textproduct: La Crosse

KEY MESSAGES

- Much warmer temperatures beginning on Sunday and into the upcoming work week with highs in the 70s and 80s for many. Overnight lows may challenge daily warm low records with lows in the 50s to lower 60s on Monday and Tuesday.

- Active pattern from today through Tuesday with periods of showers and storms. There is some potential for severe storms during this period with Monday and Tuesday currently posing the greatest risk.

- Showers and storms chances persist through the end of the upcoming work week.

DISCUSSION

Issued at 1233 PM CDT Sat Apr 11 2026

Rest of Today - Sunday: Trending Warmer with Showers and Storms

An axis of showers and embedded storms will move through the region today and into the evening/overnight hours as a weak axis of 700mb warm advection moves through the region. Overall this is within a broader area of upper-level ridging which will allow our temperatures to steadily trend warmer over the weekend. The environment for any storms that develop in the area this evening and into the overnight is fairly unimpressive from a severe perspective as any convection will be forming atop a profound warm nose with MUCAPE values in the RAP of only around 500-1000 J/kg, mainly west of the Mississippi River. However with mid- level lapse rates approaching 7 C/km near I-35, would not rule out some small hail with the stronger updrafts.

As we head into Sunday, noticeably warmer temperatures will be on tap with southerly surface flow ushering in a much warmer and moisture rich airmass. As a result, the NBM inter-quartile range for highs on Sunday ranges anywhere from the lower 70s to around 80. As this occurs, this warm airmass pushes far to the north with much of ensemble guidance bringing highs near the 70 degree mark all the way up to Lake Superior! However, as we head into the evening and overnight, an enhancing axis of 850mb moisture transport will push north on the nose of a increasing nocturnal low-level jet. As this moisture transport axis pushes north not only will it be an instigating mechanism for showers and storms but will bring some fairly respectable instability (1000-1500 J/kg of MUCAPE) north with it across portions of southeast MN and into north-central WI. Large hail would appear to be the primary hazard still in this environment with mid-level lapse rates of around 7 C/km, however could see some damaging wind gusts with decent DCAPE in the RAP to around 1000 J/kg in the aforementioned region with robust dry air entrainment possible with any convection that gets going. Also cannot rule out a weak tornado in north-central WI as this low-level jet interacts with the surface boundary overnight, however this would seem pretty unlikely given the lack of deep-layer shear. Overall though with relatively weak flow in the mid-levels, this would not favor very organized convection so this would likely keep the severe threat more localized in nature.

Monday - Tuesday: Severe Potential Both Monday & Tuesday

The severe potential ramps up slightly into Monday and Tuesday as we enter a fairly progressive synoptic pattern with various shortwave perturbations and surface low pressure features that push northwest of the local area. As we head into Monday the warm airmass that we were pushed into on Sunday remains with highs likely yet again reaching into the 70s and 80s. Additionally, with dewpoints reaching into the 50s and lower 60s on Monday morning, morning lows on Monday may only be in the 50s to lower 60s as well. These higher dewpoints as a result of Sunday night's moisture advection will lay the groundwork for some severe potential as temperatures heat into the afternoon with increasing instability. As we head into the evening, a surface low will pass northwest of the local area dragging the warm front northward with a sfc boundary draped to its south. As a result, could see a first round of convective initiation during the late afternoon as the warm front pushes northward through the local area, primarily near and north of I-90. In this environment, soundings in the RAP note fairly robust capping in the warm sector which would mitigate a tornado threat, however with fairly robust instability (around 2000 J/kg in the NAM) atop the warm nose and mid- level lapse rates approaching 8 C/km, would think that there would be a fairly robust hail threat with any convection that gets going during this period.

