textproduct: Indianapolis

KEY MESSAGES

- Cloud cover gradually decreases through tonight with mostly clear skies for the weekend - Dry conditions persist through Tuesday, with the next chance for rain arriving Wednesday into Thursday

DISCUSSION (This evening through Friday)

Issued at 128 PM EDT Fri Sep 25 2026

Overview.

High pressure will dominate central Indiana weather into early next week, driving a trend toward clearer skies and warmer temperatures. Low clouds will erode through Saturday morning, giving way to abundant sunshine and daytime highs reaching the lower 80s by Monday. A cold front will approach from the northwest late Tuesday, bringing the next likelihood of showers and thunderstorms before temperatures cool back toward seasonal averages late in the week.

Rest of Today Through Sunday.

Synoptically, central Indiana remains sandwiched between a strong low pressure system off the East Coast and broad ridging across the Great Lakes. This continues to keep surface and near surface flow northeasterly across the area with high clouds from a system to the northwest streaming in aloft. These high clouds along with CAA near the surface will help to keep temperatures cool through the remainder of the day with some signs that the northeastern counties, which started cooler, may struggle to rise out of the low 60s. Tonight, temporal differences in cloud clearing will dictate minimum temperatures; areas in the northeast where clearing occurs earliest will drop into the mid-to-upper 40s due to effective radiational cooling, while western counties hold in the lower 50s. On Saturday, lower cloud cover combined with weaker CAA should allow for warmer temperatures with highs more towards the low to mid 70s.

The broader synoptic pattern remains fairly similar going into Sunday with the aforementioned low pressure system along the East Coast remaining largely locked in place while the ridging across the Great Lakes and system to the west become less pronounced. Surface flow will remain northerly to northeasterly but will be light, which combined with another day of abundant sunshine will keep temperatures in the low to mid 70s.

Monday Through Friday.

The extended period opens with weak upper-level ridge amplification across the eastern CONUS as surface high pressure shifts toward the Mid-Atlantic coast. Both deterministic GFS and ECMWF along with their respective ensemble suites depict strong low-level warm air advection developing across the Mississippi and Ohio Valleys as the low off the East Coast finally begins to push off to the northeast.

Southerly flow early next week doesn't look quite as robust as it did in recent model runs which will keep highs more towards the mid 70s vs lower 80s. This begins to shift towards Wednesday as the synoptic pattern begins to shift. Late Wednesday into Thursday a progressive upper-level trough traverses the Northern Plains and Great Lakes. Deterministic guidance indicates a surface cyclone tracking northeast into the Upper Midwest, pulling a trailing cold front toward central Indiana late Wednesday into Thursday which is about 12-18 hours slower than previous model runs.

Strong synoptic-scale forcing via PVA and a developing 35-45 kt low- level jet will foster moisture transport, elevating PWAT values toward 1.50 inches. Ensemble consensus supports increasing PoPs beginning late Wednesday for showers and scattered thunderstorms along with a lower-end potential for a few strong to severe storms. Post-frontal cold air advection behind the frontal passage will break the warm trend, returning temperatures to near seasonal normals in the upper 60s and lower 70s going into Friday.

AVIATION (18Z TAF Issuance)

Issued at 128 PM EDT Fri Sep 25 2026

Impacts:

- None.

Discussion:

Mid and high clouds will continue to stream into central Indiana into the overnight hours, gradually becoming less diffuse going into Saturday morning. There could be a few areas of low stratus/fog, but those look to be northeast of the terminals. Winds will remain northeasterly through the TAF period at 5-8kt today and tomorrow and around 3-5kt tonight.

IND WATCHES/WARNINGS/ADVISORIES

None.