textproduct: La Crosse

KEY MESSAGES

- Low potential for light rainfall this afternoon/evening and again late Saturday, but mostly dry conditions continue through Sunday.

- Greater rainfall potential exists Monday into Tuesday (40-70%) though the heaviest rain amounts look to stay northwest of the area. Additional potential exists mid next week.

- Temperatures trend cooler next week, but look to remain above normal.

DISCUSSION

Issued at 100 PM CDT Fri Oct 23 2026

This Afternoon - Sunday: Mostly Dry, Low Precipitation Potential

Primarily dry conditions continue throughout the rest of this afternoon and through much of the weekend as upper level ridging slowly shifts eastward. However, an area of shortwave energy reflected at 700-500hPa currently over the north-central Iowa/south- central Minnesota is expected to continue lifting northward along the western side of the ridge this afternoon into the evening. 700- 500hPa positive vorticity advection and 700hPa frontogenesis associated with this shortwave trough combined with some modest mid to upper level moisture advection may result in scattered sprinkles to light showers this afternoon. Not expecting much in the way of impacts, if we even see rain at the surface at all, as dry air below 10kft depicted in RRFS/RAP/HRRR soundings acts to evaporate the bulk of any rain as it falls. However, there have been observations of light rain associated with these forcings upstream so a few hundreths of rain does not appear unreasonable.

While the shortwave trough continues working its way across our area tonight, a strong upper level low moves eastward across Canada, dragging a cold front into the Upper Midwest by late Saturday. This feature stalls out across Minnesota into northern Wisconsin as it becomes separated from the upper level support, remaining somewhere north of I-90 into Sunday. Weak moisture advects along this boundary under southerly flow as various shortwave troughs eject northward from a cutoff low across the Desert Southwest, promoting some low chances for light rain late Saturday through Sunday (10-20%).

Next Week: Greater Precipitation Potential, Trending Cooler

The stalled cold front begins to slowly sag southward late Sunday into early next week, allowing cooler air to filter into the region. There's still some uncertainty regarding what temperatures will ultimately be due to variations in how far south the boundary makes it and the influence from potential rainfall, but the 23.13z NBM mean suggests highs top out in the upper 50s to low 60s.

Late Sunday into Monday, the cutoff low over the Desert Southwest begins to move northward, prompting a surface low to develop across the Great Plains. The various ensemble suites (GEFS/EPS/GEPS) appear to be in a bit better agreement about how these features evolve early next week though there is still some variation regarding the track of these features.

Currently, the ECMWF/Canadian suites suggest these features take a more northern trajectory resulting in lower rainfall amounts across our area whereas the GFS takes a more southerly track, bringing greater rainfall amounts to the Mississippi River Valley. Tending towards an ECMWF/Canadian solution, so thinking that our western and northern counties will be the ones to see the bulk of any precipitation. Around half of the 23.00z LREF members favor this solution (40-50%), which is in agreement with the 23.13z NBM that suggests 40-70% probabilities for rainfall for these counties. Regardless, not expecting a washout by any means. Deterministic amounts range from 0.25-0.5 inches in the GFS/AIGFS and Euro/AIFS with some potential for amounts greater than 0.5 inches per the NBM, around 20-40%. However, given the favored northern track, the greatest potential for amounts higher than 0.5 inches exist across central into east-central Minnesota, out of our area.

Midweek, there's some modest agreement within the 23.00z LREF membership that a shortwave trough moves across the northern United States, phasing with a longwave trough across Canada. A surface low pressure system looks to develop across the Midwest in response to these features bringing some additional rainfall potential, currently a 20-40% chance per the 23.13z NBM, and possibly some breezy winds before high pressure and dry conditions return by late next week.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1225 PM CDT Fri Oct 23 2026

VFR conditions expected for the next 24 hours at the terminals. A band of light showers is moving east northeast through South Central Minnesota early this afternoon and is expected to impact the KRST terminal over the coming hours. Upstream observations show light rain with this activity so visibilities and CIGs should stay at or above VFR thresholds. Southerly winds will continue through the period with gusts expected through the afternoon at the KRST terminal. Gusts should taper off by this evening but sustained speeds will remain elevated between 8-15 kts before gusts return late tomorrow morning.

ARX WATCHES/WARNINGS/ADVISORIES

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