Area Forecast Discussion

KEY MESSAGES

- Scattered snow showers should move east southeast through the area this morning, becoming rain showers by midday into the afternoon as temperatures warm up. No accumulations are expected, but brief visibility drops may occur.

- Frost expected tonight into early Monday morning with low temperatures at or below freezing. - Gradual warm up for start of the work week with above normal temps Tuesday through the end of the week.

UPDATE

Issued 1001 AM CDT Sun Apr 19 2026

Scattered snow showers continue to move east southeast through parts of south central and southeast Wisconsin this morning. They are being driven by differential CVA from a passing 500 mb vorticity maximum, as well as fairly robust low to mid-level frontogenesis response. These should continue late this morning, before becoming rain showers as temperature profiles warm up by midday into the afternoon. No snow accumulations are expected, but a brief visibility drop to 1 to 2 miles may occur.

Otherwise, scattered to broken clouds should linger into this afternoon. There may be a few sprinkles or light showers that occur, though forecast soundings get fairly dry. There is a little instability, so think that at least the clouds should linger, with the showers a low (under 20 percent) probability.

Gusty northwest winds should develop this afternoon, after the cold front moves through. Highs may reach the middle to upper 40s, though it will feel like the 30s to around 40 degrees with the gusty winds.

Wood

SHORT TERM

Issued 1125 PM CDT Sat Apr 18 2026

Rest of Tonight through Monday:

Winds have decoupled and will remain light under clear skies overnight. Looking at temps to dip down into the lower 30s under this clear and calm conditions. Although the official green up and growing has not been declared yet for southern WI, could see patchy to areas of frost develop overnight tonight.

Will see winds pick back up for Sunday as a mid-level shortwave trough swings through the region during the morning. Given this wave and just enough moisture may be enough to squeak out a few scattered light showers through the morning. Given the cooler temps could see a few flurries/mix as well, but overall not expecting much if any in the way of accumulations/impacts. Otherwise it will become breezy through the afternoon with temps similar to today and topping off in the 40s again. Will be another chilly night Sunday night as high pressure builds into the Upper Midwest. Calm winds, subsidence, and temps at to below freezing may result in additional frost development into early Monday morning.

High pressure works its way overhead and then eastward for Monday and will begin to see temps climb back into the 50s for Monday as southerly flow returns on the backside of the departing high.

Wagner

LONG TERM

Issued 1125 PM CDT Sat Apr 18 2026

Monday night through Saturday:

Overall fairly quiet pattern through midweek with temps gradually warming up to above normal. Start to see temps in the 70s return on Tuesday during the day as the upper-level ridge axis continues to build eastward into the Upper Midwest. However, models continue to hint at a mid-level shortwave trough trough to works its way down across the Upper Great Lakes later Tuesday. With this pattern there looks to be a low traversing into the Hudson Bay region and drag a cold front across the region. Given the more north to south trajectory of the cold front, expect it to be more in line with a backdoor cold front enhanced by the colder air off of Lake Michigan. Thus could see a quick drop in temps Tuesday afternoon into the evening with temps falling from 60s/70s into the 40s pretty quickly. Additionally given the low-level WAA and southerly flow advecting in a bit more moisture into the southern WI, cannot completely rule out a few showers and storms to develop along this frontal passage. However, given the time differences and overall drier airmass aloft, will continue with the drier trend at this time.

Temps are expected to quickly recover into Wednesday as the upper- level ridge axis continues to build across the Upper Midwest through Thursday with highs exceeding 70F. Then long range models align and project an upper-level trough to dig down across the Canadian Plains and lift into the Upper Midwest later Thursday through the start of next weekend. Expect a more active pattern toward the end of the week with a return of showers and thunderstorm chances to southern WI later Thursday into Friday as the system traverses the region. Then behind this system toward the weekend looking at cooler temps behind the systems cold front.

Wagner

AVIATION

Issued 1001 AM CDT Sun Apr 19 2026

Scattered snow showers continue to move east southeast through parts of south central and southeast Wisconsin this morning. These should continue late this morning, before becoming rain showers as temperature profiles warm up by midday into the afternoon. No snow accumulations are expected, but a brief visibility drop to 1 to 2 miles may occur.

Otherwise, scattered to broken clouds around 5000 to 8000 feet AGL should linger into this afternoon. There may be a few sprinkles or light showers that occur, though most of the afternoon should be dry. Gusty northwest winds should develop by this afternoon, after the cold front moves through.

Winds will weaken this evening and remain light into Monday morning, as high pressure moves southeast across the region. Clouds should move out of the area as well this evening, with clear skies into Monday morning. South southwest winds should develop by Monday afternoon, with a southeast lake breeze expected for terminals near Lake Michigan. There may be some lake effect clouds that move onshore in the afternoon, which may have some ceilings below 3500 feet AGL.

MARINE

Issued 1125 PM CDT Sat Apr 18 2026

Breezy northerly winds will continue across Lake Michigan for Sunday, especially across the northern third of the lake. However, light winds are expected for the start of the week as high pressure works its way across the region through the day Monday. Then winds pick up for Tuesday. May see a conditions approach small craft level in southern WI nearshores as Tuesday, breezy southerly winds should develop over the region a cold front extending from a low pressure trekking across the Hudson Bay region Tuesday works its way down the lake turning winds more northerly behind it. However will be short-lived as high pressure builds in right behind it for midweek. Small craft conditions return for the end of the week as the pattern becomes a bit more active with a develop system trekking across the Upper Midwest bring stronger southerly winds along with showers and thunderstorms chances.

Wagner

MKX WATCHES / WARNINGS / ADVISORIES

WI...None. LM...None.