textproduct: Indianapolis

KEY MESSAGES

- Quiet weather with near normal temperatures today and tonight

- Showers and thunderstorms return late on Friday and continue through the weekend. There is an excessive rainfall threat Friday night through Saturday for most of central Indiana.

- Warming trend likely for the first week of August

FORECAST UPDATE

Issued at 1001 AM EDT Thu Jul 30 2026

No changes needed to the forecast this morning. Sunny skies have allowed for efficient boundary layer mixing this morning. Because of this, we are expecting temperatures to be a bit above guidance while dew points fall slightly below. More weight will be added to short- term guidance like the HRRR owing to their improved PBL mixing schemes. Overall, expect a quiet and seasonably warm day today.

DISCUSSION (Today through Wednesday)

Issued at 237 AM EDT Thu Jul 30 2026

High pressure remains the predominant feature for today and tonight as confluence aloft continues to build pressure through the lower troposphere. The center of this surface high is expected to track just to the north of central Indiana of which should lead to a light easterly winds throughout the day. Low level cloud cover should be fairly minimal throughout the day due to the ongoing subsidence, but a few diurnal cumulus may be possible as upward latent heat fluxes help provide some moisture to the PBL. Aloft, moisture within an upstream mid level trough feature will likely be kicked into the jet stream, with scattered cirrus clouds expected over central Indiana by mid afternoon.

850mb temperatures will be the same today as yesterday, with surface temperatures expected to respond accordingly; given the slightly drier near surface air, afternoon highs will likely push a bit higher with the current expected highs between 84-86F. The only hazard of concern for today and tonight will be some potential for fog development near the pressure center over N/NW portions of the area. A majority of the fog should be contained to low lying valleys and well irregated farmland, but this may advect elsewhere depending on depth of any fog layer.

As mentioned, a mid level trough feature will continue to develop throughout the day, mostly due to ongoing super-geostrophic flow over the Rockies aiding in pressure falls over the western Missouri Valley. Due to the placement of the jet, much of the pressure depletion will be due to very strong diffluence and thus weak steering flow with a majority of the ensemble members showing the mid level low becoming detached from the flow aloft. The initial rain threat is expected to be Friday late afternoon into the evening along an elongated confluence band as the low pushes eastward. Any rain on Friday afternoon and evening should be mostly light, but a few elevated convective cells will be possible leading to a larger range in QPF outcomes.

For Friday night through Saturday, forecast confidence starts to wane. While ensemble members agree on the overall pattern, the path and the strength of the cutoff low have varied some over the last few runs due to the lack of strong dynamics. Latest trends have shifted the center of the flow further north, nearing southern portions of the area on Saturday. Due to the weak steering flow but abundant upward lift near the cutoff low, near stationary and training convection may be possible at times Friday night through Saturday leading to an excessive rainfall threat over most of the area. While an isolated damaging wind gust cannot be ruled out throughout this event, weak low level lapse rates and bulk shear will limit the severity of most thunderstorm. The best chance for any severe wind gusts will be on the east to southeast side of the low where the LLJ is a bit stronger, helping create bulk shear values closer to 30kt.

For next week, there are not any strong signals within the 300mb pattern leading to fairly high uncertainty on precipitation. However, regarding temperatures, the polar jet looks to be well displaced to the north, with should allow for above average 850mb temperatures and therefor some likelihood of above average surface temperatures.

AVIATION (12Z TAF Issuance)

Issued at 550 AM EDT Thu Jul 30 2026

Impacts:

Impacts:

- Patchy fog at KLAF through 13Z

Discussion:

Mostly clear skies and lighter winds are expected this morning. This has led to some patchy fog development mainly at KLAF. This has been kept through 13Z, with and fog expected to dissipate after. Winds will generally be out of the east today less than 10kt. Calm winds are expected overnight before switching to southerly tomorrow morning.

This afternoon, some diurnal cu is possible at the southern 3 sites. SCT cirrus at 25kft is likely to move in from the northwest late this afternoon through tonight.

IND WATCHES/WARNINGS/ADVISORIES

None.