textproduct: Indianapolis

KEY MESSAGES

- Heat Advisory through 9PM this evening

- Scattered to numerous thunderstorms will continue through the evening, with lower coverage overnight into Sunday

- Damaging winds and heavy downpours will be the main threats through this evening

- Trending cooler into next week with frequent chances for showers and storms

DISCUSSION (This evening through Saturday)

Issued at 222 PM EDT Sat Jul 4 2026

Rest of This Afternoon into This Evening...

An old boundary was near Interstate 70 early this afternoon. Cumulus were developing near and along this boundary. Meanwhile, an MCV was moving into northern Illinois. With continued hot and humid conditions, MLCAPE was approaching 2000 J/kg. Shear was weak.

Scattered thunderstorms may develop along the old boundary, while convection had already developed in Illinois in advance of the MCV. Expect the most coverage of convection to be associated with the MCV and focused on the northern half of central Indiana. However, will also have to monitor how coverage of convection in southern Illinois develops.

Severe convection is possible given the instability, with downbursts possible with the scattered convection not associated with the MCV. The MCV influenced convection could become more organized and form a cold pool. This will increase the threat of damaging winds with these.

Present indications are that the highest severe threat and most coverage will be 22-02Z (6PM to 10PM EDT).

Will go likely PoPs across the northern half or so of the forecast area with the best forcing from the MCV and go lower PoPs to the south.

Temperatures have yet to reach 90 this afternoon, but with heat indices still approaching 100 and with a lot of people outside today, will continue the Heat Advisory as is.

Overnight tonight through Sunday night...

Some weak forcing will continue overnight so kept some chance PoPs around. Severe weather is not expected with diminished instability. With extra particulates in the air tonight and humid conditions, patchy fog is likely overnight. Lows will be in the mid 60s to around 70.

An upper trough and weak surface front will be across the area on Sunday, so scattered showers and thunderstorms will continue. Highest coverage will be in the afternoon. More clouds will be around on Sunday, and high temperatures will be cooler. Highs will be in the lower to middle 80s. Instability will be weaker Sunday, so severe storms are not expected.

Rain chances will diminish Sunday evening as heating is lost.

Monday...

Upper troughing will linger across the area on Monday so kept some slight chance to chance category PoPs around. Temperatures will peak in the lower and middle 80s.

Tuesday and Wednesday...

Part of the upper ridge will try and sneak back into the area. High pressure will be in control at the surface for most areas. Thus, dry conditions are expected, with temperatures returning to the middle and upper 80s.

Thursday and beyond...

Upper flow will become northwest with upper waves moving through the flow. This will bring a return of daily chances for showers and thunderstorms. A surface cold front will move into the vicinity around Friday as well.

Questions remain on the timing and strength of the upper waves and on the timing of the cold front. Will have PoPs each day, but confidence is low on timing of the highest PoPs.

Temperatures in the middle and upper 80s Thursday should give way to the lower and middle 80s by Saturday, but this may change depending on the timing of the surface front.

AVIATION (18Z TAF Issuance)

Issued at 140 PM EDT Sat Jul 4 2026

Impacts:

- Scattered to numerous convection, with most coverage 22-02Z - MVFR visibility in fog likely overnight. Stratus is possible.

Discussion:

Scattered convection is likely to develop early in the period, with a leftover boundary near KIND and convection already in eastern Illinois. Better odds for convection will come late this afternoon and into the evening with an upper level feature. Lingering scattered convection will persist into the overnight.

MVFR fog will develop overnight. Some guidance also has low MVFR/high IFR ceilings in stratus developing, but confidence wasn't high enough to include at this time.

IND WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 9 PM EDT this evening for INZ021-028>031- 035>049-051>057-060>065-067>072.