textproduct: Indianapolis

KEY MESSAGES

- Flood Watch from late this afternoon through Saturday morning for southwest portions of central Indiana with 1 to 3 inches of rain possible

- Multiple rounds of showers and storms producing torrential rainfall and localized flooding later today into the weekend

- Isolated severe storms possible this afternoon and evening and again on Friday

- Hot and humid conditions expected for much of next week with multiple days in the 90s

DISCUSSION (This evening through Thursday)

Issued at 134 PM EDT Thu Jun 25 2026

A ridge over the Intermountain-West along with weak troughing over Eastern Canada is creating a strong jet streak over the Upper Midwest today leading to a corridor of broad synoptic lift. This in combination with a mostly saturated 925-700mb layer and weak mid- level instability will likely lead to pockets of showers and thunderstorms throughout the afternoon and into the evening. These showers should mainly be diurnal, as cooling post dusk should cap the environment and prevent initiation with forcing primarily attached to synoptic scale jet dynamics.

Most of these showers and storms should remain mundane, but there is enough upper to mid level shear for a few pockets of organized clusters to form this afternoon once updrafts are able to reach 18- 20kft. For this reason a few isolated damaging wind gusts cannot be ruled out, primarily south of the I-70 corridor. The other potential concern this afternoon and evening will be localized flooding. The primary area to watch will be along and south of a line from Sullivan to Bedford, as over this area are a few lingering, old outflow boundaries and slightly lower flash flood thresholds due to prior rainfall. Rain rates will be fairly efficient with this storm clusters and anywhere in this area that receives 2-3" in a 3 hour period will be susceptible to flooding.

For tomorrow, the primary forcing will switch to a more organized mid-level shortwave of which will likely produce numerous to widespread showers and thunderstorms throughout the day. Initially, modest isentropic lift ahead of the wave will likely push thunderstorms into Indiana between 6-9AM. Although severe weather is unlikely with this first round, a narrow corridor of 750-1500 MUCAPE south of I-70 could lead to a few strong updrafts with small hail and gusty winds.

The primary severe threat will be later in the day as destabilization occurs in a quasi-warm sector. Low level cyclogenesis is expected across IL throughout Friday, but the magnitude of pressure depletion is still widely varied amongst ensemble members. The current most likely scenario is for weak pressure depletion and the greatest zone of 30kt+ shear and 1500m2/s2 of instability to remain over far SW and S central Indiana. However, there are a few members hinting at deeper cyclogenesis and therefor a greater push northward in favorable parameter spacing. Within this zone, all severe hazards will be possible, but the primary threat will be isolated tornadoes and damaging wind gusts.

Flooding will also be a potential hazard tomorrow as generally these showers and storms will remain over the same areas throughout the day. Each individual storm will likely progress quick enough to avoid issues, but the consistency of initiation could lead to narrow swaths of training storms and 2-4 inches of rainfall.

After the passage of the wave, weak CAA will attempt to push a boundary through central Indiana Friday night, but the forcing will quickly push eastward, likely stalling the boundary over the Ohio Valley on Saturday. This will likely lead to additional showers and storms, with a low threat for isolated damaging wind gusts within microbursts. These storms are likely to move slower due to lack of steering flow, creating an additional flood threat Saturday afternoon and evening.

In the wake of convection late on Saturday, the upper ridge will expand into the area with the front lifting away to our north. This will serve as the transition point towards progressively hotter and more humid conditions that are likely to last well into next week. Multiple days with highs in the 90s are anticipated through much of next week with the highest heat indices of the summer so far rising into the low 100s during the afternoons. Isolated late afternoon and evening convection may develop by the second half of next week as the mid level heights begin to fall back. As the upper ridge will retrograde back to the southwest by next weekend, will need to monitor for an increased risk for convective clusters riding along the periphery of the ridge impacting parts of the region.

AVIATION (18Z TAF Issuance)

Issued at 134 PM EDT Thu Jun 25 2026

Impacts:

- Scattered storms this afternoon and evening

- MVFR ceilings and more widespread showers arrive near daybreak Friday

Discussion:

Instability will slowly increase throughout the afternoon, leading to the inclusion of scattered thunder and will carry a 4 to 6 hour period of PROB30s at all terminals except for KLAF.

Showers will linger in the vicinity of the boundary across southern portions of central Indiana tonight in advance of an area of more widespread rainfall that will expand into the region just before daybreak Friday. MVFR ceilings are likely to accompany the broader area of rainfall early Friday.

W/SW up to 10kts this afternoon will becoming light and variable this evening.

IND WATCHES/WARNINGS/ADVISORIES

Flood Watch from 5 PM EDT this afternoon through Saturday morning for INZ051>053-060>062-067>070.