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

FORECAST UPDATE

Issued at 956 PM EDT Thu Jun 25 2026

Stubbornly persistent very isolated convective cells continue to wax and wane across portions of central Indiana this evening, despite the expected general downward diurnal trend in both coverage and intensity.

The going forecast is in very good shape, with no significant changes necessary. Expect mostly quiet weather through the remainder of the evening into the early overnight, before chances begin to ramp back up again late tonight as weak upstream convection moves into the area associated with a subtle upper level wave moving along the boundary in the region. A few rumbles of thunder will be possible with this and perhaps a brief heavy downpour or two, but the more significant convective concerns should hold off until the later daytime into evening hours tomorrow.

Some patchy fog will be possible overnight due to light winds and ample low level moisture, though cloud cover will limit radiational cooling and should equally limit fog coverage, though will have to keep an eye on it with the aforementioned boundary remaining in the area.

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 (00Z TAF Issuance)

Issued at 728 PM EDT Thu Jun 25 2026

Impacts:

- Convection rapidly waning across southern portions of the area

- Additional showers late tonight, storm threat Friday during the day

- Conditions deteriorating late tonight to MVFR then likely IFR during the daytime hours Friday

Discussion:

As we pass into the evening, lingering isolated showers/storms are rapidly waning across the southern portions of the area. Activity vicinity HUF/BMG will likely be nearly dissipated by valid time and will not be mentioned.

Additional activity late tonight will be possible along a stalled boundary to our south, and will carry either VCSH or a PROB30 shower group. Cannot rule out a rumble of thunder or two, but expect the more significant thunder threat to be a bit later into the daytime hours on Friday, where additional PROB30 thunderstorm groups will be carried at all but LAF.

Ceilings and perhaps visibilities will begin to deteriorate late tonight to MVFR and then likely IFR (at least for ceilings) during the daytime hours on Friday as precipitation moves along the nearly stationary frontal zone over the region. Fluctuations are likely, particularly in convection.

Winds will be westerly to northwesterly or light and variable overnight, becoming easterly or southeasterly during the day on Friday. Sustained winds are likely to be 10KT or less throughout the period.

IND WATCHES/WARNINGS/ADVISORIES

Flood Watch through Saturday morning for INZ051>053-060>062- 067>070.