textproduct: Northern Indiana

KEY MESSAGES

- Severe thunderstorms are expected to develop over the next few hours and race east-northeast.

- All severe hazards are expected, including damaging winds, large hail, tornadoes, and heavy rain. The risk is greatest along and south of the US 24 corridor.

- Additional rain this weekend warrants a flood watch for a portion of the area.

DISCUSSION

Issued at 317 PM EDT Wed Apr 2 2025

The table is set for severe thunderstorms to develop over the next several hours. The warm front is now surging toward the US 24 corridor. The low-level surface flow is veering in response and instability is ballooning toward 1000 j/kg MUCAPE south of the front. This warm sector will be the primary area of interest for storm initiation over the next few of hours (this warm sector extends west into Illinois). Storms along or very near the warm front will be most at risk for producing tornadoes, along with any discrete storms in the warm sector. These discrete storms can also produce large hail (1.5" hail was observed this morning). Low-level helicity values of 500 m2/s2 are very accommodating to tornadoes while LCLs near 1000m are a little high, but sufficient. Forecast soundings ahead of any suspected storms exhibits a subtle cap, but one that will be quickly overcome in this robust environment. Storms are anticipated to congeal into a line as the evening wears on, posing a significant risk of damaging wind gusts along with embedded, short-track tornadoes.

The heavy rain risk continues amid our anomalously moist air mass. Thunderstorms this morning were efficient rain producers with a large portion of the forecast area picking up a radar-estimated 1 to 1.5 inches in a short amount of time. Rivers have responded accordingly and several river flood warnings are in effect. Additional rain is expected Friday through the weekend, warranting a flood watch for a portion of the forecast area where 3 to 4 inches of additional rain is anticipated tonight through Sunday morning.

Drying out overnight as the low wraps up over the upper Great Lakes and the dry slot moves overhead. Remaining breezy, however, especially in the vicinity of a secondary cold front that approaches Thursday afternoon. Can't rule out some lake effect showers, but westerly flow may be too strong and the fetch to narrow to be effective. This cold front gets shunted north as an influx of Gulf moisture and WAA races in. A thermal gradient sets up over the Ohio River Valley through the weekend (remarkable flooding anticipated in some areas) and is the focus for numerous rounds of showers and thunderstorms. Our far southern Counties (Jay IN to Allen OH) faces a glancing blow of showers and storms Thursday night. Probabilities are higher through Friday, especially south of US 30, as this frontal boundary lifts north. Rain on Friday through the weekend will worsen any ongoing river or areal flooding.

A sharp low pressure centered races in Monday bringing notably colder air overhead and the chance for rain and snow showers. Mercifully, drying out in the days thereafter with cold conditions easing by midweek.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 150 AM EDT Thu Apr 3 2025

VFR conditions should settle in for both sites through the period as drier air works in. Small T/Td spreads would have resulted in some fog issues with the clearing, but given the strong winds still in place suspect we will be fine (may have to watch for stratus development). Winds will diminish after 00Z with fog maybe becoming more of an issue outside this period.

IWX WATCHES/WARNINGS/ADVISORIES

IN...Flood Watch through Sunday morning for INZ009-017-018-020- 022>027-032>034. OH...Flood Watch through Sunday morning for OHZ001-002-004-005-015- 016-024-025. MI...None. MARINE...Small Craft Advisory until 8 AM EDT this morning for LMZ043- 046.