Area Forecast Discussion

KEY MESSAGES

- Several rounds of heavy rain and embedded thunderstorms this weekend. A Flash Flood Watch remains in effect for portions of the forecast area.

- Low chances for scattered rain showers linger into the first half of next week.

- Cooler next week with highs only in the 60s Monday through Wednesday.

DISCUSSION

Issued at 144 PM EDT Sat Sep 19 2026

Active weather will continue through the weekend and periods of rain will remain possible through at least midweek. A quasi- stationary frontal boundary that is currently located just south of the forecast area will be the focus for moderate to heavy rain over the next 24 hours as a series of shortwaves move over the region in near zonal flow. We are currently experiencing a general lull in precip coverage/chances which will last through mid evening before the next upper level impulse arrives. Another shortwave and theta-e surge is expected tonight, focusing locally heavy rain and embedded thunder mainly along and north of the US 30 corridor. Another round then Sunday afternoon/evening is possible, especially if/where any boundary layer heating can occur, resulting in heavier convective elements. Localized lowland and river/stream flooding, along with flash flooding, remains a concern given the saturated ground and opportunties for training elevated convection in this very moist 1.8-2.2 inch PWAT air mass. No changes were made to the Flood Watch for now (in effect through Sunday morning). Latest guidance does favor areas north of the US 30 corridor for higher probs for 1-3" plus. Luckily there are lower probabilities to the south, though any additional rain in areas just south of Fort Wayne will further exacerbate ongoing high water issues.

Drier conditions are forecast for Monday, although a weak shortwave will move through Monday afternoon bringing some light rain showers, mainly south of US 30. Then, a slow moving through that is currently situated over the northern Rockies will make its way eastward over the next several days and finally move into the Great Lakes on Tuesday. As the low crosses the area going into Wednesday, periodic showers will continue, and possibly persist into Thursday and Friday. High pressure ridging will move in behind this system for mild and dry weather next weekend.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 709 PM EDT Sat Sep 19 2026

An area of rain is approaching KSBN from the west with lightning confined to far western IL. This activity will gradually track east through the critical TAF period. With a narrow corridor of elevated instability at KSBN during the late night hours, have maintained TS there. This instability axis struggles to progress into KFWA, so, remain TS free there; confidence is low. Heading toward daybreak Sunday, showers are likely most widespread toward KSBN before becoming more focused toward KFWA. A period of dry weather is anticipated just beyond this TAF period as the low pressure system responsible drops south.

IWX WATCHES / WARNINGS / ADVISORIES

IN...Flood Watch through Sunday morning for INZ005>009-012-014-015- 017-018-023>027-032>034-103-104-116-203-204-216. OH...Flood Watch through Sunday morning for OHZ015-024. MI...Flood Watch through Sunday morning for MIZ078>080-177-277. MARINE...None.