


Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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297 FXUS63 KARX 062350 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 650 PM CDT Sun Jul 6 2025 .KEY MESSAGES... - Small chance (20%) for pop-up showers this evening, mainly east of Mississippi River. - Additional small chances (20%) for afternoon pop-up showers and storms Monday afternoon. Heading into Monday night, a decaying line of storms with areas north of I-90 more likely to see rain (60% chance). - Unsettled pattern to end the week with 60-70% chance of showers and storms on Friday. && .DISCUSSION... Issued at 140 PM CDT Sun Jul 6 2025 This afternoon: Isolated pop-up showers, possibly a weak storm Recent convective allowing model runs have been showing a fairly consistent signal for isolated pop up convection this afternoon- evening. This will be mainly across portions of southwest/central Wisconsin where RAP analysis shows an axis of weak surface convergence - northeasterly flow over central/southern Wisconsin advancing into more northerly flow closer to the Mississippi River. Diminishing cloud cover and lingering elevated dewpoints have allowed for increasing instability with SBCAPE up to 1000 J/kg. Have introduced slight chance (20%) PoPs to account for isolated shower activity, but given the instability present can`t rule out a few rumbles of thunder with the activity. Things should diminish quickly this evening with the loss of daytime heating. Some patchy fog likely tonight given the abundant humidity. Monday-Monday night: Afternoon pop-up showers/storms, then a decaying line of convection Monday afternoon is looking to bring almost a repeat of today, with a building axis of daytime instability in the vicinity of the Mississippi River interacting with a weak inverted trough and resultant surface convergence. This should again favor some additional pop up showers and storms in the afternoon hours, so have added slight chance PoPs to much of the Mississippi River valley and surrounding areas. Heading into Monday night, a decaying linear MCS from the Dakotas will move into the area. Guidance show a wide variance in its arrival time with the RAP bringing it into our northwest after 8pm, the HRRR/ARW/FV3 all closer to 10pm, and the NAMNest not until after midnight. So, timing will need to be refined over the next 12-24 hours. But there is general agreement that the activity should weaken substantially, if not almost dissipate, as it approaches the forecast area. Here again, the NAMNest is an outlier as it retains a weakened but broken bowing line of storms through the area late night due to its comparably much higher dewpoints near 70. Given the wide spread, will stick with NBM PoPs for now (wide line of 50-60+%) but based on current diminishing trends would expect PoPs to have to be trimmed much further north where forcing is more favorable. Looks like higher chances north of I-90 and especially north of I-94. Not expecting anything strong from this activity. Rest of the week: seasonable with periodic storm chances An amplifying ridge upstream over the Rockies will put us in a northwest flow aloft pattern heading into midweek, setting us up for what looks to be more active weather beyond Wednesday. A couple shortwaves are progged to move through the region sometime in the Thursday-Friday period. NCAR AI and machine learning numerical weather prediction guidance depict the greatest likelihood of severe weather with these features over the Dakotas and western Minnesota on Day 5, so will be something to keep an eye on as we get closer in time. This looks to be followed by a closed upper low grazing our area on Saturday. All in all, looks like on and off rain chances to end the week. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 645 PM CDT Sun Jul 6 2025 VFR conditions are forecast for this evening prior to 06Z. While confidence is increasing that there will be some form of fog/low ceiling restrictions across much of the area between 06-15Z, the exact coverage and magnitude of these restrictions is much less certain. Have trended TAFs downward to IFR levels for a time near sunrise, but there is a 20-30% chance these fall to LIFR. Conditions quickly improve to VFR after 12-15Z. Winds will be light from the north tonight and from the south on Monday with an increasing risk of isolated showers and storms in the afternoon. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Kurz AVIATION...Skow