2026

Through Friday: Below Average Temperatures and Mostly Dry Conditions

Mostly quiet weather continues through Friday as upper level high pressure continues to meander around the southern High Plains into the Desert Southwest. Northwest flow will remain over the forecast area during this time frame and temperatures will remain slightly below average in the 70s to lower 80s for highs. Mainly dry conditions are still expected for most of the area, however, a few rain showers or a storm may occur on Friday morning across northeastern Iowa. Just enough H700 theta-e may reach northeastern Iowa out ahead of a southeastward propagating shortwave to allow very light rain showers to reach portions of the CWA. The 23/00z suite of hi-res guidance is hinting at this potential, but given low confidence in that scenario panning out, have kept PoPs below 10 percent. If any rain does occur, it would likely only amount to a few hundredths at best.

This Weekend into Next Week: Storm Chances Return

Moisture throughout the column will continue to surge northward going into this weekend as the high pressure system to our southwest strengthens and the ridge elongates well into Alberta and Saskatchewan by Saturday. Shortwave troughs are expected to round the ridge axis this upcoming weekend providing chances for thunderstorms, some of which could be severe. However, model guidance continues to show strong capping around H800 on Saturday through Monday which does leave high uncertainty in the severe storm aspect for those days. Even with that being said, thunderstorm chances continue to trend up given the combination of increased moisture and PVA supplied by shortwaves moving over the region. Timing and location of any potential storms is also another area of uncertainty as model guidance does not agree with the timing and placement of some features.

Sunday and Monday: Summer Heat Returns with Potential Heat Headlines

The increase in surface moisture along with the strengthening of the ridge does come at a cost in terms of the hot conditions returning to the region. Low level WAA moves in this weekend but should be at its peak on Sunday and Monday with H850 temperatures in the lower to mid 20s Celsius. Model guidance yesterday was not too keen on heat index values approaching 100 on Monday, however, that has quickly changed over the last 24 hours. Now both Sunday and Monday are featuring at least 30-50 percent chances for heat index values to reach or exceed 100 based on the latest probabilities from long range ensembles. Northeastern IA and southeastern MN currently have the higher potential for heat related headlines on Sunday and that becomes more widespread into southwestern and west central WI on Monday. Cloud cover and potential shower or thunderstorm activity could lead to the air temperatures being a bit on the high side in the NBM but will refrain from making any changes at this point due to high uncertainty.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 602 AM CDT Thu Jul 23 2026

Outside of lingering River Valley fog in the Wisconsin and Mississippi River Valleys this morning, VFR expected through the rest of the 23.12Z TAF period.

ARX WATCHES/WARNINGS/ADVISORIES

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