textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Significant severe storms are possible this afternoon and evening. Tornadoes, damaging winds, and large hail are all possible. There is a small potential for flash flooding especially in urban areas.

UPDATE

Issued 727 AM CDT Thu Jun 11 2026

The thunderstorms that fired along the nose of the low level jet in southern NE overnight have evolved into an eastward moving complex across Iowa this morning. The northern portion of this complex is expected to clip southern WI. Storms in this area will likely be elevated and post a threat for small hail. Can't rule out a since strong storm or two, but no widespread severe with this round.

Early this afternoon, we can expect numerous storms to develop in eastern IA and southwest WI as the nose of the low level jet pushes in and surface low pressure strengthens in central IA and tracks through central WI. The increasing southerly winds and low level jet will usher higher instability, very strong shear (low level and bulk), and high helicity into southern WI. This very unstable layer should zipper up toward Madison and expand eastward along I-94. However, there is some uncertainty and it could remain closer to the IL border (or zip farther north). Regardless, we have a very good setup for high-end severe storms with tornadoes, damaging winds and large hail, especially toward the WI/IL border in south central WI. As the storms track eastward, they will evolve into a line for a more widespread damaging wind threat but also tornadoes (due to high 0-3km shear).

The main message we want to share is that today has a higher tornado risk than yesterday. Be weather aware, have multiple ways to receive warnings, and have a plan to take immediate action if a tornado warning is issued for your location.

Increasing south-southeast winds along the lakeshore and over southern Lake Michigan this afternoon will bring high waves to the lakeshore areas between 4 and 11 PM, especially north of Port Washington. We will briefly have a high swim risk for that area, but then winds will become offshore as storms are rolling through between 6 and 9 PM.

Cronce

SHORT TERM

Issued 1256 AM CDT Wed Jun 10 2026

Today and tonight:

The thunderstorm east of Monroe will drift into IL early this morning with only slight chances for redevelopment through 08-09Z. Although the cold front will continue to dissipate west of the MS River, drier air at 925-850 mb on wly winds will contribute to the ending of the showers and storms early this morning. Areas of light fog and low stratus may form early this morning given the moist conditions and weakening sfc winds.

The potential for significant severe thunderstorms still looks fairly probable today as low pressure and a vorticity maximum tracks newd from KS this morning reaching ne IA by 18Z then into east central WI by 00Z Fri. A strong sswly low level jet of 50 kt will quickly surge nwd ahead of the low bringing a round of low to mid level warm, moist advection and showers and storms to srn WI from late morning into the early afternoon. These storms will likely be elevated with the potential for large hail. As the sfc low tracks from ne IA to east central WI accompanied by the trailing cold front, high thetae air will surge north across srn WI with a MLCAPE gradient from 1000-1500 J/KG over central WI to 2500-3000 J/KG toward the IL border. Strong deep layer and low level shear will be in place as shown by large, curved hodographs. CAMs are not surprisingly highlighting supercells via updraft helicity, but also line segments with a QLCS as the predominant mode. Isolated tornadoes, damaging winds, and large hail are all probable including some significant occurrences of each possible.

Wly winds and cold advection will then prevail in the wake of the storms this evening. Temps are expected to drop into the 50s by sunrise Fri.

Gehring

LONG TERM

Issued 1256 AM CDT Wed Jun 10 2026

Friday through Wednesday:

Light to modest wly surface winds, dry weather, and near normal temps will return for Friday in the wake of a cold front Thu nt. Otherwise zonal flow will prevail into the weekend. A weak trough in the low to mid levels will approach from the west Sat afternoon and pass Sat nt. Weak low to mid level warm, moist advection, but slightly stronger frontogenesis in that layer will support 60-80 percent chances of showers and thunderstorms.

A larger scale upper trough will then become established over Ontario early next week including weak shortwave troughs rotating across the region. This will bring below normal temps to srn WI, and shower chances of 20-40 percent at times through Wed.

Gehring

AVIATION

Issued 727 AM CDT Thu Jun 11 2026

Stratus with ceilings between 400 and 1400 ft AGL developed in a strip across southern WI early this morning. There are clear skies in southeast WI and central WI, but the low ceilings are a little transient. Expect the MVFR/IFR clouds to diminish around mid morning, but there is uncertainty here. A complex of thunderstorms rolling across IA will track into northern IL and southern WI, with the stronger portion on the IL side. This should arrive in south central WI around 10 or 11 AM and should have a diminishing trend to the precip. Did not include it in the eastern TAF sites at this time.

Severe thunderstorms are likely across south central WI, especially toward the IL border. All hazards are possible. Tornadoes/large hail/wind in south central WI and then wind/tornadoes in southeast and east central WI.

Look for gusty south winds ahead of the storms and gusty west winds behind them. Winds will diminish overnight as skies clear out.

Cronce

MARINE

Issued 727 AM CDT Thu Jun 11 2026

Modest south to southwest winds can be expected through this morning but will become breezy south to southeasterly this afternoon. This will occur as low pressure around 29.5 inches moves from eastern Iowa to central Lake Michigan by early evening, then northeast into Ontario by early Friday morning. Winds will become westerly and breezy behind the low pressure area this evening into the overnight. Modest to breezy southwest winds will follow for Friday into Saturday. Numerous thunderstorms are expected this afternoon and evening and may become severe.

A small craft advisory is in effect from this afternoon through tonight for wind gusts and elevated waves. Highest waves toward Sheboygan.

Cronce

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Small Craft Advisory...LMZ643...4 PM Thursday to 4 AM Friday.

Small Craft Advisory...LMZ644-LMZ645-LMZ646...4 PM Thursday to 11 PM Thursday.