


Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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965 FXUS63 KARX 291655 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 1155 AM CDT Sun Jun 29 2025 .KEY MESSAGES... - A few showers and storms linger this morning with scattered thunderstorms (40-50% coverage) redeveloping in the afternoon and evening, some of which could near severe levels. - Additional threat for storms Monday and midweek, but confidence is low (20-30%) in the coverage and impacts from these storms. - Warm today with seasonal temperatures for the start of the week, slowly warming again towards the end of the week. && .DISCUSSION... Issued at 140 AM CDT Sun Jun 29 2025 Today/Tonight: Storm Details Ongoing linear convection across Minnesota is gradually winding down early this morning as it starts to shift out of favored deep shear regime, resulting in the storms becoming outflow dominant. Nevertheless, forecast profiles from the HRRR/RAP denote large values of MUCAPE overnight with relatively low inhibition values for parcels launched around 800 mb as far east as western Wisconsin. If the outflow boundary manages to break this cap, we could see renewed development and the potential for gusty winds and small hail, but complex hodographs limit the organization potential for any individual updraft. The outflow and convective debris left over from our overnight convection (surprise!) results in degraded confidence in how and where convective initiation unfolds later today. What constitutes a surface cold front (more of a broad wind shift vs. a true front) migrates towards the region this afternoon from the Dakotas. This front will be approaching the region towards the mid to late afternoon, with convection likely initiating both along the boundary and ahead of it in any leftover differential heating zones courtesy of our morning storms. This makes it very difficult to pin down the exact placement of convection at any given time, though upscale growth into some cell clusters is anticipated given the complex hodograph profiles. As the surface front finally moves through in the evening/overnight, we may see enough lift to keep some showers and storms going through the night, mainly south of I-90. The severe potential for this afternoon rests on robust but short-lived updrafts getting strong enough to support brief periods of low end severe wind (60 mph) or hail (around 1" in diameter). Despite MLCAPE values nearing 2000 J/kg, the aforementioned complex and compact hodographs will limit the longevity of the updrafts and result in storms quickly getting undercut by their own outflow. As we move through the evening and night, the severe threat wanes with the increasing in boundary layer stabilization. Upcoming Week: Periodic, Low Confidence Risk of Storms While there are multiple periods of storms in the forecast for the upcoming week, the overall pattern is much drier than what we saw last week. For Monday, a sharpening upper tropospheric trough digs south into Minnesota, with there being enough kinematic support and steepening low-level lapse rates to support at least some convection--though the strength of the cells remains in question given some signal for poorer mid- level lapse rates stunting the vertical growth of the updrafts. Tuesday should see a break in the storms as shortwave ridging passes through. For midweek and into the end of the week, northwesterly flow downstream of a meridional High Plains ridge results in low confidence chances for convection, the details of which are difficult to resolve at this range. After another warm day today, cooler air settles in for the start of the week and keeps temperatures near seasonal norms. As return flow increases for mid to late week, increasing lower tropospheric theta-e air will boost temperatures and dewpoints back into the warm and muggy realm. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1155 AM CDT Sun Jun 29 2025 CIGS: high/mid level cigs predominant through the forecast period. Even with convection cigs likely to be above 6kft per the suite of meso models. WX/vsby: filtered sunshine and then a cold front will need to work together to spark showers/storms this afternoon. Latest runs of the CAMS suggest this won`t occur until the front has shifted east of KRST. Will hedge bets and keep a brief PROB30 for thunder risk at KRST for early afternoon, with TSRA more likely for KLSE (tempo) from mid to late afternoon. WINDS: southerly swinging west/northwest with the passage of the front this afternoon/early evening. Some enhanced gustiness possible around any collapsing storm (25-30kts). && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Skow AVIATION.....Rieck