FXUS63 KARX 270504 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 1204 AM CDT Mon Oct 27 2025 .KEY MESSAGES... - Dry and warm start to the new week with highs touching the upper 50s to around 60 on Monday. - Increasing clouds and rain Tuesday through Wednesday morning. Highest rainfall amounts along and west of the Mississippi River where there is a 40-60% chance of seeing over 1/2 of an inch. - Temperatures slowly cool through the week with highs in the low 50s to end the week. && .DISCUSSION... Issued at 150 PM CDT Sun Oct 26 2025 Dry and Warm into Monday Split flow over the region allowed for clearing skies and ample sunshine this afternoon, allowing for temperatures to rise into the upper 50s to around 60. The general ridging pattern does not fully shift out of the region until midday Monday, keeping pleasant weather (highs nearing 60 in spots) on the docket to start the week. Rain Showers for Monday Night - Wednesday Morning Negatively-tilted longwave troughing expands eastward from the High Plains late Monday into Tuesday with a broad surface baroclinic zone/lower tropospheric isentropic ascent sliding east of the Siouxland region Monday night. This frontal zone stalls near the I-35 corridor and pivots for Tuesday/Tuesday night as a Red River Valley low lifts north and a Ohio River Valley low takes over shortly thereafter. While the synoptic pattern is coming into clearer focus, there remains modest uncertainty in just how far east this frontal boundary advances before it stalls. This will dictate the eastward extent of the rain shield over western Wisconsin with there being some indications in the deterministic members of a sharp cutoff in rainfall amounts from west to east. Along and west of the Mississippi River, there is high confidence (>80%) in there being rain with an axis of heavier rainfall likely (50-70%) between I-35 and the Mississippi River. A look at the individual ensemble members shows that it is a matter of where, not if, this axis of higher rainfall amounts develops with many members printing out between 0.5 to 1 inch of rain within this corridor. Given the spread in the QPF guidance, the mean LREF 1-inch rainfall probabilities are skewed lower than one might expect (10-20%), but 1 inch of rain is a realistic possibility for a few locales west of the Mississippi River. These rainfall amounts are mainly driven by the long duration of the precipitation over 24-36 hours versus high rainfall rates, thus localized flooding impacts are not expected. The rain and clouds on Tuesday will cool off temperatures 5 to 10 degrees compared to Monday. Areas west of the Mississippi River may be stuck in the 40s all day (50-70% chance). Outlook for the Rest of the Week A progressive northwesterly flow pattern sets up for the end of the week, mainly dominated by decaying ridges interspersed with a few vort lobes/troughs. Overall rainfall impacts look quite low in this setup, but can't fully rule out a light shower from late Thursday into the weekend. The northwesterly flow will steadily cool temperatures to near or slightly below seasonal norms with highs in the low 50s to end the week. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1204 AM CDT Mon Oct 27 2025 VFR conditions are expected throughout the TAF period with increasing winds to around 10-15 kts for the afternoon with gusts as high as 20-25 kts in unsheltered areas of southeast MN and northeast IA. Sky cover will begin to increase from west to east late this afternoon as an incoming disturbance approaches from the west with rain chances increasing after 06z Tuesday. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Skow AVIATION...Naylor