Now things get a bit more challenging later into the evening as the surface low pulls northward and swings the aforementioned sfc boundary east into the local area late Monday evening and into the overnight. As this occurs, there is some tendency in the deterministic models NAM/GFS/RRFS for thermodynamic profiles to gravitate to more surface-based with this being coupled with an increasing low-level jet resulting in 0-1km SRH values sharply increasing to around 200-300 m2/s2. As a result, if any convection can get going along this boundary into the overnight, this may pose a tornado risk IF surface based convection can be realized. Still not exactly clear if the warm nose can be cooled enough to allow for surface based storms though. In any case, this period is probably the lowest confidence period for severe potential at this juncture in the forecast process.

The active pattern persists into Tuesday though with additional severe potential on the table. Overall confidence in seeing strong to severe storms in the warm sector is higher for Tuesday given the general agreement for more surface based instability in the GFS/NAM. However, the key question is exactly how far north this warm sector reaches into the local area during the afternoon hours. Generally speaking, the GEFS/GEPS has fairly high probabilities (50-90% chance) for over 1000 J/kg of SBCAPE for areas near and south of I- 90 on Tuesday afternoon so would think that areas generally near and south of I-90 would be most likely to have ample surface-based instability for convection with the highest confidence being in portions of southwest WI and northeast IA. Decent hodograph elongation would favor supercells in this environment with all hazards being in play.

In addition to the severe potential, will have to see where each round of storms lines up as there is some heavy rain potential as well given that we may see several rounds of showers storms through Tuesday. Overall, the NBM 72-hr QPF inter-quartile spread has a general 1-2" of rainfall across the area from Sunday through Tuesday. However, the 90th percentile has spots approaching 3"+, likely where storms repeat over the same locations. As a result, does not currently appear to be a widespread flooding setup but localized spots that receive higher amounts may see some rises on area rivers.

In summary, strong to severe storms possible late Monday afternoon and continuing into the overnight with large hail and a conditional tornado threat later into the evening. On Tuesday, confidence is higher for storms that develop to be strong to severe but questions remain on exactly how far north into the local area the threat extends with all hazards possible. In any case, will need to watch to see where storms track as storms that frequent the same areas may result in rises on rivers in those respective basins.

Wednesday - Friday: Shower and Storm Chances Persist

As we head into the middle of the upcoming work week, rain chances likely persist however with the higher probabilities (0-30% locally) for dewpoints over 55 degrees remaining south of the local area on Wednesday and Thursday, think that this should lessen the severe weather potential. Additionally, probabilities for rainfall amounts over 0.25" are not overly high (20-50%) on Wednesday and Thursday. The overall pattern becomes a bit more active into Friday though as a secondary trough out west begins to eject eastward towards the region. As a result, Friday could see an additional round of storms with joint probabilities for 500 J/kg of SBCAPE and 30 kts of bulk shear in the grand ensemble (GEFS/EC/Canadian ensemble) increasing to around 30 to 50 percent. Regardless of any severe potential, the NBM has decent probabilities (40-50%) for rainfall amounts of over 0.5" on Friday as well.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1254 PM CDT Sat Apr 11 2026

Increasing moisture should lead to both periodic showers through the period and an eventual reduction in ceilings to MVFR and even IFR over the next 6-12 hours. Uncertainty surrounds exact timing of showers and if any thunderstorms will occur. Latest trends suggest TS will struggle mightily to develop until late tonight when a low level jet ramps up - have handled the possiblity with targeted PROB30 groups rather than prevailing TS. This jet should also lead to low level turbulence but, without much change in direction over the lowest 2 kft, have left LLWS mentions out of the TAF.

CLIMATE

Issued at 1233 PM CDT Sat Apr 11 2026

Potential Record Warmth Monday & Tuesday (Record/Forecast):

April 13th High Temp Warm Low ----------- -------- ------- Rochester, MN 83 (2023) / 75 59 (1941) / 57 La Crosse, WI 85 (2023) / 78 63 (1941) / 59

April 14th ---------- Rochester, MN 87 (2003) / 76 56 (1976) / 56 La Crosse, WI 90 (2003) / 78 60 (1883) / 58

ARX WATCHES/WARNINGS/ADVISORIES

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