textproduct: La Crosse

KEY MESSAGES

- Frost potential continues looks low for tonight.

- Periodic showers and storms from Thursday night into Sunday morning. Currently not expecting any organized severe weather.

- Continuing to look likely that above- to well-above normal temperatures will develop across the region from Memorial Day into Wednesday.

DISCUSSION

Issued at 1241 PM CDT Wed May 20 2026

Tonight

A northern stream shortwave, currently over Nebraska and South Dakota, will east northeast through the Upper Mississippi River Valley tonight. BUFKIT soundings show that a broken to overcast mid- and high deck of clouds will move into the area tonight. Much of this moisture is located above 600 mb and there is very dry air in the sub-cloud layer. As a result, not anticipating any precipitation from this wave. During the evening, there is a deep-layer of light winds. As the wave moves through the area during the overnight, the nocturnal, low-level jet increases. This will result in the boundary layer staying well mixed. This will help to keep our temperatures tonight from bottoming out overnight. Low temperatures along and north of Interstate 94 will be in the mid- and upper 30s, and in the lower and mid-40s elsewhere. Finally, there will be large temperature and dew point separation. This will result in little frost development. Due to this, we did not issue a Frost Advisory for tonight.

Friday night through Sunday morning

There will be 2 northern stream shortwave troughs will moving through the Upper Mississippi River Valley during this time frame. The first will move through the region on Friday and Friday night and the second one will move through the region on Saturday night. These systems will bring periodic showers and storms. The instability ahead of both waves are not that strong. It is up to 250 J/kg for the first wave and up to 750 J/kg with the second wave. In addition, the 0-3 and 0-6 km shear is only up to 20 knots. As a result, not expecting organized severe weather.

Memorial Day through Wednesday

A 500 mb ridge will build across the area. These building heights will result in above- to well-above normal temperatures developing across the region. This will potentially result in temperatures exceeding the 85th percentile (mid- and upper 80s). One concern is whether the trough south and southwest of this upper level ridge will move northward into the area. If this was to occur, temperatures would be more in the 60s and 70s and there would be a threat for showers and storms.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1241 PM CDT Wed May 20 2026

VFR conditions are expected throughout the TAF period with sct to bkn high clouds expected this evening and into the daytime hours on Thursday. Winds will shift from northerly to east-southeasterly at overnight and into the daytime on Thursday, increasing to around 6- 12 kts by late morning.

ARX WATCHES/WARNINGS/ADVISORIES

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