Area Forecast Discussion

KEY MESSAGES

- High temperatures around 90 degrees coupled with humid conditions are expected again today so a heat advisory has been issued for the area. If venturing outside, be sure to take breaks and stay hydrated.

- Chances for severe weather exist again tonight. Damaging wind, hail, heavy rain, and a few tornadoes are possible with this severe weather threat. - Next chances for showers and storms return Saturday night with another cool frontal passage, bringing cooler temperatures into low/mid 70s to lower 80s along with decreased humidity across the area Sunday and Monday.

- A moderate swim risk exists along the southeast Lake Michigan shoreline today and Friday as waves reach 2 to 4 feet. Breaking waves and currents are expected. Stay away from dangerous areas like piers, breakwalls, and river outlets. Always have a flotation device with you in the water.

DISCUSSION

Issued at 349 PM EDT Thu Jun 11 2026

Severe weather is still looking likely tonight. The main line of storms will be associated with a cold front currently located over central WI/IA and northwest MO and orientated in a northeast to southwest manner. This front will push continue to push eastward this evening and the timing still is looking good for this front to approach our western edge of the CWA around 9 PM EDT. Now there is a concern that some scattered storms may pop-up ahead of this front that could impact our area earlier due to an old linear MCS associated with an old outflow boundary that has transited eastward across eastern IA/MO and through central IL earlier today. Current radar shows that some of that activity has made it to the eastern IL/western IN border. With the very unstable airmass still present it would not take much to get storms to develop from any outflows that push out from these storms.

All of the ingredients for severe weather will be present this evening with temperatures in the mid to upper 80s and dew points in the upper 60s to low 70s in place across the CWA and this will provide decent surface instability with about 2500-3500 J/kg of SB CAPE. The frontal boundary will also provide a good lifting focal point (or even a stronger outflow boundaries that may be present ahead of the front). Effective bulk shear values of 35 to 55 kts are available with the higher values located across our northwestern portions of the CWA. 300-400 m2/s2 of SR Helicity is also available ahead of the cold front which will increase the tornado threat especially earlier in the evening. SPC currently has a majority of our area under an enhanced severe storm risk this evening.

The aforementioned storms that are just to the west of our area could affect the environment and mitigate some of the potential available for when the front does arrive. So will need to see how that pans out and could be a fly in the ointment. There also is the expectation that storms will weaken the further east they move through the night so the better chances for severe storms will be further west but cannot rule out a few storms remaining strong well into the overnight period if the storms can manage to remain balanced and not be overwhelmed by a descending cold pool. The storms should be through the area by 3 to 4 AM EDT and again all threats are on the table but the most likely threat will be winds and a few tornadoes. Heavy rainfall will accompany these storms but there will be good forward movement to help keep the flooding risk at bay.

In the wake of the cold front we will have a cooler and drier airmass move into the area and should provide a very nice couple of mostly sunny spring days on Friday and Saturday with temperatures in the mid 70s to mid 80s. The important part is the humidity will be decreased with dew points dropping back into the 50s.

The next chance of showers and storms will arrive late Saturday and into Sunday morning with another cool frontal boundary pushing through. SPC does currently have our area under a marginal risk with that but the diurnal timing looks to perhaps limit the potential of the storms and will need to monitor that once we get through tonights event.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 111 PM EDT Thu Jun 11 2026

VFR conditions for a good majority of this TAF period. However, a northerly to southerly orientated cold front pushing out from IL/WI will push eastward through the area and we will see a mostly linear thunderstorm complex pushing eastward along the boundary bringing MVFR cigs/vsby conditions with temporary reductions in vsbys to IFR cat due to heavy rainfall. Current thinking for the timing looks to be around 03z Fri for KSBN and the feature should arrive at KFWA around 05z Fri. There is a possibility for a few scattered thunderstorms to develop out ahead of this front as early as 00z-01z Fri but confidence is not high in this outcome and would be difficult to nail down exactly where these will pop up if they do. Southwesterly winds gusting to around 30 kts will become westerly with the cold front with gusts around 20 kts post frontal.

IWX WATCHES / WARNINGS / ADVISORIES

IN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for INZ005>009-012>015-017-018-020-022>027-032>034-103-104- 116-203-204-216. OH...Heat Advisory until 8 PM EDT this evening for OHZ001-002-004- 005-015-016-024-025. MI...Heat Advisory until 8 PM EDT this evening for MIZ078>081-177- 277. MARINE...Small Craft Advisory until 5 AM EDT Friday for LMZ043-046.