015 FXUS63 KARX 052326 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 626 PM CDT Fri Jun 5 2026 .KEY MESSAGES... - Isolated to scattered storms late this afternoon thru early overnight. Confidence has increased for severe storms later this evening near and north of I-90. Large hail and strong wind gusts would be the main hazards with any severe storms. - Dry start to the weekend gives away to another round of rain on Sunday through Monday. - Trending hot for the middle and end of next week with highs likely in the 90s and heat indices approaching the 100 degree mark. && .DISCUSSION... Issued at 131 PM CDT Fri Jun 5 2026 This Afternoon - Early Overnight: Isolated to Scattered Storms, Some Strong to Severe A continued difficult forecast remains for this afternoon and into the evening hours for storm initiation. As has been stated in previous forecast discussions, the environment trends more favorable for organized convection later into the evening today, the key question is will there be enough lift to generate convective initiation as forcing mechanisms remain uncertain. But to take a step back, current satellite trends this morning have depicted a low-level cloud shield over the region which is generally expected to mix out to some extent this afternoon. As this occurs, surface destabilization will result in an increase in MLCAPE values to around 1000-1500 J/kg across the local area. With some degree of inconsistency where destabilization occurs, this will likely set up some differential heating boundaries during the afternoon which in turn may work as an axis to initiate convection. As a result, the CAMs generally agree on developing storms in the area later this afternoon and in the evening, with low confidence on exact location but the earliest timing likely being between 2-4pm. In this environment, storms may pose some hail and strong wind risk, however the weaker shear profiles initially would not make this a widespread concern. However, how convection evolves earlier in the afternoon will certainly impact how later storms may develop as they could work to both increase the amount of available outflow boundaries as well as work over the environment if convective initiation is more widespread. This will be important for later into the evening as a shortwave trough pushes into the area, working to cool our mid-levels slightly and increasing mid-level shear while elongating our hodographs. As a result, any storms that do develop in this environment (generally 6pm to 3am) would have a tendency to become more organized, possibly supercellular as shown in the HRRR. In this scenario, a hail threat would be on the table with supercell storms and 40-50 kts of 0-6km bulk shear to work with near and north of I-90 and mid-level lapse rates to around 6.5 C/km. Furthermore, with DCAPE values increasing during the late evening with some dry air entrainment would suggest some strong winds within these cells would be possible in addition to cold pool organization resulting in linear/bowing segments. So important to emphasize that there are a few scenarios here, much of the CAMs agree on some level of convection during the afternoon and evening in the local area but the severe threat is conditional on if storms can develop during the late evening period when shear profiles begin to become more favorable. However, it is becoming more likely that if storms do occur in the evening hours for areas north of I-90 where the shear profiles are more robust, they will become severe. As a result, SPC has upgraded these areas to a Slight Risk (Level 2 out of 5) for severe weather. Saturday - Monday: Dry Start to Weekend with Increasing Rain Chances As we head into Saturday, upper-level ridging will move into the area with subsidence underneath it keeping precipitation chances to a minimum. Additionally, with relatively clear skies underneath the ridge would expect temperatures to climb into the middle and upper 80s during this period. However, as we head later into Sunday and into Monday rain chances will begin to increase as a pronounced mid-level shortwave moves into the region in the southwesterly flow regime. As a result, precipitation chances increase fairly significantly during this period with the grand ensemble having fairly respectable probabilities (40-60%) for rainfall amounts of 0.5" into Monday. With fairly high dewpoints and moisture coming in, cannot rule out some heavier rainfall during this period as well. However, given the lack of strong flow aloft with this wave, organized severe convection seems unlikely with this system. Tuesday - Saturday: Trending Hotter As we head late into the week, an upper-level ridge will become situated over the local area resulting in southerly low-level flow across the local area. As this occurs, moisture advection will result in dewpoints increase fairly dramatically across the local area with the grand ensemble (GEFS/EC/Canadian ensemble) having high probabilities (70-90%) for dewpoints in the 70s. This coupled with highs approaching the 90s would suggest that we could see heat indices approaching the 100F mark. Some conflicting guidance between the bias-correction in the NBM and the raw models leads to some uncertainty in exactly how warm we will get. But given the EC Extreme Forecast Index has a fairly strong probability footprint (70-90%) for temperatures to exceed model climatology, thinking temperatures will be fairly above normal, just a matter of how much above normal and if any finer details such as precipitation potential would keep us cooler. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 626 PM CDT Fri Jun 5 2026 Main taf concern is the potential for thunder at both taf sites early in the taf period. Weak cold front slowly moves over the area this evening and has been the focus for showers and isolated storms over western Wisconsin/central Minnesota this evening. Instability is not great over the area this evening and weakens after 03z Saturday. Coverage of storms is expected to be isolated across the area. For now...have introduced showers into the taf sites between 02-04z Saturday and a tempo group for an isolated storm at both RST/LSE taf sites. After showers pass the taf sites...the next concern is potential for fog formation across the region. With residual cloud cover from the showers not sure if area will clear out. However...low level moisture and weak inversion could develop fog over the area after 06z Saturday. At this time will leave mention out of tafs based on confidence is low. After 14z Saturday...VFR conditions should prevail at both RST/LSE taf sites. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Naylor AVIATION...DTJ