textproduct: Indianapolis

KEY MESSAGES

- Mostly sunny skies this weekend with seasonable temperatures.

- Patchy fog possible each morning through Tuesday morning.

- Dry conditions persist through Tuesday, with the next chance for rain arriving late Wednesday into Thursday

FORECAST UPDATE

Issued at 951 AM EDT Sat Sep 26 2026

Fog and stratus continue across the extreme northeast forecast area this morning, impacting mainly the Muncie, Winchester, and Anderson areas. The fog/stratus are trying to advect west. However, satellite shows that heating is already beginning to slow or stop the advection with mixing on the western edge.

Otherwise, mid and high clouds continue across the southwest forecast area. Some of the mid clouds are diminishing.

Have upped sky cover in the far northeast and extended the patchy fog mention. These will continue to mix out this morning. Left the southwest as partly cloudy with mostly sunny elsewhere.

Made no changes to high temperatures at the moment, but will continue to monitor in case changes need to be made from the impacts of the aforementioned cloud cover.

DISCUSSION (Today through Friday)

Issued at 254 AM EDT Sat Sep 26 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

Surface high pressure is building southwestward with lingering mid- level cloud cover dissipating as of 3am Saturday. Continued clearing is expected as large-scale subsidence from the high takes hold. A subsident patter continues through the weekend as Indiana is between two systems...one just to our west over the Plains and a nor'easter over the Mid Atlantic.

Overall, clear skies will allow daytime temperatures to trend above guidance with highs in the 70s. Lows on the other hand will be a bit below guidance due to efficient radiational cooling conditions. Low temperatures in the 40s to near 50 are expected each night. Additionally, these conditions are good for fog formation and patchy fog is possible both Saturday, Sunday, and Monday nights.

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 (12Z TAF Issuance)

Issued at 638 AM EDT Sat Sep 26 2026

Impacts:

- Patchy fog possible Sunday morning.

Discussion:

VFR conditions expected through the 08z. Patchy fog with visibility reductions after 08z.

Mid-level cloud cover is beginning to diminish based on satellite trends over the past 2 to 4 hours. Continued clearing is expected through 14z, with a few high clouds persisting into the afternoon.

Winds remain out of the northeast today, between 5 to 10 knots. Speeds diminish overnight potentially becoming light and variable.

Combined with clear skies, light winds may allow patchy fog to develop early Sunday morning. The best chance of fog is at typically fog-prone terminals (LAF, HUF, and BMG). Fog should be shallow but enough to cause brief reductions in visibility. A tempo group has been added at these terminals to account for this potential.

IND WATCHES/WARNINGS/ADVISORIES

None.