textproduct: Indianapolis

KEY MESSAGES

- Warm and mostly dry through Thursday with temperatures well above normal.

- Widespread rain expected Thursday night through Friday AM, QPF amounts ranging from a few tenths of an inch to possibly 1 inch

- Dry and much cooler weather expected over the weekend into next week; potential for first lows to drop into the 30s across portions of central Indiana Tuesday morning

DISCUSSION (This evening through Wednesday)

Issued at 217 PM EDT Wed Sep 30 2026

Latest surface analysis depicts surface high pressure centered near the East Coast while surface ridging extends back into the Midwest. Meanwhile, satellite imagery depicts extensive mid-high clouds from a subtle shortwave moving through aloft and moisture from the remnants of Hurricane Polo streaming in.

ACARS soundings show a dry layer remains in the lower levels across central Indiana from residual subsidence induced dry air. This will likely limit any chance for measurable precipitation, but a few sprinkles are possible over northern portions of the area where there is greater mid-upper level moisture. Less cloud cover across southern counties has allowed for temperatures to warm well into the mid 80s while greater cloud cover further north has kept temperatures generally in the upper 70s to low 80s.

Surface ridging along with lingering subsidence induced dry air in the lower levels will likely allow dry conditions to persist for much of the day Thursday, outside of the potential for a few brief sprinkles. Highs are expected to be well above normal on Thursday due to increasing warm air advection, ranging from the mid to upper 80s.

Thursday night through Friday...

Model guidance generally depicts the remnants of Hurricane Polo getting absorbed into a broad upper level trough moving across the Great Lakes Region later this week. Deep tropical surging northward and sufficient forcing from the merging features supports increasing rain chances. Precipitation is expected to begin as early as Thursday evening across western portions of the area with widespread rain possible Thursday night into Friday morning.

Models have continued to trend towards lower QPF due to overall forcing quickly diminishing as the remnants of Hurricane Polo get absorbed into the upper wave. At this time, it appears most locations should see around 0.25 to 0.75 inches of rain. Localized amounts up to an inch or slightly higher are still possible. Look for an associated cold front to push through Friday morning. Cooler- drier air filtering into the region through the day will support mostly dry conditions by the afternoon and clearing skies. Much cooler highs in the upper 60s to low 70s are expected on Friday thanks to the cooler airmass filtering in.

Friday night through the middle of next week...

High pressure building in Friday night into Saturday will provide quiet weather conditions with partly cloudy skies. Guidance is in good agreement that another cold front associated with an upper wave pushes through around late Sunday. Precipitation is not expected due to limited moisture return ahead of the front, but look for another shot of cooler-drier air.

Highs generally in the mid 60s to low 70s over the weekend are expected to fall into the 60s for all of central Indiana by early next week. Efficient radiational cooling conditions from surface high pressure overhead Monday night could allow for temperatures to fall into the upper 30s across northeastern counties. Patchy frost cannot be ruled out. Surface high pressure shifts east towards the middle of next week allowing for return flow. Large scale subsidence continues to support dry weather while return flow supports warming temperatures.

AVIATION (18Z TAF Issuance)

Issued at 143 PM EDT Wed Sep 30 2026

Impacts:

- Non-convective LLWS is possible tonight through about 13Z Thursday

- Southwesterly wind gusts between 20-25 kt possible on Thursday

Discussion:

BKN-OVC skies are expected much of the period as mid and upper level moisture stream into the area ahead of an approaching frontal system. A few sprinkles cannot be ruled out near LAF, but nothing substantial enough to have an impact is expected. Ceilings will gradually lower during the period, but remaining well into the VFR range, becoming around 8-12kft tonight

Winds will predominately be south/southwesterly, but some brief backing to SE is possible this evening. Expect winds to increase on Thursday with the potential for 20-25 kt gusts during the day.

Non-convective LLWS is possible tonight through about 13Z Thursday as near surface winds remain relatively light and the LLJ strengthens to around 30-40 kt. The LLWS could be around or lower than 1,000 feet and the general direction should be 220-240 degrees.

IND WATCHES/WARNINGS/ADVISORIES

None.