Area Forecast Discussion

KEY MESSAGES

- Increasingly humid with 60-80% chances for showers and storms this afternoon and evening.

- There is a Slight Risk for severe weather (level 2 of 5) along and south of US 30 today. Best chances for severe weather will be between 3-9 PM EDT with damaging winds and large hail as the main threats.

- Daily periodic chances for showers and storms possible through next weekend, especially Monday into Tuesday night with 60-80% chances.

- Hot and humid, especially from Wednesday into next weekend. First 90+ degree day of the year likely by late next week.

DISCUSSION

Issued at 1226 PM EDT Sat Jun 6 2026

Visible satellite imagery illustrates that clearing is ongoing for our forecast area as of midday. A cold front currently extends from Rockford, IL over Lake Michigan to Grand Haven, MI. Out ahead of it, an outflow boundary is noted in the WPC surface analysis over La Porte and Berrien counties. Large scale ascent amidst an unstable environment will allow for scattered discrete storms to develop along that remnant outflow boundary as the cold front pushes southward. Severe weather is most likely today during peak heating hours (3 PM EDT and onwards). Concerns yesterday and overnight were that coverage and intensity of storms would depend on how the morning evolved. The environment has recovered favorably behind morning convection with 2500 J/kg of SBCAPE noted in northwest Indiana with an uncapped environment. 0- 6km shear has increased as well to around 35-40 kts. However, it is important to note that lapse rates are meager in both the low and mid levels at only around 6-6.5 C/km. Recent surface observations show that increased moisture has worked into the area with dewpoints around 70 and increased WAA due to southwesterly winds. Increased moisture combines with daytime heating (highs in the low to mid 80s today) to support explosive SBCAPE of up to 3000 J/kg. No towering cumulus can be seen on satellite yet, but convective initiation should occur in the next few hours mainly along and south of I-80/I-90. A Slight Risk (level 2 of 5) for severe weather is in place across northwest Ohio and northern Indiana, mainly along and south of US 30 where the greatest coverage of storms is expected. Despite lapse rates not being as steep as previously forecast, scattered instances of damaging wind and hail are still expected today along and south of US 30 given aforementioned favorable shear and instability. With PWATs around 1.5", even sub-severe storms will likely be efficient rainfall producers today with rainfall rates in excess of 1"/hr.

The aforementioned cold front will stall over our forecast area (most likely the US 24 corridor) overnight into Sunday morning, resulting in lingering showers and storms. As instability builds during the daytime, chances for precipitation creep back up in the vicinity of the stalled front, mainly along and south of US 30. High pressure centered over Ontario will keep Lower Michigan mainly dry tomorrow. Highs will be in the low to mid 80s.

The stationary front then is pulled northward as a developing low pressure system lifts into the Upper Midwest into Wisconsin on Monday. This frontal system will bring renewed chances for rain and storms as high as 60-80% area-wide, mainly Monday afternoon through Tuesday.

It will then become hot and humid, especially from Wednesday onwards into next weekend. As an upper level ridge builds across the central CONUS, summer-like temperatures in the upper 80s to low 90s are anticipated. The first 90+ degree day is likely for many locations by the end of the week. Heat indices may approach 100 degrees during peak heating hours. Depending on the amplitude and center of the upper level ridge, there could be daily periodic chances for rain/storms by mid to late in the week. For now, have kept NBM low chances (20-40% each day) for Wednesday and beyond in the forecast due to low confidence.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1213 PM EDT Sat Jun 6 2026

Inherited TAFs are overall in good shape for the 18z cycle. KSBN continues to look dry for the remainder of day; Cannot completely rule out an isolated -TSRA prior to 23z, yet most guidance suggests storms develop south of KSBN. The PROB30 group continues at KFWA as there remains uncertainty with the coverage of storms this afternoon. Satellite will be monitored closely these next few hours. Otherwise, at both sites, wind is light and variable for a time overnight before becoming easterly with high pressure setting to our north.

IWX WATCHES / WARNINGS / ADVISORIES

IN...None. OH...None. MI...None. MARINE...None.