


Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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205 FXUS63 KARX 191953 AFDARX Area Forecast Discussion National Weather Service La Crosse WI Issued by National Weather Service Des Moines IA 253 PM CDT Mon May 19 2025 .KEY MESSAGES... - Wet later tonight into Wednesday. 1-3 inches of rain is expected south of Interstate 94. The highest totals (2-3 inches locally as high as 3-4 inches) will be in northeast Iowa, southeast Minnesota, and southwest Wisconsin. - Some cold record high temperatures may be tied to broken on Tuesday - It will remain cool and dry from Wednesday night into the Memorial Day weekend. && .DISCUSSION... Issued at 227 PM CDT Mon May 19 2025 Wet from Late Tonight into Wednesday A 500 mb trough and 850 mb closed low pressure area will move into the area tonight. As this occurs, 850 mb moisture transport and deep moisture convergence will increase later tonight and continue into Tuesday evening. The 19.12z HREF continues to bring 1 to 1.4 inches of precipitable water values into the region south of Interstate 94. Meanwhile, a dry easterly flow will result in much lower precipitable water values (0.4 to 1 inch) for areas north of Interstate 94. Areas south of Interstate 94 will likely see rainfall amounts of 1 to 3 inches and up to 1 inch (highest near Interstate 94) for the remainder of the area. The HREF ensemble probability-match mean suggest that there may be some localized rainfall totals of 3-4 inches in northeast Iowa, southeast Minnesota, and southwest Wisconsin. With the very dry antecedent conditions over the past 3 weeks, not anticipating any issues with river flooding. Like the past couple of days, much of the instability remains south of the area. The ensemble mean for most unstable CAPEs remain below 250-500 J/kg across much of northeast Iowa and southwest Wisconsin. Several CAMs and the rapid update models /HRRR, RAP/ do depict up to 1000 J/kg of MUCAPE over the far SW section of the CWA this evening into early tonight. Effective shear values this evening do exceed 40 kts for a time, although expecting any cells to quickly congeal into a messy cluster of storms. As a result, organized severe weather in not expected. Wednesday Night into the Memorial Day Weekend In the wake of this system, northwest and north winds will bring dry and cool air into the region. High temperatures through Saturday will be primarily in the lower and mid-60s and in the mid to upper 60s for Sunday. These temperatures will be 5 to 10 F cooler than the seasonal averages for this time of year. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1220 PM CDT Mon May 19 2025 East winds will continue to advect in very dry (dew points in the lower to mid-30s) into the region this afternoon. This will result a continual dissipation of the showers west of the Mississippi River. The CAMs continue to suggest that most of these showers will not reach KLSE or much of western Wisconsin. As a result, ceilings and visibilities will be primarily VFR this afternoon. As a 500 mb shortwave approaches the area and closed 850 mb low approaches the region tonight, another round of rain will move into the area. This rain will then continue into Tuesday. Ceilings will gradually lower to IFR/MVFR overnight and early Tuesday morning. Visibilities will become MVFR around 20.08z at KRST and around 20.09z at KLSE. Finally very strong winds /at or above 50 kts/ in the 1-2k feet AGL layer will lead to period of LLWS late tonight into early Tuesday. && .HYDROLOGY... Issued at 231 PM CDT Mon May 19 2025 With it being very dry across much of the area over the past 3 weeks, still not overly concerned with river flooding at this time. While there will likely be some response in area rivers in northeast Iowa, southeast Minnesota, and southwestern Wisconsin, it would take much more QPF (3+ inches) to see rivers even approach action and/or minor flood stage. As a result, soils and rivers should be able to handle the forecasted rainfall. However, there may be some ponding of water in more urban or poor drainage areas. && .CLIMATE... Issued at 231 PM CDT Mon May 19 2025 Rain and low clouds will result in very little temperature rise on Tuesday, High temperatures will likely be in the 40s and lower 50s. These temperatures will be close to the daily record cold high temperatures for May 20. While La Crosses record of 44F in 1892 looks safe, Rochester`s cold high record of 46F in 1892 might be in jeopardy /current forecast high of 47F/. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Boyne/Fowle AVIATION...Boyne/Fowle HYDROLOGY...Boyne/Fowle CLIMATE...Boyne/Fowle