Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
896 FXUS63 KMKX 262034 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 334 PM CDT Sat Apr 26 2025 .KEY MESSAGES... - Potential for severe thunderstorms Monday night (risk level 4 out of 5 in the west, risk level 3 in the east, except 2 along the lakeshore). Initial indications are that this activity will peak late Monday evening into the overnight with all hazard types possible. - High temperatures near 80 degrees Fahrenheit are expected Monday, then cooling down toward the middle of next week. && .SHORT TERM... Issued 334 PM CDT Sat Apr 26 2025 Tonight through Monday morning: High clouds are expected to increase late tnt via warm advection aloft as an upper ridge approaches. Although there will be ample time for temps to fall into the 30s via good radiational cooling conditions. High pressure will then move ewd on Sunday with lgt sely winds developing. Broken mid to upper level clouds are expected from the morning into the early afternoon before thinning and shifting nwd. Far se WI may remain partly cloudy for the day. High temps will range from the lower 50s at the Lake MI shoreline to lower to middle 60s elsewhere. For Sun nt, cyclogenesis will move out of the central high plains to the central Dakotas by 12Z Mon. South central WI will be on the ern periphery of a strong sly low level jet over IA and MN during the early morning hours. The LLJ axis will then shift into wrn WI by 17Z with the accompanied thetae advection. The warm, moist advection and elevated CAPE will bring chances for showers and storms during this time with chances at 50-60 percent north and west of Madison. Gehring && .LONG TERM... Monday afternoon through Saturday: The models are in fairly good agreement with a 994 mb low over the ern Dakotas at 18Z Mon tracking to north central Lake Superior by 06Z Tue, with the cold frontal passage over srn WI from 09-14Z Tue. The shortwave trough associated with the low will be deamplifying over time as it tracks from the ern Dakotas to Lake Superior. The warm sector will move into srn WI during the afternoon and evening hours with capping initially expected after any morning showers and storms. The model qpf consensus produces QPF of one half inch or greater mainly over west central WI to nw WI where the upper dynamics will intersect the plume of sfc based instability. Thus there is some uncertainty on the coverage of severe storms farther to the south over srn WI for Mon nt. The timing would appear to be late evening into the overnight. Overall will still forecast 60-80 percent chances for rain as some PVA and 500 mb height falls of 60-90 meters is forecast, and with the ability of strong shear to organize a MCS. Strong deep layer shear of 50-55 kts and 0-3 km shear of 40 kts will combine with MLCAPE of 1500 J/kg to bring a meaningful severe storm threat to srn WI especially over south central WI. All severe threats will be possible including tornadoes given the strong low level wind shear forecast, whether from a QLCS or supercells. Once again, the coverage of the severe storms is the most challenging aspect to the forecast at this time. Wly winds and drying conditions will then take hold after the frontal passage on Tue. Large high pressure will then gradually shift across the region Tue nt-Wed with relatively seasonal temps expected, but cooler near the lake. More rain may then return Wed nt-Fri as a wave of low pressure tracks from MO to the lower Great Lakes for Thu-Thu nt, which may be followed by a shortwave trough out of the northwest for Fri. High pressure to then follow for Fri nt-Sat. Temps for the 2nd half of the week will be at or slightly below normal. Gehring && .AVIATION... Issued 334 PM CDT Sat Apr 26 2025 VFR conditions this afternoon through Sunday evening. Gehring && .MARINE... Issued 334 PM CDT Sat Apr 26 2025 High pressure around 30.4 inches over Lake Superior and Wisconsin will move over Lake Michigan this evening. The high will be slow to move away with light and variable winds forecast tonight and Sunday. Low pressure of 29.4 inches will then track from South Dakota to northeast Minnesota Monday, then to Quebec by mid Tuesday morning. Expect breezy southerly winds over Lake Michigan Monday through Monday night. Southerly gales are possible, although there will be a strong inversion over the cooler open waters, so there is uncertainty that the very strong winds up to 50 kt just off the surface will be able to mix down. The associated cold front will cross Lake Michigan on Tuesday. Winds will diminish quickly Tuesday night as high pressure around 30.2 inches moves into the region. A Small Craft advisory will likely be needed Monday and Monday night from Sheboygan to Winthrop Harbor due to breezy south winds and building waves. The hazardous conditions for small craft may linger into Tuesday. Gehring && .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