textproduct: La Crosse

KEY MESSAGES

- Very low (<20%) rain chance Thursday.

- Rain nearly certain (99%) for Friday morning. A chance for thunderstorms for Friday evening, with some of these potentially severe. There is a 40 to 70% chance for at least 1" of rain to fall Friday into Saturday.

DISCUSSION

Issued at 1208 AM CST Thu Mar 5 2026

Very low potential for rain Thursday in northeast Iowa and southwest Wisconsin

Wave currently over NE KS rolls east-northeastward toward northern IN bringing an area of showers, currently developing in NW MO, with it. Slow trend across the past 4 runs of guidance, continuing into the 05.00z GFS/NAM, has been for a slightly farther south trajectory, keeping rain largely out of our forecast area. Given this and CAM output, have cut mentions of precip across all but portions of Grant/Clayton Counties.

Rain nearly certain Friday morning, potential for severe storms in the evening

Large western trough breaks eastward over the Plains Friday with an associate surface low developing in eastern CO and quickly moving northeastward to Lake Superior. Lead disturbance in the southwesterly flow aloft looks to eject downstream over the CWA during the morning hours. With multiple days of southerly moist advection occurring ahead of this feature, widespread rain will almost certainly (99%) result. Localized rain rates may be high, particularly for early March, as progged PWAT values upward of 1" are near the top end of climatology. Final amounts across Friday and early Saturday will be around 0.5-0.9" per 05.00z REFS mean values with an decent (40-70%) chance to reach 1" and a small (10%) chance for localized spots to approach 2" should a thunderstorm track overhead. Some rises on creeks and streams will occur as, while warm temperatures continue Thursday and Friday, significant frost depth remains in many locations and our recent snow bands have left a good chunk of the area not completely without snowpack yet.

As for the thunderstorm potential, more signs are starting to point toward most of the forecast area being in the warm sector during the late afternoon and evening as the aforementioned surface low races northeastward. Cluster analysis of older data (04.12z LREF) had about 47% of members with the warm front north of our CWA while the remaining 53% had this about halfway through the CWA. Reflecting this trend, 05.00z NAM has a noticeable shift northward from its previous solution which only had Fayette/Clayton/Grant Counties south of the warm front during the late afternoon and early evening. Given these trends in parameterized guidance and output from the 05.00z REFS/HREF, thinking thunderstorms are an increasingly good bet (50% for now). Should thunderstorms occur, strong southwesterly winds aloft combined with the southerly winds at the surface favors greater than 50 knots of deep layer shear. With cold temperatures aloft typical of March, this could lead to some severe hail if storms develop. Additionally, while an outside possibility (<10%) at this time given expected sky cover and morning showers delaying if not outright preventing surface destabilization, if storms can become surface based, a tornado risk would be present given sfc-500m SRH values upward of 150 m2/s2.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 523 AM CST Thu Mar 5 2026

IFR to low-VFR conditions are expected to begin the TAF period with a combination of low-level stratus and patchy fog being present across the local area. While vsby reductions are expected to improve by mid-morning as shallow low-level mixing occurs after daybreak, a low-level inversion aloft should keep low-level moisture in place with the HREF/NBH having high probabilities (60-90%) for MVFR cigs throughout the daytime hours. As our next weather disturbance moves into the region, cigs will likely drop to IFR heights with showers and embedded storms moving into portions of southeast MN and northeast IA by around 09z Friday. Consequently, expecting vsbys to drop to MVFR/IFR levels within showers and thunderstorms.

ARX WATCHES/WARNINGS/ADVISORIES

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