textproduct: Milwaukee/Sullivan

KEY MESSAGES

- A very humid airmass will return Monday and Monday night ahead of approaching low pressure with widespread showers and scattered thunderstorms forecast.

- Hot and humid conditions expected mid to end of next week with some potential for Heat Advisory conditions late next week and additional chances for storms.

SHORT TERM

Issued 145 PM CDT Sat Jun 6 2026

Tonight through Monday night:

Upper level ridging settling into the region tonight with strengthening high pressure developing over the Great Lakes region. This will keep the region dry tonight and into Sunday morning. However, models appear to indicating that storms that will have developed south and west of the CWA Sunday, primarily off of a trailing front that had become stationary, will lift north into the CWA due to an embedded shortwave lifting through the ridge. This likely to be limited spatially in terms of impact due to significant dry air further north and east as the high continues to strengthen as it pivots southeast. A few CAMs show some of this activity entering southwest portions of the CWA before rapidly dying out. The high pressure and drier air will likely hold most of the precip and storms to the west of the CWA through Sunday night but as the upper shortwave continues shifting northeast and high slides further east this will allow for the rain/storms to push in.

Looks likely that Monday could be on the wet side with strong PVA, plenty of moisture with access to the Gulf, and PWATs rising to around 2 inches. Any rain/storms would likely be quite efficient. How much rain we get from this will generally come down to whether we get more or less storm activity. There will definitely be some storm activity but the question really becomes how convoluted are storms and do we end up with more stratiform type rainfall. Either case is good because the rain is needed, however the storm potential will help determine whether there may be a risk for flash flooding rains. In addition, corfidi vectors suggest precip would likely be fairly slow moving and if we can manage some backbuilding or training there will be some flash flooding concerns. It should also be mentioned that storms are not expected to be severe given fairly limited deep layer shear around 20-30kts and frankly not overwhelming instability either (up to ~1000J/kg or so). However, that could change if we see a situation where a lingering MCV pushes overhead. In any case expect the shortwave to push out by late Monday night allowing for at least a brief period of drier air behind it by Tuesday morning.

Kuroski

LONG TERM

Issued 145 PM CDT Sat Jun 6 2026

Tuesday through Saturday:

Latest model guidance is still showing that southern Wisconsin will remain on the northwest side of upper ridging Tuesday through at least Thursday. This is expected to result in a persistent stretch of warm and humid conditions through this period. Precipitable water values are forecast to be 1.5" to 2.0", with dewpoints anywhere from 65 to 75. Above normal high temps in the mid to upper 80s may crack the low 90s at times (mainly Wed and Thu), with 925 mb temps upwards of 25C expected. By Friday morning, a cold front is expected to move through, bringing in a drier and more stable airmass along with somewhat cooler conditions. The GFS keeps the high and quiet weather in place through Saturday, while the latest ECMWF has the moisture returning Saturday along with more shower/storm chances.

Given the warm and humid conditions through at least mid-week next week, plenty of instability is expected each day. Since southern Wisconsin will be on the northwest side of the upper ridge, the door will be open for a couple shortwaves to move through during this period, bringing a chance for showers and storms at times. The best chance for storms currently looks like Wednesday and Thursday, as precipitable water values are trending a bit lower for Tuesday behind the Monday shortwave, and the cold front may be through by daybreak Friday. May see a the potential for some strong to severe storms Wed/Thu as well, given somewhat stronger shear and decent lapse rates.

It still looks like there will be the potential to approach or reach Heat Advisory levels Wednesday and/or Thursday. This will largely depend on the timing of clouds and showers/storms. Given enough sunshine during the day, heat index values will likely approach the 100 degree mark due to the warm temps and humid conditions.

DDV

AVIATION

Issued 145 PM CDT Sat Jun 6 2026

The lake breeze has pushed across the nearshore areas and continues inland this afternoon with mostly east winds behind it. Otherwise brief periods of VFR diurnal cu today with quiet and calm conditions tonight. Into Sunday there will be a chance for showers and even storms across parts of southwest WI but will likely stay south and west of the TAF sites. Better chances for MVFR CIGS and more widespread storm activity possibly impacting VSBYs will move in Sunday night but more specifically on Monday which is the next period to focus on for impacts to aviation.

Kuroski

MARINE

Issued 145 PM CDT Sat Jun 6 2026

High pressure of 29.9 inches builds into the Upper Great Lakes and strengthening to 30.1 inches overnight. Warm and humid air will linger over the relatively cool waters of Lake Michigan with a light wind regime and cause areas of fog into Sunday morning. Marine Dense Fog Advisory remains in effect until 18z Sunday for the northern 2/3 of Lake Michigan. Low pressure develops in the Great Plains Monday, bringing south- southeasterly winds through at least midweek. Additional chances for thunderstorms develop Monday with more chances throughout the week.

Kuroski

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Dense Fog Advisory...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ868-LMZ870-LMZ872 until 1 PM Sunday.