textproduct: Indianapolis

KEY MESSAGES

- Flood Watch through Saturday morning 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

DISCUSSION (Today through Thursday)

Issued at 255 AM EDT Fri Jun 26 2026

Convection continues to develop in advance of a mid level wave over the mid Mississippi Valley this morning...expanding east across southern Illinois and into the lower Wabash Valley. Embedded cells are dumping in excess of an inch an hour in spots but at least to this point at 06Z...the heaviest totals have remained just south of the forecast area. Temperatures ranged from the mid 60s to the lower 70s.

Quasi-zonal flow aloft in tandem with a stagnant frontal boundary over the Ohio Valley will provide for multiple opportunities for showers and storms through Saturday night. Storms will carry a renewed concern for flooding later today into tonight as a surface wave rides along the boundary and across the region. The front will be forced north of the region by Sunday with the upper level regime transitioning to a broad ridge over the Mississippi and Ohio Valleys. This will resulting in an extended period of hot and humid weather through next week likely resulting in the hottest days of the summer to date.

Today through Saturday Night

The ongoing convection from southeast Missouri northeast into southwest Indiana should continue to expand over the next several hours in response to stronger 850mb flow nosing into the Ohio Valley. The presence of a southwesterly component to the low level flow supports potential backbuilding of convection and training cells through daybreak that will carry a short term flood threat focused especially across the lower Wabash Valley. PWATs will gradually nudge up as well in response to a surge in moisture advection into the area from the southwest. Showers will expand northeast across the forecast area from just before daybreak through much of the morning.

Coverage and intensity of convection will tick up into the afternoon as a surface wave approaches from the west. A remnant MCV associated with the convective cluster over eastern Kansas early this morning will move into the Ohio Valley by the afternoon. This feature presents a wild card introducing a conditional severe weather risk in addition to the flooding concerns for several hours later today focused over southern portions of the forecast area. An increase in low level shear and helicity within the lowest 1 to 2km could be sufficient in concert with weak instability up to around 1000 j/kg to carry a threat for damaging winds and a few tornadoes within stronger cells by late day. The tropical nature of the airmass highlighted by a deeply saturated column...dewpoints in the lower 70s and LCLs below 1000m also offers some historical context locally with the MCV in the area to create potential mischief for cells to rotate in the near surface layer. That being said...the expected thick stratus into the afternoon will serve as a limiting factor to convective intensity. At this time...greatest concern would be from mid afternoon into the early evening across far southern portions of the forecast area south into Kentucky...with higher impacts very likely south of the forecast area where better surface heating will be present.

The heavy rainfall and potential for flooding remains the primary concern for later today however. Gradual strengthening of the low level jet in advance of the surface wave will continue to pump a rich fetch of moisture into the region with PWATS rising above 2 inches over southern counties by mid afternoon. This along with freezing level rising to near 15kft are suggestive of warm rain processes and highly efficient rainfall from convection into the early evening as the low passes through. Am becoming concerned though that the flood threat will not be over once the low passes as CAMs are starting to pick up on renewed convective development over the southern half of the area into the overnight along the remnant frontal boundary. Strengthening of the low level jet oriented to the west-southwest tonight increases the potential for backbuilding and training of convection in the vicinity of the boundary before shifting south closer to the Ohio River by daybreak Saturday.

With the trends noted above and considering the recent wet conditions across the southern portions of the forecast area...have extended the Flood Watch east to encompass the rest of the southern third of the forecast area. High confidence exists in a widespread 1 to 3 inches with locally higher amounts across the Watch area by Saturday morning.

The convective focus is likely to shift closer to the Ohio River initially on Saturday as the boundary drifts in that direction but it will start to pull back north later in the day as ridging aloft amplifies to our west. This will unfortunately pull convection back into the waterlogged portions of the southern forecast area Saturday afternoon and evening and could renew flooding concerns. In addition...a subtle wave traversing overtop of the expanding ridge may generate a convective cluster diving southeast into parts of the area Saturday night. This may require an extension in time to the Flood Watch that will be revisited later today or tonight.

Sunday into Next Week

A few storms may linger 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 back 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 1227 AM EDT Fri Jun 26 2026

Impacts:

- Rain spreading across the area towards daybreak

- Numerous showers throughout the day with thunder possible as well during the afternoon and early evening

- Poor flying conditions developing shortly after daybreak and persisting through tonight

Discussion:

Most of the convection has diminished across central Indiana early this morning with rain and storms confined to the lower Wabash valley and points to the south and west in the vicinity of a stagnant frontal boundary. Convection over the mid Mississippi Valley will lift northeast towards the region during the predawn hours and overspread the terminals after 09Z through mid morning. MVFR stratus will accompany the showers with ceilings steadily dropping throughout the morning.

The approach of a surface wave as the boundary oscillates back into area will bring numerous showers and scattered thunderstorms for the afternoon with the potential for IFR and lower visibilities briefly within any convection that impacts the terminals. Showers should become more scattered in coverage tonight as the front lingers over central Indiana in the wake of the surface low moving away to the east. IFR ceilings will persist through the afternoon and likely through tonight as well.

Light and variable winds early this morning will largely transition to E/SE for much of the day with the possibility of more chaotic wind directions this evening as the low passes through the area.

IND WATCHES/WARNINGS/ADVISORIES

Flood Watch through Saturday morning for INZ051>053-060>065- 067>072.