textproduct: La Crosse

KEY MESSAGES

- Frost development is possible early this morning with dry and mild conditions through the day as highs get into the low to mid 70s.

- Widespread shower and storm chances (30 to 70%) return this evening into the overnight. Periodic shower and storm chances continue through much of next week with some strong to severe storm potential on Sunday and Monday.

- Temperatures across much of the forecast area warm up into the 80s for the weekend and into early next week.

DISCUSSION

Issued at 1153 PM CDT Wed May 13 2026

Today-Mid Next Week: Periodic Shower and Storm Potential and Warmer

A brief stint of shortwave ridging moves over the area today. With mostly northwest flow aloft and low level winds just beginning to shift more southerly today, conditions remain dry and mild with highs in the low to mid 70s. As the afternoon progresses, a shortwave trough dips down into the Upper Midwest. CAMs continue to show a line of showers that moves through the CWA. A few rumbles of thunder will also be possible as there is a few hundred joules of MUCAPE. Cloud bases will mostly range from 5kft to 7kft as there is a bit of dry air in the sub-cloud layer. Some gusty winds may be possible with these showers as winds near the LCL height are between 25 and 35kts and these winds could make it down to the surface. With how dry the sub-cloud layer is and how fast this wave through, not much is expected rainfall wise, just a few hundredths with some locations potentially getting closer to 0.1".

From Friday through at least mid week next week, zonal to southwest flow aloft returns. This will bring about warmer temperatures and periodic chances at showers and storms. By Friday afternoon and evening, there is a good push of theta-e advection into western Wisconsin. This along with the a weak cold front, a few impulses of energy, and weak moisture transport bring about another round of showers and storms for Friday evening into the overnight. Precipitation chances (20 to 40%) continue, especially for areas along and south of I-90 during the day on Saturday as a stationary boundary sets up over northeast Iowa and northern Illinois.

Focusing our attention to Sunday and Monday, a shortwave trough ejects out of the central Plains on Sunday morning and pushes its way through the Upper Midwest. The warm front moves through the CWA during the afternoon and evening. There remains a bit of uncertainty on how far north this front can get, which will have a role in what areas see the better chance at severe weather. Some of the guidance has this warm front pushing even as far north as northern Wisconsin. There is quite of bit of shear and instability to work with (40 to 55kts of 0-6km for wind shear) although most of this shear is in the lower levels and SBCAPE of 1500 to 2500 J/kg. AI NWP and CSU-ML guidance highlights much of the forecast area in severe weather potential for Sunday.

The severe potential on Monday is dependent on what happens on Sunday. The main longwave trough shifts eastward across the northern CONUS becoming negatively tilted as it does so. This will send a cold front through the region. Similar to Sunday, there remains some uncertainty on when this front moves through. Currently, the deterministic GFS has the quickest evolution of the cold front, making it pass through the forecast area during the morning and mid afternoon, whereas much of the other guidance, such as the GEFS, CMCE, ECMWF, all have favor the front moving through a little later. If the front moves through a little later, then this would increase the severe potential across the CWA as there is a 40 to 60 kt 500mb jet streak over the Upper Midwest and into the central Plains which should help to increase deep layer shear as well as 1500 to 2500 J/kg of MUCAPE to bring around enough instability to create storms. With severe weather potential increasing for Sunday and Monday, be sure to check back for future forecasts to see how early next week trends.

There is also a heavy rain potential with these systems early next week. PWATs climb into the 1.25 to 1.75" range and there is a good amount of moisture transport that comes up with the strong southwest flow. Looking at the LREF probability for at least 0.5" falling in a 24 hour period, there is a 30 to 50% chance for both Sunday and Monday. There is also a footprint for over an inch (10 to 25%) for both days across the CWA. With the southwest flow, temperatures rise into the mid to upper 80s for Friday and again on Monday. The weekend will be slightly cooler with temperatures mainly in the upper 70s to low 80s.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 639 PM CDT Wed May 13 2026

VFR conditions through the TAF period. Mostly clear skies continue until Thursday morning when high level clouds between 20kft and 25kft move into the region. CIGS lower during the afternoon and evening ahead of a band of showers and storms. North to northeast winds early this evening shift to southeast winds for the overnight. Southerly winds pick up Thursday morning and afternoon, especially for areas along and west of the Mississippi River where sustained winds of 15 to 20 mph will be possible with gusts between 25 and 30 mph.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Frost Advisory until 7 AM CDT Thursday for WIZ017-029-034- 042>044. MN...None. IA...None.