Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
410 FXUS63 KMKX 252112 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 412 PM CDT Sat May 25 2024 .KEY MESSAGES... - Widespread showers and storms on Sunday, with at least a small potential for severe thunderstorms with hail and/or wind gusts. - Southeast winds and building waves are likely to create Moderate Swim Risk conditions on Sunday for Lake Michigan beaches. A High Swim Risk cannot be ruled out, and a Small Craft Advisory may be needed as well. - Chance for showers/storms Monday and Tuesday, particularly in the afternoon hours (roughly 40% chance), but quieter weather midweek. && .SHORT TERM... Issued 410 PM CDT Sat May 25 2024 Tonight through Sunday night: Quiet weather this evening into tonight, with high clouds gradually approaching. Showers and storms approach from the southwest Sunday morning, likely arriving at Janesville and Madison after 7 AM CDT and overtaking the entire CWA by noon or 1 PM. 700mb charts indicate this first wave of showers and weak thunderstorms will be driven by strong WAA and frontogenesis (decent coverage expected) but should be elevated convection and should not be severe. With a dry slot wrapping into the low pressure Sunday afternoon, and the surface warm front advancing deep into the CWA, a small window for a few severe storms is present, generally between 2 PM and 7 PM Sunday. Hail and wind gusts would be the primary concerns if applicable, and this threat is conditionally dependent on airmass recovery from the morning round of convection. Steady southeast winds are expected over a decent fetch of Lake Michigan on Sunday, with WAVEWATCH III producing waves up to 4 feet offshore of Lake Michigan beaches. This would meet the criterion for a Moderate Swim Risk on Sunday, specifically in the afternoon and evening hours. A High Swim Risk cannot be ruled out at this time. Sheppard && .LONG TERM... Issued 410 PM CDT Sat May 25 2024 Monday through Saturday: Monday and Tuesdays upper air pattern features a negatively tilted trough axis from Manitoba into Wisconsin, with multiple shortwave perturbations rotating through. Though it is less organized than Sunday`s thunderstorm setup, showers and thunderstorms will be possible Monday and Tuesday (roughly 40% chance each day), particularly in the afternoon hours. Daytime highs in the upper 60s to around 70 expected each day, with a synoptic northwest breeze strong enough to prevent any lake breeze from forming (hence, lakeshore and inland temps should be equal). A ridge in the jet gradually builds in Wednesday into Thursday, with quiet weather expected, daytime highs rising a few degrees, and a lake breeze possible. Next (potentially) active pattern would be Friday into the weekend, though predictability is very low. Sheppard && .AVIATION... Issued 410 PM CDT Sat May 25 2024 VFR conditions and quiet weather continue into tonight, with high clouds gradually approaching and winds turning southeasterly. Southeast winds become breezy after sunrise Sunday, with showers and thunderstorms overtaking the region from southwest to northeast. If we had any severe thunderstorms (low chance, but still possible) they would likely be in the 2 to 7 PM CDT timeframe. As periods of showers and storms continue on Sunday, expect cloud ceilings to lower to MVFR and eventually Fuel-Alt MVFR levels. IFR ceilings are possible late Sunday into Sunday night, with winds veering northwesterly behind the departing low pressure. Sheppard && .MARINE... Issued 410 PM CDT Sat May 25 2024 High pressure around 29.9 inches will remain over Lake Michigan this evening, then exit northeastward into Sunday. Light southerly winds continue this evening, then back southeasterly late tonight as low pressure around 29.4 inches approaches from the Central Plains. This low will move across either central or northern Lake Michigan Sunday night. Expect southeasterly winds to increase as this low approaches, followed by west to northwest winds on Monday as the low departs northeastward. Marine Hazards: Numerous showers and thunderstorms will move across the lake Sunday and Sunday night. Southeast winds and building waves on Sunday might reach Small Craft Advisory levels. On the back side of the departing low pressure, northwest wind gusts could reach Small Craft levels again on Monday, but waves will be small given the offshore flow. Sheppard && .MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...None. && $$ Visit us at weather.gov/milwaukee Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/NWSMilwaukee www.twitter.com/NWSMilwaukee www.youtube.com/NWSMilwaukee