textproduct: Indianapolis

KEY MESSAGES

- Peak heat indices around 100 degrees each afternoon through Saturday

- Greater chance for showers and storms today and Saturday, primarily during the afternoon and evening

- Isolated strong to severe thunderstorms are possible this afternoon and more so Saturday PM, damaging wind gusts are the primary threat

FORECAST UPDATE

Issued at 955 AM EDT Fri Jul 17 2026

The forecast remains in good shape with only minor adjustments made to POPs through the day. A few showers and a stray storm developed earlier this morning with marginal forcing and abundant moisture in place. Look for isolated convection to remain possible during the morning hours before daytime heating promotes more widespread coverage into the afternoon hours.

At least moderate destabilization is expected later in the day with steepening lapse rates. Forecast soundings support this with MLCAPE generally around 2000 to 2500 J/KG and DCAPE values approaching 600 to 800 J/KG which suggest the potential for gusty winds in stronger cells. Most thunderstorms will remain sub-severe given weak deep-layer wind shear, but an isolated damaging wind gust cannot be ruled out. Efficient rainfall rates from warm rain processes may also result in localized flooding if any training occurs.

Canadian wildfire smoke has made its way into portions of central Indiana, primarily across northeastern counties. Increasing southwesterly flow through the day should help to push the smoke further north.

DISCUSSION (Today through Thursday)

Issued at 311 AM EDT Fri Jul 17 2026

A more active pattern is expected going into the weekend with multiple chances of showers and convection.

Temperatures over the next few days will be a few degrees less than the past several, but with increased moisture, still expect heat indices in the upper 90s to near 100 at times. Today will see chances for showers and storms as a mid to upper level disturbance combines with daytime heating within the hot and humid airmass in place. While widespread severe is not expected, can't rule out a few stronger cells producing damaging winds, mainly across our eastern half. Localized flooding could also be a threat, especially if any training occurs.

Another shortwave with an associated cold front will move through central Indiana Saturday, bringing additional convection and slightly better chances of strong to severe cells with damaging winds as the main threat. Forecast soundings depict around 20-30 kt of effective shear, strong destabilization with steep low-level lapse rates, and DCAPE values as high as 1000 to 1400 J/KG which support the threat. The primary convective hazard is damaging wind gusts. Isolated large hail cannot be ruled out either, but the threat will quickly lessen as upscale growth occurs. The main timing appears to be from the mid afternoon through the early overnight hours.

Smoke from Canadian wildfires is also expected to drift into our NE today. This smoke should fully push off to the east by Saturday from the front moving through.

Behind the surface front, a surface high will move into the region with NW flow aloft helping to bring in slightly drier air and a brief break from convection. While models start to diverge for next week, they do show a chance of a shortwave potentially bringing additional rain chances early to mid week followed by cooler and even drier air for mid to late next week.

AVIATION (12Z TAF Issuance)

Issued at 656 AM EDT Fri Jul 17 2026

Impacts:

- Scattered/numerous -SHRA/TSRA this afternoon/early evening

Discussion:

Mainly VFR conditions are expected near central Indiana terminals through the TAF period with possibly periods of generally MVFR 18Z- 23Z amid stronger SHRA/TSRA.

Winds will be calm or light/variable into the morning and then from generally 190-250 degrees sustained at 3-6KT after 16Z outside of stronger cells, with flow closer to 6-9KT at KIND through 12Z Saturday.

IND WATCHES/WARNINGS/ADVISORIES

None.