textproduct: Green Bay

KEY MESSAGES

- There is a chance of thunderstorms through early this evening. A few strong storms capable of producing small hail and gusty winds are possible, mainly in parts of central and east-central Wisconsin.

- Rainfall and runoff will likely lead to rises on area rivers, which may lead to minor flooding at a few locations late this week.

- The active weather pattern will abate once this system departs by Thursday morning across northeast Wisconsin.

DISCUSSION

Issued at 201 PM CDT Wed Apr 2 2025

Short Term...Tonight...Thursday...and Thursday Night

The latest RAP analysis and satellite/radar imagery show low pressure lifting northeast over northern Iowa early this afternoon. A warm front extends southeast from the low across central Illinois and Indiana. As the dry slot advances into southwest Wisconsin, widespread precipitation has exited across the northeast part of the state. Additional shower activity over western Wisconsin will likely move into north-central WI where temperatures in the low to middle 30s. This precip will likely bring a rain snow mix for the rest of the day. Other widely scattered showers could pop up at any time as well.

Further south, concern shifts to thunderstorm potential as elevated instability lifts north into Wisconsin. Thunderstorm activity has been confined to south of areas from Madison and Milwaukee so far today. Short range models have backed off on lifting most unstable capes upwards of 800 j/kg like they were showing yesterday. Instead, convective allowing models support most unstable capes around 200-300 j/kg which may be good for isolated storms late this afternoon into early this evening (from about 3-8 pm). While storms could produce small hail, the threat of severe storms is very low.

As low pressure traverses the region, focus of this forecast then turns to small precip chances along with gusty winds for the rest of tonight into Thursday.

Precipitation trends tonight: Low pressure will travel from west- central Wisconsin at 7 pm to western Lake Superior shortly after midnight. Scattered showers and perhaps a few thunderstorms will rapidly lift to the northeast across north-central and northeast Wisconsin this evening. Then light snow will wrap around the cyclone and return to north-central WI after midnight into Thursday morning. A dusting of snow will be possible before the snow showers come to an end by midday Thursday.

Gusty winds: Cold advection moves into the region after midnight via west winds. Low level lapse rates will take some time to steepen, so think gusts from 20-30 mph will be possible late tonight. But both the RAP and the HRRR indicate that there will be a period of gusty winds 30-40 mph on Thursday morning with help from surface heating. This gustiness should diminish on Thursday afternoon, leading up to winds becoming calm on Thursday night.

Temperatures: Near normal on Thursday with highs ranging from the lower to middle 40s at most locations. With better radiational cooling conditions, temps to fall into the lower 20s to lower 30s on Thursday night.

Long Term...Friday Through Wednesday

A quieter pattern is in store for northern Wisconsin over the next week. A northern stream trough will amplify and dig across the western Great Lakes this weekend. While this trough will focus the storm track over the Ohio Valley, light rain and and snow will be possible at times from Saturday through Monday. Minor accumulations will be possible, particularly at night. The highest chances for minor accumulations will be on Friday night and also Sunday night into Monday.

Thereafter, polar high pressure will build into the region on Monday and Tuesday before departing on Wednesday. As the high departs, warmer air will gradually push back into the region. Monday and Tuesday look to be the coolest days over the next week (besides today) with highs ranging from the lower 30s to middle 40s.

AVIATION

for 06Z TAF Issuance Issued at 1034 PM CDT Wed Apr 2 2025

Poor flying conditions will continue late this evening and into early Thursday (mainly LIFR/IFR/MVFR) as low pressure lifts northeast across the region. Some drizzle and fog (locally dense) will end late this evening a cold front moves through, with some lighter snow showers possible over north central WI overnight into Thursday morning. A few spots over the far south could remain VFR for a time late this evening, but this looks to be short-lived as clouds will spread back into or redevelop in any areas of clearing. Some improvement to ceilings are expected on Thursday, especially in the later morning and afternoon. East to southeast winds will continue to shift to the west overnight and become gusty, with gusts to 30-35 kts into Thursday morning. Winds will decrease Thursday afternoon.

Strong winds aloft will continue to produce LLWS into tonight, especially when winds at the surface die off a little. The LLWS threat will end Thursday morning.

GRB WATCHES/WARNINGS/ADVISORIES

None.