textproduct: Indianapolis

KEY MESSAGES

- Dry through Monday but upper level smoke will be over the area

- Growing concern for numerous strong to severe thunderstorms with heavy rainfall late Monday night into Tuesday

- Noticeably cooler and less humid for the second half of the week

DISCUSSION (This Evening through Sunday)

Issued at 146 PM EDT Sun Jul 19 2026

Hazy conditions with a milky sky this afternoon as the elevated smoke layer from the Canadian wildfires has settled south across central Indiana. Temperatures at 1730Z were mainly in the upper 70s and lower 80s with lower humidity levels as well.

A drier and slightly cooler airmass will remain across the region through Monday as high pressure passes through the Great Lakes. Return flow will pull moisture back north into the Ohio Valley Monday night ahead of a cold front with increasing signals for a convective cluster producing heavy rainfall and possibly severe weather to move across the area late Monday night into Tuesday. In the wake of this feature...noticeably cooler and less humid air will advect into the region for the middle and latter part of the week.

Rest of This Afternoon through Monday

Air Quality Alerts remain in effect for all but far southern portions of central Indiana through Monday to account for the ongoing smoke impacts. A continued N/NE flow into this evening will become light and variable maintaining the smoke layer over the region but as return flow develops on the back side of the high pressure Monday...improvements are expected in visibility and conditions from the southwest as the bulk of the smoke shifts back to the north into the Great Lakes.

Monday Night and Tuesday

With the upper ridge focused back west across the Rockies and central Plains...northwest flow aloft will develop into Monday as the Ohio Valley and Great Lakes reside on the periphery of the ridge and in an increasingly susceptible location for convective impacts by Monday night. The presence of the high in the area through late day Monday will maintain dry conditions but focus will shift to a strong upper wave riding over the top of the ridge across southern Canada. This feature will dive southeast across the Great Lakes Monday night in tandem with a surface low over James Bay and an associated cold front extending back into the upper Midwest. Confidence continues to increase in an MCS developing to our northwest and diving towards the region Monday night.

While there remain differences with respect to the actual evolution and track of a convective cluster...the presence of a surface wave along the boundary will promote an enhancement of speed and directional shear in addition to higher SRH values across the lower Great Lakes. Timing will be a factor in whether severe convection will make it into the forecast area and if so how far...but the greatest risk from an MCS moving into the region will be damaging winds especially if a mature cold pool develops. The increase in shear and SRH however would put all severe risks in play with a primary focus over northern parts of the forecast area. The orientation and strength of the low level jet in tandem with a rapid influx of deep moisture and PWATS near 2 inches supports heavy rainfall and flooding concerns as well and this may end up becoming the main impact with the potential of a late night/predawn timing early Tuesday. Rainfall rates will be efficient with the freezing level near 15kft. Still details to be worked out but potential for impactful convection late Monday night and early Tuesday continues to grow.

The timing and extent of the overnight/early morning convection will have a direct impact on what takes place during the day Tuesday with the cold front across the area. In the wake of the convective cluster...significant uncertainty exists regarding the degree of destabilization as there is potential for an extended period with leftover cloud debris limiting heating. Considering the kinematic environment...any redeveloping convection along the front would carry an inherent severe risk. The most likely scenario however is that the greatest potential for severe weather will be to the southeast of the forecast area Tuesday afternoon and evening. Any convection will depart central Indiana Tuesday evening as high pressure takes over with a cooler and drier airmass.

Wednesday through Sunday

A broad upper level trough will settle across the eastern pat of the country for the second half of this week as the core of the heat ridge remains centered over the High Plains. With a large area of high pressure dropping out of the Canadian prairies behind the Tuesday cold front...noticeably drier and cooler air will expand across the region and provide a break from the humidity and storms of late. Highs will remain in the mid and upper 70s over much of the forecast area Wednesday and Thursday with comfortable overnight lows into the 50s.

Return flow will develop as the high shifts east by Friday with some potential for convection to track through the Ohio Valley in tandem with an upper level wave. High pressure will reestablish in its wake with dry and seasonable weather next weekend as highs return to the mid and upper 80s by Sunday.

AVIATION (18Z TAF Issuance)

Issued at 1146 AM EDT Sun Jul 19 2026

Impacts:

- MVFR haze due to smoke aloft this afternoon and evening - Patchy fog at outlying terminals early Monday with additional haze at all sites after sunrise

Discussion:

Smoke has settled across the region from the wildfires in Canada... with 4-5SM visibilities in haze across a wide area. This is likely to continue through the afternoon with potential for subtle improvements this evening towards sunset. With mainly clear skies and light winds tonight...patchy fog will develop at the outlying sites in the predawn hours. This will mix out into a general haze once again Monday morning although as return flow developed through the day from the south...the bulk of the smoke aloft will shift back to the north of the region.

IND WATCHES/WARNINGS/ADVISORIES

None.