textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Another round of showers and storms late tonight into Tuesday with a potential for strong to severe storms.

- Cool and drier weather then returns for midweek.

- Rain chances return Friday (45-55%), followed by a gradual warming trend Saturday into early next week.

SHORT TERM

Issued 200 PM CDT Mon May 18 2026

Late this afternoon through Tuesday night:

Quiet weather largely expected the rest of the afternoon into the evening with remnant convection moving off to the east with quite a bit of clearing ongoing right now ahead of developing storms to the southwest this afternoon and evening. This is what we will be monitoring tonight as it pushes into the CWA. Based on the development of this convection will in part determine how things play out tonight. Several models favor development and progression into a QLCS with a eastward progression. Most models have this potentially becoming elevated in addition to limited instability. As this pushes east toward southeast WI CAMs largely have this falling apart with very limited instability and very likely an elevated system at that point, which would reduce severe risk to essentially zero. However, it is worth mentioning that clearing this afternoon has definitely increased our severe risk as we will likely be able to hang on to a bit more instability and may avoid storms immediately becoming elevated as they reach the CWA. The best severe risk for tonight will be in southwest WI, likely southwest of Madison, with decreasing risk further east. We will need to monitor storms to the southwest tonight as the development and progression will play a role in determining the potential for severe storms later tonight.

The remnant storms and precip will push out by mid morning with our attention turning to the cold front that will closely following the exiting precip. There is a mild concern for developing storms along the front but with departing storms in the morning it does not appear there will any recovery time ahead of the front with models suggesting very limited instability and frankly not a great shear environment either. This suggests that event should week storms develop they would not likely be of concern. The front should push in by the late morning and push through all of southern WI by early to mid afternoon. The best chance for weak storm development with the front is likely in southeast WI where the best chance for recovery would be. Otherwise, expect quiet conditions into the late afternoon and overnight as winds turn northwest behind the front with higher pressure gradually pushing behind it.

Kuroski

LONG TERM

Issued 200 PM CDT Mon May 18 2026

Wednesday through Monday:

Cool and dry weather expected Wednesday and Thursday, with strong high pressure passing overhead and northeast to east winds off of Lake Michigan (around 10 to 15 MPH at times). Much of eastern WI should see highs in the 50s, with low to mid 60s further west. Some much needed calm and quiet weather.

Our next noteworthy chance for precipitation arrives Friday, with roughly half of the available model guidance resolving a low pressure system tracking northeastward from the Great Plains and approaching our region. The favored track of this system would stall it either to our south or our west, with the continued onshore flow from Lake Michigan helping to reduce instability and prevent substantial moisture return over southern WI. Hence, we only forecast slight chances for thunderstorms Friday, with rain chances increasing from 15-55% in a southwest to northeast manner as the day goes by. As with any low pressure system this time of year, we will have to keep an eye on it's track and evolution, but ensemble consensus strongly suggests insufficient moisture return / instability for much in the way of thunder.

Predictability drops substantially for Saturday and onwards, but the general consensus is a warming trend that continues into early next week.

Sheppard

AVIATION

Issued 200 PM CDT Mon May 18 2026

Conditions have quieted today with some clearing overhead right now that will gradually be impinged on today by clouds to the west. However, our attention is currently on developing convection to the southwest that will eventually track into southwest WI later tonight along with MVFR CIGS and maybe some temporarily lowered VSBYS with rain. At this time storms are not expected to be strong but there is a chances for stronger winds to linger into southwestern WI but likely weakening by the time it reaches southeast WI but some thunder could be expected all through southern WI overnight. Just after daybreak most of the rain and storms should have pushed out to the east with clouds remaining in place ahead of the front expected to come through from the late morning through early to mid afternoon. Some showers and perhaps a weak storms possible along the front but currently limited precip along the front is expected. As the front pushes through expect MVFR CIGS to clear out and likely only higher CIGS remaining behind the front. Clearing skies expected overnight.

Kuroski

MARINE

Issued 200 PM CDT Mon May 18 2026

Storms and showers are pushing out as winds behind this remain breezy from the south. These winds will increase slightly across the lake late tonight and remain breezy ahead of the cold frontal passage expected Tuesday afternoon as the low pressure system around 29.6 inches swings northeast of the Lake into Ontario. A few storms chances across primarily the south part of the lake late tonight into Tuesday morning ahead of the front. High pressure around 30.4 inches will push in behind the front with light and variable winds taking hold from late Wednesday into Thursday.

Currently the northern nearshore zone is in a Small Craft for primarily wave heights to 5 feet. Winds will become breezier tonight across much of the nearshore and thus we will have an expanded Small Craft through much of Tuesday before the front Tuesday turns winds northwest and calm to a degree

Kuroski

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Small Craft Advisory...LMZ643 until 7 PM Tuesday.

Small Craft Advisory...LMZ644-LMZ645-LMZ646...4 AM Tuesday to 4 PM Tuesday.