Ashippun, WI Weather

This Hazardous Weather Outlook is for portions of east central Wisconsin, south central Wisconsin and southeast Wisconsin.

Day one: Tonight

No hazardous weather is expected at this time.

Days two through seven: Saturday through Friday

No hazardous weather is expected at this time.

Spotter information statement

Spotter activation will not be needed.

Key messages

- Sprinkles and light shower chances increase from southwest to northeast this afternoon.

- Light rain (40-80% chance) likely early Saturday morning through the afternoon. Very small chance for thunder Saturday afternoon.

- An unsettled weather pattern will develop early next week and bring periods of rain through the work week.

Short term

Issued 321 PM CDT Fri Oct 30 2026

Rest of Today: Issued 241 PM CDT Fri Oct 30 2026 We are seeing light showers moving into southwest and portions of south central WI this afternoon. Timing on the leading edge of these, if they hold together and can win over the low level dry air, is around 4 PM in Milwaukee. These are associated with weak 850- 700mb warm air advection and a mid level shortwave trough within the right entrance region of an upper jet. The majority of showers are tracking across northern IL with the shortwave, while the lighter showers in southwest WI are with the warm air advection. Surface high pressure and low level dry air will hold strong over the Great Lakes through tonight, so there is not a lot of confidence in seeing anything more than sprinkles or a brief shower hitting the ground, especially closer to Lake Michigan.

Tonight through Sunday:

Light showers associated with weak 850- 700mb warm air advection will continue to increase in coverage tonight. Surface high pressure and low level dry air will hold strong over the Great Lakes through tonight, so there is not a lot of confidence in seeing anything more than sprinkles or a brief shower hitting the ground, especially closer to Lake Michigan.

By early Saturday morning, between 3 and 6 AM, steadier showers will start to spread northeastward into southern WI as the next mid level shortwave works its way into the area from the central Plains. This will be accompanied by weak 850-700mb warm air advection and the right entrance region of an upper jet as well. Models are showing moist adiabatic profiles so not expecting thunder with this round. By the afternoon, the steadier rain should become less widespread and more showery, but a little better vorticity advection could introduce some weak instability and therefore I added a very small chance for thunder toward the IL border. Confidence in seeing any lightning is low.

The shower activity will taper off Saturday evening and allow for outdoor festivities to not be completely interrupted. Some weak vorticity advection near the IL border could allow for light showers or sprinkles though, so kept the small chance in the forecast.

Sunday, we will have weak another shortwave tracking across IL that could clip southern WI during the day. We are carrying a slight chance of showers for this feature, but the better forcing will remain well to the south. Temperatures will spike up into the mid 60s, well above normal, once again.

Cronce

Long term

Issued 321 PM CDT Fri Oct 30 2026

Monday through Friday:

An amplified trough will develop over the western half of the country early next week. This will bring showers to southern WI at times through the work week. Our first likely chance for showers will arrive on Monday afternoon along a warm front as low pressure approaches from Nebraska. With the warm air advection, vorticity advection, and weak low level jet, we cannot rule out some elevated thunderstorms.

The thing to watch as this forecast comes closer in time is the mid level vorticity pattern. We have a series of upper lows that will be swinging through the general upper trough. The upper lows/shortwaves are going to drive the strength and location of thunderstorms on Tuesday. With fairly significant differences between the models at this time, there is a great deal of uncertainty on our thunderstorm chances for the Tue-Wed timeframe.

Depending on how quickly that upper low moves out, we may have chances for showers lingering later in the work week.

Cronce

Aviation

Issued 241 PM CDT Fri Oct 30 2026

Mid clouds are spreading into southern WI this afternoon. Sprinkles and light showers are working into southern WI this afternoon. Then more widespread and persistent light showers are expected early Saturday morning through Saturday afternoon on increasing south- southeast winds. There could be pockets of MVFR ceilings and visibility Saturday morning. There is a very small chance for thunder Saturday afternoon.

Cronce

Marine

Issued 241 PM CDT Fri Oct 30 2026

High pressure around 30.4 inches crossing the Upper Great Lakes Region will slowly exit overnight. Moderate southeasterly winds return for Saturday as low pressure around 29.8 inches moves into the central Plains. Light to moderate southeasterly to southerly winds then persist into Monday, increasing for Tuesday as low pressure approaches. Southerly gales are possible on Tuesday.

Steady southeast winds will build high waves in the nearshore areas north of the North Point Light Saturday afternoon. A Small Craft Advisory is in effect.

Watches, warnings and advisories

WI: None. LM: Small Craft Advisory: LMZ643-LMZ644: 1 PM Saturday to 10 PM Saturday.