textproduct: Indianapolis

KEY MESSAGES

- Flood Watch from through Saturday afternoon for southern portions of central Indiana with 1 to 3 inches of rain possible

- Multiple rounds of showers and storms producing torrential rainfall and localized flooding expected through Saturday night

- Isolated severe storms possible across south central Indiana this afternoon and evening

- Hot and humid conditions expected for much of next week with multiple days in the 90s and heat indices over 100 degrees

FORECAST UPDATE

Issued at 1018 PM EDT Fri Jun 26 2026

Model and ACARS soundings continue to depict a deeply saturated/pseudotropical airmass in place across central Indiana tonight, with near-saturation up through about 450 mb and moist adiabatic lapse rates through the tropopause. Minimal instability is available as a result, with larger values concentrated south of the area where more widespread and stronger deep convection has occurred tonight, in part driven by a remnant MCV.

CAMs depict some additional shower activity and perhaps a rumble of thunder overnight, with chances highest across the south obviously, and have made some PoP adjustments in this respect, though with a lack of more significant upper level support, suspect coverage and intensity will be limited for much of the area. That said, precipitable water values remain near 2 inches, and even showers will be capable of quick heavy downpours. These limited hydrologic concerns will be the primary issue overnight.

Blended in latest short term guidance which keeps temperatures largely steady or very slowly falling a few degrees at most overnight with the boundary moving little, expansive cloud cover, and dewpoints in the mid 60s to low 70s across the area. This bumped the min temps up slightly, primarily central and north.

DISCUSSION (This evening through Friday)

Issued at 319 PM EDT Fri Jun 26 2026

Today through Saturday Night

Quasi-zonal flow aloft above an east-west oriented baroclinic zone will allow a mid-level wave to progress into Indiana this evening. Surface low pressure associated with the wave will allow the baroclinic zone to lift northward as a warm front this afternoon. Numerous showers have developed today, initially from broad isentropic lift but some convective elements have also developed this afternoon. Low-level instability increases with time as the warm and buoyant air mass behind the front advects northward.

Though instability never becomes abundant, it likely becomes at least sufficient for continued scattered convective development into tonight. As the low approaches, model hodographs show some elongation and curvature in the 1-2km layer due to a strengthening low-level jet. Given a temperature profile that shows roughly moist adiabatic lapse rates, relatively shallow convection with minimal lightning is possible today. Despite this, some of these showers/storms may exhibit mesocyclone development due to the low- level shear profile. As such, isolated tornadoes are possible later today into tonight mainly across our southwest where better surface lapse rates are found. Strong wind gusts are also possible if activity can congeal into a line or cluster.

Our primary threat, however, is flooding and heavy rainfall. With deep moisture, moist adiabatic lapse rates, and a deep warm cloud layer, we can expect efficient rainfall processes today. Additionally, hodographs indicate that mature convection could become slow to stationary at times. Very heavy rainfall rates with prolonged duration across already moist ground may lead to a flooding and flash flooding threat through tonight. Additional showers and thunderstorms are possible on Saturday as the low pressure itself sits overhead, though activity will be more isolated in nature. The Flood Watch will be extended until 18z Saturday to account for this.

Convective coverage is a bit uncertain through tonight due to the relatively weak surface forcing as well as a mid-level wave that is weaker on recent model runs compared to earlier ones. Convective- allowing models have a difficult time with storm placement in such situation, and run to run consistency is likely to be quite low.

Sunday into Next Week

A few storms may linger into Sunday morning but the trend will be for the frontal boundary to lift north of the area Sunday as deep ridging expands into the Ohio Valley. This will serve as the transition point towards progressively hotter and more humid conditions that will last through much of next week as the core of the ridge peaks with heights at 596-597dam. Multiple days with highs in the 90s are anticipated with the highest heat indices of the summer so far rising into the 100s during the afternoons. Isolated late afternoon and evening convection may develop by late next week as the mid-level heights begin to fall back. As the upper ridge retrogrades to the southwest 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 (06Z TAF Issuance)

Issued at 1245 AM EDT Sat Jun 27 2026

Impacts:

- IFR or worse conditions through the morning in fog, low ceilings, and scattered showers/perhaps a few thunderstorms

- Conditions improving to MVFR in the afternoon but with scattered convection redeveloping

Discussion:

Poor flying conditions will persist through the morning with only marginal improvement into the afternoon as deep moisture remains trapped over the region in the vicinity of a frontal boundary. Ceilings at 500ft and lower are expected through daybreak with slow lifting by midday. The boundary layer remains saturated however with stratus lingering in the MVFR category through tonight.

The convective threat is messy and chaotic with the boundary remaining in the area. The bulk of the showers through mid morning will remain over southern parts of central Indiana with any impacts being confined especially to KBMG and possibly KHUF. As the atmosphere destabilizes this afternoon...scattered convection will develop and may impact all of the terminals. Showers and storms will likely persist through this evening before gradually diminishing tonight.

IND WATCHES/WARNINGS/ADVISORIES

Flood Watch through this afternoon for INZ051>053-060>065- 067>072.