FXUS63 KARX 262337 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 637 PM CDT Tue Sep 26 2023 .DISCUSSION...(This evening through Tuesday) Issued at 257 PM CDT Tue Sep 26 2023 Key Messages: - The low pressure system continues to rotate shower and thunderstorms through the area. Amounts look to begin to trend downward as we head through the overnight and into the day Wednesday. - Warmer and drier conditions move in for the end of the week and into the weekend. Off and on showers have continued to rotate through the area today, with hi-res guidance suggesting some increase in chances especially across portions of southwest WI this late afternoon into the evening. With model soundings suggesting limited instability, the lightning risk remains a bit lower. A few showers continue to rotate through the area overnight as the upper-level low makes its trek eastward into Illinois. Hi-res guidance suggests a slow decreasing trend in chances across much of the area, transitioning highest chances to the east/southeast. Overall, the 26.12Z HREF 24-hr probability-matched mean indicates areas of 0.01 to 0.25" with some pockets of 0.5 to 1" (mainly in the south/southeast), with only a few models suggesting low probabilities (around 10-20%) for localized spots of greater than 1.5 to 2" by 12Z Wednesday. Generally though, HREF shows highest amounts this evening with a decreasing trend in rainfall amounts through the overnight hours. Models hint at some potential for patchy fog development Wednesday morning, so will continue to monitor trends and observations through the night. The slow moving area of low pressure is expected to continue its shift eastward towards the Ohio Valley through the day Wednesday. Chances for scattered showers and perhaps a few thunderstorms linger through the day, with rainfall amounts continuing to lessen. The low looks to finally lose its grip on the area with ridging beginning to build eastward across the region Thursday. Overall, global models seem to be in fairly good agreement with the general upper level pattern for the end of the week and into the weekend, with upper level troughing over the west and ridging over the east- central CONUS. Will note that a boundary setting up around northern MN and waves of energy moving through the ridge may become the focus for some showers and thunderstorms into the weekend. However, guidance tends to lean towards keeping chances northwest of the local forecast area. There is not a strong signal in the ECMWF ensemble solutions right now, though an increase in GEFS solutions showing more members in favor of any sort of rainfall potential has been noted. For now, will stick with the current trends and maintain the drier forecast through the weekend until details are more clear. Small spread in guidance supports temperatures reaching into the upper 70s to low 80s, which is about 10-15 degrees above normal. Overall, this pattern looks to possibly bring much drier conditions to the area along with an increasing trend in temperatures as we say goodbye to September and head into the spooky season (October). && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 637 PM CDT Tue Sep 26 2023 Pockets of MVFR ceilings and visibility reductions (2-5 miles) continue this evening with scattered showers moving from east to west across southeast Minnesota. Lower MVFR/IFR ceilings take hold as we move into the overnight hours with an isolated shower possible at the TAF sites overnight. Ceilings remain MVFR/IFR Wednesday morning with scattered showers returning to the forecast by mid to late morning. Low confidence in the timing and location of showers tomorrow so only a VCSH mention at this time. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ DISCUSSION...EMS AVIATION...KAA