textproduct: Indianapolis

KEY MESSAGES

- Occasional showers/storms this evening into next week

- Localized ponding/flooding of low-lying areas will be possible where repeated rounds of downpours occur

- An isolated strong/severe storm cannot be ruled out...mainly Saturday night into Monday night

DISCUSSION (This evening through Friday)

Issued at 242 PM EDT Fri Aug 7 2026

Today through Saturday night...

A mid-level wave pushing through the region and moderate-strong destabilization will continue to promote scattered convection through the evening. The disturbance is then expected to shift east allowing convection to diminish overnight. Severe weather is not expected due to limited deep-layer wind shear. That said, forecast soundings depict steep low-level lapse rates and DCAPE values up to 1000 J/KG. This could support an isolated strong to severe downburst this afternoon or evening.

Latest CAMs have gradually become less bullish on the threat for a strong downburst. This is likely due to early day convection and clouds limiting limiting destabilization more than initially expected. Very localized heavy rainfall cannot be ruled out either which may result in flooding. Storms will be moving E or ENE around 20-30 mph, but efficient rainfall rates and any brief training could result in localized flooding.

ANother mid-upper level wave and an associated weak front will move in on Saturday. Weak forcing from these features along with moderate- strong destabilization may support isolated convection late in the day. Convective development remains uncertain due to marginal forcing for ascent, but if any strong storm can develop then a strong downburst cannot be completely ruled out given sufficient DCAPE.

Sunday through next week...

Guidance depicts longwave troughing across the region during much of the period with multiple embedded shortwaves moving through within northwest flow aloft. These impulses will promote additional convective chances at times as deeper moisture surges back into central Indiana. Expect daily rain and storms chances with low confidence on exacts details due to varying model solutions regarding the low amplitude shortwaves passing through. The greatest precipitation chances are from late Tuesday through Wednesday when the strongest forcing and deeper moisture overlap.

Some guidance is already hinting at MCSs or storm clusters developing upstream and propagating towards Indiana at times. Look for higher uncertainty regarding specific details of each subsequent round of convection. The evolution of previous day convection could significantly impact the forecast. In general, models depict strong destabilization most days and enhancement of mid-upper level flow from the passing waves. This could potentially support isolated severe thunderstorms somewhere near the region, but expect confidence to remain low until models become better aligned. Localized flooding from repeated rounds of convection and damaging wind gusts would likely be the primary threats from this setup.

It is worth noting CSU ML severe probabilities have increased gradually over the past few days and generally highlight the Sunday through Wednesday timeframe with at least low probabilities. Expect increasingly warm and humid conditions late this weekend into early due to warm air advection. The highest heat indices are expected on Monday when they could peak near 100F across much of central Indiana. These peak heat indices may not be reached if convection moves through earlier in the day.

AVIATION (18Z TAF Issuance)

Issued at 1253 PM EDT Fri Aug 7 2026

Impacts:

- VFR cigs this afternoon and early evening amid ISO-SCT -SHRA - MVFR visibilities possible overnight

Discussion:

A warm and moist air mass across Central Indiana with some weak forcing aloft will allow for showers and perhaps a thunderstorm to develop this afternoon and into the evening. ACARS soundings shallow CAPE available near 1700 J/KG. This will be sufficient for shra/tsra development due to diurnal heating. HRRR shows scattered convection developing across the area after 20Z, persisting until 02Z. Morning clouds have delayed convective initiation, but GOES19 shows a bit more clearing to the west should allow for heating to proceed within the next couple of hours.

After convection ends this evening, a return to VFR is expected, but dew point depressions overnight remain small amid light winds which will be an ideal recipe for MVFR fog development.

IND WATCHES/WARNINGS/ADVISORIES

None.