textproduct: La Crosse

KEY MESSAGES

- Storm chances Sunday, Monday, and Tuesday. Besides heavy rain causing river and areal flooding concerns, should severe storms form primary concerns of large hail and damaging winds each day.

DISCUSSION

Issued at 1129 PM CDT Sat Apr 11 2026

Sunday Morning Storm Potential:

While scattered storms shift east of the forecast area overnight, much of the area is expected to wake up to additional storms as the low level jet, evident on upstream VWPs of 50kts at 850mb and 40kts at 925mb through the Central Plains, focuses on the Upper MIssissippi River Valley. A coincident weak mid level perturbation grazes slightly steeper mid level lapse rates towards the western reaches of the forecast area, initiating storms slightly upstream or over locally western counties in southeast Minnesota and northeast Iowa. As storms initiate off the excited low level jet, weaker mid level winds will cause undercutting of accompanying updrafts, keeping strongest storms along the nose of the low level jet. While stronger storms will be capable of hail and strong winds, overall lack of accompanying instability limits confidence in widespread, more intense strong to severe storms locally through the morning hours.

Subsequent Sunday Afternoon/Evening Storms:

Subsequent storm chances primarily highlighted across southeastern half of the forecast area through Sunday afternoon/evening by high resolution model simulated reflectivity solutions as low level convergence tightens within an additional low level trough passage. However, western extent of storm initiation will be important detail to remain cognizant of as ribbon of enhanced instability, 2000 J/kg+ SB CAPE (HRRR 26.00Z), grazes and advects into western reaches of the forecast area. While an elevated mixed layer is causing the lack widespread storm initiation in these counties, should sufficient forcing ahead of the associated dry punch initiate storms, shear values would support strong to severe storm potential farther west than forecasted for Sunday. Besides heavy rain, large hail and damaging winds would be the primary severe hazards as confidence in storms becoming surface based is limited. Available instability and subsequent strength of storms across southeastern half of the forecast area hinges on exit timing of morning storms.

Storm Chances Monday:

A shortwave ridge erodes much of the low level moisture Sunday night into early Monday morning before another amplifying wave advects a subsequent low level warm, moist sector across the forecast area. Current timing advects initial band of non- severe storms across the forecast area from isentropic upglide Monday morning. Lower confidence through the afternoon/evening as the initial glance into high resolution soundings show a stout 800mb-700mb EML with 15C+ dewpoint depressions quickly following initial low level moisture transport. Given the plethora of instability (1500-3000 J/kg) due to steep mid level lapse rates advecting over the forecast area and strong winds causing increased effectively available shear, severe storm threat persists. Although, an overall slowing trend to the trough limits confidence in accompanying forcing. Primary hazards of large hail and damaging winds in current forecast regime.

Storm Chances Tuesday:

Unfortunately, confidence for Tuesday decreases further as resultant frontal location and available instability both remain in question. Long LREF hodograph plumes with some spread in accompanying temperature soundings suggest severe probabilities could continue from initially splitting supercells should the warm sector remain present and the EML shunts off to the southeast. Eventual east-southeast progression of a frontal boundary would provide sufficient forcing for linear storms through the forecast area although exact diurnal timing is the forecast crux.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 649 PM CDT Sat Apr 11 2026

Less widespread precipitation at 12.00Z TAF issuance resulted in removal of previously forecasted accompanying visibility impacts. Backside of precipitation seen on radar entering Dodge County, MN to Floyd County, IA. Expect this clearing to advect through both TAF sites (KRST/KLSE) over the next few hours.

Storm chances increase from west to east through early Sunday morning although exact location remains in questions as overall extent expected to be /initially/ limited. Aviation impacts primarily expected across southeastern of the forecast area through Sunday night.

HYDROLOGY

Issued at 1129 PM CDT Sat Apr 11 2026

An anomalously moist airmass, record moisture values observed Saturday night at Chanhassen (SPC RAOB Climatology), lingers through start of the new week. Given overall confidence in exact daily storm location and accompanying impacts remains low, concerns for storms frequenting similar areas each day will require close monitoring for potential river flooding in large and small river basins given already slightly swollen river levels.

Current forecast confidence has maximum 24 hour QPF values nearing 2"+ where storms form. Current forecast timing unfortunately limits personal model availability.

CLIMATE

Issued at 1141 PM CDT Sat Apr 11 2026

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

April 13th High Temp Warm Low ----------- -------- ------- Rochester, MN 83 (2023) / 74 59 (1941) / 55 La Crosse, WI 85 (2023) / 76 63 (1941) / 59

April 14th ---------- Rochester, MN 87 (2003) / 72 56 (1976) / 55 La Crosse, WI 90 (2003) / 76 60 (1883) / 58

ARX WATCHES/WARNINGS/ADVISORIES

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