textproduct: Indianapolis

KEY MESSAGES

- Rain and storms chances return tonight and linger into early next week, with greatest chances Thursday and Friday

- Localized flooding will be possible at times from repeated rounds of convection

- A few strong/severe storms are possible this weekend into early next week...with low confidence on exact details

FORECAST UPDATE

Issued at 937 PM EDT Wed Aug 5 2026

No major changes needed to the ongoing forecast with conditions generally evolving as expected. A weak cluster of storms over Carroll county has dissipated as it exited the area with satellite showing generally warming tops across an area of showers in eastern and northern Illinois. With dry air near the surface and weakening lift as the storms move to the east, expect to see a continued downward trend through the night with showers and storms generally remaining north and west of the forecast area. Much like recent days, temperatures have cooled faster than models have depicted post-sunset but that was well captured already in the forecast.

Fog coverage looks fairly minimal across the area after another well- mixed day today, but favored areas such as river valleys will likely see at least some patchy fog along with shallow corn-field fog.

DISCUSSION (This evening through Wednesday)

Issued at 251 PM EDT Wed Aug 5 2026

Broad upper-level troughing currently resides over the northern CONUS with an embedded shortwave over the northern Plains. Weak and elongated surface troughing induced by the shortwave is also located over the northern Plains. A cold front has slowly been moving southward, triggering convection upstream across Iowa and northern Illinois. Though the front has been advancing towards Indiana, it has slowed in its forward progress today.

Guidance is in fairly good agreement showing this front continuing to slow, or even stall, to our west. Multiple rounds of showers and thunderstorms are depicted by CAM guidance, particularly where the nocturnal low-level jet terminates. This places the most likely area of thunderstorm activity far to our west over Missouri into central Illinois. A large complex of thunderstorms is most likely to develop, moving eastward into a dry air mass with little large-scale forcing. As such, weakening is anticipated with any storm complex that tries to enter Indiana from Illinois.

Nevertheless, repeated rounds of convection over Illinois should allow for atmospheric saturation which may enable shower and storm activity to finally advance into Indiana tomorrow morning. Even if it does, it still looks to be in a weakening state and likely just a remnant area of stratiform rain or showers. With little instability and shear, severe weather is not anticipated through Thursday morning.

Renewed thunderstorm activity is possible on Thursday afternoon but a key mitigating factor may be too much to overcome. This would be the lingering cold pool / stabilization from tonight's convective complex. Most guidance is against the idea of afternoon showers and storms on Thursday. However, a few do show development after sunset Thursday evening as the low-level jet tries to kick in to our southwest.

A very similar situation may unfold on Friday with isolated to scattered showers and thunderstorms. Forcing looks minimal, so confidence is fairly low on coverage.

This Weekend Into Next Week

A semi-active period of weather may develop this weekend into next week as ridging over the intermountain west amplifies, displacing the CONUS trough eastward. Northwest flow takes hold over Indiana with a warm and humid air mass at the surface. Repeated rounds of thunderstorm development upstream could propagate southeastward aided by the upper-level flow aloft. Additionally, nightly low-level jet development could allow for convective maintenance downstream. Uncertainty is still high, however, even if the environment is favorable for MCSs (mesoscale convective systems). This is because forcing in this kind of environment can be fairly weak and nebulous. Pin-pointing exactly where thunderstorms will develop can be tricky, and which clusters become the dominant MCS even trickier. Additionally, subsequent convective development depends on how the previous round of convection altered the overall environment.

AVIATION (00Z TAF Issuance)

Issued at 713 PM EDT Wed Aug 5 2026

Impacts:

- Patchy fog 08Z to 12Z - Occasional MVFR vsbys due to rain after 14Z

Discussion:

VFR conditions expected through the start TAF period with MVFR to potentially IFR fog from 08Z to 12Z. Fog chances will be greatest at HUF and BMG, but may also occur at LAF. Any fog will dissipate quickly after sunrise with increasing mid level clouds after 12Z Chances for showers increase after 14Z with rain initially impacting LAF and HUF. There could be a few rumbles of thunder at times, but expectations are that the lightning will be low in coverage through the day. Winds will generally remain light and variable through 12Z before becoming southerly to southwesterly at 5-10kts through the day.

IND WATCHES/WARNINGS/ADVISORIES

None.