textproduct: La Crosse

KEY MESSAGES

- Frost this morning across north-central and central WI. Typical cold spots in central Wisconsin may fall below the freezing mark this morning.

- Outside of low, light chances tonight in central Wisconsin, precipitation free conditions expected throughout most of the week.

- Near to slightly above normal temperatures throughout much of the week with highs in the 60s to lower 70s. Tuesday will likely be the warmest day with highs in the 70s areawide.

DISCUSSION

Issued at 217 AM CDT Mon Oct 5 2026

This Morning: Frost in North/West-Central Wisconsin

Temperatures are cooling fairly rapidly in cold drainage locations of central WI tonight with Black River Falls, WI observing a temperature of 38F just before midnight. With limited sky cover and calm winds overhead, thinking that temperatures in cold drainage locations in Jackson, Monroe, Juneau and Adams counties will likely plummet quickly overnight. Based on current observations, would seem fairly likely some spots will hit or fall below the freezing mark in these counties. Elsewhere in the Frost Advisory, scattered cloud cover further north may hinder some radiational cooling in Clark and Taylor counties, however thinking that temperatures should get cool enough for frost formation near daybreak.

This Afternoon - Friday: Dry and Slightly Above Normal Temperatures

Synoptic scale northwesterly flow remains the primary synoptic flow throughout this week that will drive much of how conditions will pan out through Friday. Overall, expecting a slight warming trend into Tuesday as shortwave ridging pushes north of the region with low- level southerly flow in place. Consequently, temperatures will likely warm into the 70s for much of the local area as seen in median temperatures in the NBM. However, given the synoptic setup and decent mixing with steep hydro-lapse rates atop the mixed layer, thinking that temperatures will likely overachieve as we work drier air to the surface on Tuesday. Therefore, have decided to nudge high temperatures closer to the 90th percentile of the NBM for Tuesday afternoon with highs in the middle 70s. In any case, this ridging slides eastward in the northwesterly flow which in turn returns flow back to west/northwesterly through Friday and thus keeps temperatures closer to normal with highs generally in the 60s to lower 70s. With the lack of any appreciable shortwave energy moving through the northwesterly flow throughout the upcoming week, thinking any precipitation potential is very low which is seconded by the grand ensemble (GEFS/EC/Canadian ensemble) keeping measurable precipitation probabilities very low (0-20% chance) through Friday.

This Weekend: Trending Dry and Warm

As we head into the weekend, guidance generally agrees on pushing some broader upper-level ridging into the region and turning flow more zonal aloft. This in addition to increasing southerly low-level flow will aid in advecting a warmer airmass into the region for the weekend. Consequently, the NBM has fairly respectable probabilities (30-70%) for seeing high temperatures over 75 degrees this weekend, primarily on Sunday as the ridge moves overhead. Additionally, ensemble guidance generally agrees on keeping measurable precipitation chances to a minimum (10-30%) over the weekend with the grand ensemble (GEFS/EC/Canadian ensemble). However, noting some geopotential height falls in deterministic guidance by Sunday and into early next week as a large scale trough attempts to eject into the Great Plains which could increase precipitation chances, but predictability remains very low during this time period.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 639 AM CDT Mon Oct 5 2026

Some area valleys have have developed fog overnight, including the the Mississippi River Valley which has resulted in IFR/LIFR impacts at KLSE. However, low level winds >10KT at 2kft have resulted in the fog within the Mississippi Valley being more patchy and moreso reflected as low stratus, so these impacts to KLSE will be intermittent through the next hour or two. Otherwise, fog/low stratus dissipate between 13-14z with VFR conditions and southerly winds around 5-10KT taking over this afternoon. Apart from some light shower potential north of I-94 tonight (20-30%), these conditions are expected to prevail through the rest of the TAF period.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Frost Advisory until 9 AM CDT this morning for WIZ017-029-034- 042>044. MN...None. IA...None.