textproduct: Indianapolis

KEY MESSAGES

- One more round of showers and a few storms early today

- Areas of fog tonight with dense fog possible

- Additional thunderstorms likely mid week

- Turning milder and drier late week into next weekend

FORECAST UPDATE

Issued at 847 AM EDT Mon Aug 17 2026

Surface analysis continues to show a trough of low pressure in our region. The trough was found over Nrn OH and Nrn Indiana, before diving SW across Indiana to western TN and Arkansas. GOES19 shows a dying convective cluster in SE Indiana and KY and rain associated with this system had exited east. Radar shows a few showers ahead of the trough across Central Indiana stretching from a near MIE-HUF line. Although the showers were moving along, brief heavy rain rates, of 2-4 inches per hour will be possible. Water Vapor shows a significant change today. There are breaks within the ever persistent tropical plume that has been streaming over Indiana. Today the plume is only streaming across NM and into KS, while subsidence was providing drying across IL/MI and drifting toward Indiana. Dew point temperatures remained quite high across the state in the lower 70s.

This afternoon, skies will become partly sunny as morning stratus slowly burns off and high debris clouds from the convective cluster subside and drift east. As the trough sags southward across Indiana this morning and early afternoon, a few isolated showers and storm will still remain possible as we are seeing on radar. With the very moist air mass in place brief heavy rains will be possible. Time heights and HRRR continue to keep cloud cover around through the morning, but show some breaks by afternoon. Thus will continue to keep skies mostly cloudy/becoming partly sunny this afternoon, with isolated showers and storms possible. Clouds will help to keep temperatures from rising. Highs will only reach the lower 80s.

DISCUSSION (Today through Sunday)

Issued at 240 AM EDT Mon Aug 17 2026

The persistent upper level ridge to the south that has kept central Indiana squarely in the bullseye of ring-of-fire convection for the last week plus will finally begin to retrograde to the west and amplify this week.

A cold front to the northwest will push through the area today, with scattered pre-frontal showers and storms early in the day, primarily across the southern portions of the area. Rain chances will finally come to an end late today as the tail end of the boundary exits the area, with dry weather expected tonight into Tuesday as surface high pressure pushes into the region.

Light to calm winds, clearing skies, and very moist ground will likely produce areas of fog tonight despite the decreasing dewpoints. Dense fog will definitely be on the table given how incredibly waterlogged most of the area is.

The next chance for thunderstorms will come late Tuesday night into Wednesday night as one or more shortwave disturbances pivoting around a large upper low over the eastern Canadian provinces drives another frontal boundary through the area. Heavy rain and strong to severe storms will again be a threat, as though instability is a bit more modest owing to more limited moisture (though still 70th-80th percentile climatologically), deep layer shear should be fairly robust. Damaging winds would be the primary threat with this activity, with at least a modest flash flood threat given the extreme antecedent conditions.

The more amplified pattern looks to persist late week into early next, with below normal temperatures and mostly quiet weather appearing likely, though an occasional upper level disturbance in the cyclonic flow aloft may necessitate a slight chance of a shower.

AVIATION (12Z TAF Issuance)

Issued at 841 AM EDT Mon Aug 17 2026

Impacts:

- Chance for showers and thunderstorms early in the period

- IFR/MVFR ceilings this morning, possibly into the early afternoon hours

- Patchy fog overnight

Discussion:

Scattered showers and a few embedded thunderstorms are possible this morning at HUF, IND, and BMG. Patchy drizzle has been observed as well with reduced ceilings and visibility. IFR conditions are likely this morning until a cold front passes through allowing for gradual improvement.

Northwesterly flow takes hold behind the front this afternoon. A few gusts at IND are possible in the afternoon. Winds will become light and variable to calm after 00Z tonight, with areas of fog possible as high pressure builds into the region.

IND WATCHES/WARNINGS/ADVISORIES

None.