textproduct: Indianapolis

KEY MESSAGES

- Hot and humid through at least mid week next week

- Daily chances for showers and storms

- At least an isolated severe threat at times Sunday into late Wednesday, with damaging winds and localized flooding the primary threats

FORECAST UPDATE

Issued at 1025 PM EDT Sat Aug 8 2026

No significant changes required to going forecast this evening. Quiet night is in store with modestly cooler conditions than recent nights as slightly lower surface dewpoints slowly push into the area.

Light winds and mostly clear skies will set the stage for fog, which could become dense in spots late tonight. Grids already have a mention, and will monitor trends through the night and adjust as needed. Near term guidance is inconsistent and does not appear to be capturing fog potential very well, which lends lower confidence to what is by its nature frequently a low confidence variable.

DISCUSSION (This evening through Saturday)

Issued at 239 PM EDT Sat Aug 8 2026

Rest of This Afternoon and Tonight...

A weakening cold front will continue to sink into the area into tonight. Temperatures in the middle 80s to around 90 combined with dewpoints in the lower to middle 70s have aided in creating MLCAPE values between 2000-3000 J/kg. However, shear is weak. Although the front doesn't have any upper support, it might be able to tap into the instability and generate some isolated convection.

Will continue with mainly slight chance PoPs (isolated wording) into early this evening as the front stalls out in the area. With the lack of shear, severe storms are not expected.

Overnight, light winds and mostly clear skies will allow some fog to develop across the area. Widespread dense fog looks unlikely, but favored areas may see brief dense fog.

Slightly cooler air behind the front will allow the far northeast forecast area to get low temperatures in the lower 60s, but most areas will be in the mid 60s to around 70.

Sunday and Sunday night...

Fog will mix out early Sunday morning. Otherwise, Sunday morning will be quiet. Sunday afternoon, remnant thunderstorms or new thunderstorms created from outflow from remnant thunderstorms to the west of the area may move in/develop. Best forcing will be north of the area, so kept PoPs no higher than the chance category and near/ north of I-70. Confidence is low in coverage not only because the best forcing will be north of the area, but also whether outflow from the storms may spark additional storms to the south.

Sunday night, more convection will develop northwest of central Indiana on the nose of an 850mb jet and with some upper energy. These storms will move southeast and may get into the northern forecast area. Will have some low PoPs there. Will have to watch and see if the storms can build farther south than expected.

Shear will be better on Sunday, so some isolated severe storms are possible, mainly north.

Sunday will be hot and humid, with heat indices approaching 100 degrees across the south.

Monday onward...

An upper level high/ridge will remain to the west and south of central Indiana through much of the period. Energy riding around the high will bring forcing to the area at times. Meanwhile, at the surface, a front will meander in the vicinity.

For much of the week, ample moisture will be in place. Surface dewpoints will be in the 70s. Forcing from upper energy and the surface front will produce scattered to numerous showers and thunderstorms at times into next weekend.

Strong instability should be able to build at times into mid-week next week, and shear will increase at times. These will keep the threat for severe weather around at times into mid-week next week. The primary severe threat looks to be damaging winds. The plentiful moisture content of the atmosphere will also keep heavy rain and localized flooding a threat.

However, uncertainty on the timing and strength of the upper energy moving around the upper high leads to uncertainty on timing and coverage of severe storms. For now, the threat looks to gradually shift south across the area into mid-week next week as the upper ridge gets pushed farther south.

Late week next week into next weekend, the threat for convection will continue, but with some milder air sneaking into the area, instability will be lower, leading to a lower severe threat.

Looking at temperatures, the proximity of the upper high will lead to hot conditions early next week, with highs around 90. Lows will only be in the 70s. With the dewpoints in the 70s, heat indices will be around 100 degrees. Heat Risk may reach the Moderate category for parts of the area on Monday and Tuesday. Of course, the aforementioned thunderstorms could easily impact how warm it gets, adding to the uncertainty. Will have to watch for the potential for a Heat Advisory Monday and Tuesday, mainly south where the warmer temperatures and lower chances for rain will be.

Temperatures will moderate into the end of next week, with highs in the upper 70s to lower 80s expected.

AVIATION (00Z TAF Issuance)

Issued at 753 PM EDT Sat Aug 8 2026

Impacts:

- MVFR and worse fog possible overnight

- Low chance for showers/storms at the end of the period, mainly at LAF and IND

Discussion:

Winds will be dropping off early in the period. Lingering low level moisture and light winds will lead to areas of fog overnight, with MVFR and worse conditions possible. KIND should remain VFR. Fog will mix out early Sunday.

Southerly winds are expected to pick back up tomorrow and could see gusts nearing 20 kts in the afternoon, mainly at LAF and IND. Otherwise sustained winds near 10 kts is expected. Afternoon to evening storms are also possible tomorrow, mainly further north, so have included VCSH at LAF and IND for the end of the period.

IND WATCHES/WARNINGS/ADVISORIES

None.