textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Dry, but cooler today (Wednesday) through Thursday with highs in the 50s to lower 60s due to onshore flow off of Lake Michigan.

- Expect a gradual warming trend through the Memorial Day weekend.

- Rain chances return Friday afternoon and night (40-70%), with lower chances through the holiday weekend.

SHORT TERM

Issued 1120 PM CDT Tue May 19 2026

Today through Thursday:

Clouds linger overnight into early Wednesday morning as the backside of the upper-level shortwave trough swings across the the Upper Midwest. This cloud cover will help insulate temps from falling as low as they could, but still expecting lows in the 40s overnight. If there is any breaks in the clouds before sunrise, could not rule out a few inland location dipping into the upper 30s.

Otherwise the midweek pattern will be dominated by high pressure building into the Upper Great Lakes region through the day Wednesday. While expecting dry weather to prevail, expecting northeast to easterly flow off of Lake Michigan through Thursday. Thus, temps will remain much cooler along the lake and inland to along the Kettle Moraine. Mainly looking at highs in the 50s to around 60F, with coolest temps closer to the lake. Meanwhile west of the Kettle Moraine will be less influenced from the onshore flow, but still looking at daytime temps in the lower 60s. Thursday is actually looking slightly cooler further inland giving the easterly as compared to the northeasterly winds today (Wednesday). However models continue to pick up on a lake breeze developing later in the day due to the stronger temp gradient paired with enhancement of the building high pressure to the north. Thus this could push the cooler temps inland faster in the afternoon than the current forecast, but expect temps to fall pretty quick behind this lake breeze/front later in the afternoon/evening dipping into the lower 50s and upper 40s with overnight lows for Wednesday night in the lower 40s. Thursday night lows will be fairly similar in the 40s with prevailing east winds as well.

Wagner

LONG TERM

Issued 1120 PM CDT Tue May 19 2026

Friday through Tuesday:

An upper level trough will descend down from western Canada into the northern plain then pivot northeast toward James Bay for the weekend. As this upper level low pivots through Minnesota Friday, a short wave will begin to pull up from the desert southwest late Saturday into Sunday. Weak WAA will be in place through the weekend so combined with the lift there will be chances for rain Friday through Sunday. Friday by far looks like the best time for rain with POPs around 60-80% Friday night. POPs are trending later in the day which seems to be a combination of dry air in the low level that will delay onset and guidance overall trending a bit later in the day. If this trend continues I could see the onset of rain and maybe a few storms trending a bit later yet.

For Saturday and Sunday the lift from the shortwave will be a bit weaker. Given this and the differences in timing and location across models, POPs are hovering around 15-25%. WAA will cause temperatures to climb both days with highs in the 60s Saturday and mid 60s to upper 70s Sunday. So the instability should be there and moisture, it will just depend on where and when this larger scale lift moves through. Regardless this should be less organized and more scattered than Friday. Definitely NOT a wash out.

A quick area of weak high pressure looks to try to traverse the Great Lakes Region for early next week. Guidance currently has some low chance POPs for Monday and Tuesday, but unsure if this will actually materialize. While the high pressure system is on the weaker side the stationary front across the Ohio River Valley should be far enough away to prevent any showers and 500mb clusters look to keep the ridging in place aloft. I'm sure there are a few ensemble members trying to bring more moisture and mid level support further north to justify the low POP (10-20%). Either way, the better organization is to the south, which means at worst it would be isolated to scattered showers even if those few ensemble members hold out. Temperatures look to continue to warm into mid week with a return to the 80s.

Patterson

AVIATION

Issued 1120 PM CDT Tue May 19 2026

Still some pockets of lingering MVFR ceilings around 3kft, but otherwise seeing with VFR ceilings between 3.2-4kft or swaths of clearing continue tonight. Expect the VFR ceilings to prevail into Wednesday morning as high pressure begins to build into the area. despite the high pressure, still expecting to see some mid-level diurnal driven cumulus develop through the afternoon, but with more onshore flow off of Lake Michigan could even see some lower MVFR sneak in for some of the eastern lakeshore terminals through the day. As for winds, west-northwest winds overnight will turn more northeasterly through the morning and gradually pick up through the afternoon. Then as the high settles over the Great Lakes, expect a lake breeze to develop and surge inland bringing breezy easterly winds behind it through the later afternoon and evening.

Wagner

MARINE

Issued 1120 PM CDT Tue May 19 2026

Lingering gusty winds this evening, but will gradually diminish overnight as high pressure builds into the Upper Great Lakes region Wednesday and Thursday. Still looking at gusty northeast winds through midweek, especially over the southern half of the lake and building waves along the western lakeshore. High pressure continues to build to as it lifts northeastward across Ontario and Quebec Friday through the weekend with easterly winds persisting across Lake Michigan. Expecting winds to increase during this timeframe as well with a broad low pressure trough setting up over the Plains.

Wagner

MKX WATCHES/WARNINGS/ADVISORIES

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