textproduct: Indianapolis

KEY MESSAGES

- Showers diminishing during the day today

- Damp and dreary today

- Much cooler temperatures for the first half of the week, gradually warming back to near normal levels by next weekend

FORECAST UPDATE

Issued at 920 AM EDT Mon Sep 21 2026

Widespread rain now across eastern Indiana and western Ohio with scattered lighter showers in its wake. Noticeable change in the airmass with cool and breezy northeast winds and temperatures largely in the upper 50s and lower 60s over all but far southern portions of the forecast area at 13Z.

Remnant MCV showing up nicely on the radar over the western forecast area this morning. This feature will continue to press east over the next several hours and should be out of the forecast area by 18Z. There remains potential for additional scattered convection to develop in association with the MCV for the rest of the morning... but an overall trend towards decreasing rainfall coverage has already started and will continue into the early afternoon.

The rest of the day will certainly have an early Fall feel as lower stratus remains in place trapped by a boundary layer inversion and northeast winds continue leading to a damp and dreary day. Highs will largely hold in the mid and upper 60s north of Interstate 70 with 70s further south.

Zone and grid updates out.

DISCUSSION (Today through Sunday)

Issued at 258 AM EDT Mon Sep 21 2026

Early This Morning...

The surface front has moved south of central Indiana, but a couple of upper impulses along with a surface wave riding along the front are bringing enough forcing for numerous showers and some thunderstorms to move into the area.

This forcing will continue through the predawn hours, so have gone with higher PoPs over much of the area. For much of the area, CAPE is elevated with an inversion closer to the surface. Will have to watch the far south where better instability remains closer to the surface, but odds for any severe weather remain low. Heavy rain and localized flooding will be the threats as some training of cells may occur.

Today and Tonight...

At 12Z, rain from one of the upper impulses will likely still be ongoing for parts of the area. Will go likely PoPs for portions of the east and southeast early in the period. Some of the latest hourly guidance is showing another upper impulse generating more numerous showers moving west to east during the morning. Not confident enough yet to up PoPs elsewhere at this time, but will keep an eye on how things develop.

Otherwise, chances for rain will diminish during the day as overall forcing exits. Will have most areas dry by 21Z.

Moisture will be trapped below an inversion so will keep skies mostly cloudy. With the clouds and cooler air behind the front, highs will only reach the middle 60s far northeast to near 80 far southwest.

Clouds will continue to hang around tonight. Lows will be in the 50s.

Tuesday and Wednesday...

A weakening upper low will approach the area on Tuesday. Forcing will be weak, so for now have not gone with any mentionable PoPs. However, wouldn't be surprised to see some isolated showers develop during the afternoon.

The upper low will be east of the area on Wednesday. Most forcing will be east of the area, but an isolated shower is possible in the extreme east during the afternoon.

Lingering moisture will keep skies mostly cloudy on Tuesday, with western areas seeing some partial clearing on Wednesday. Highs will generally be in the upper 60s to middle 70s.

Thursday and beyond...

Surface high pressure will keep the weather quiet during this period. Temperatures will remain below normal into the first part of the weekend, then readings may return to above normal (highs around 80) by next Monday.

AVIATION (18Z TAF Issuance)

Issued at 1233 PM EDT Mon Sep 21 2026

Impacts:

- Predominant MVFR ceilings expected through much of the period. IFR at times early this afternoon and again late tonight primarily at KBMG - Gusts near 20kt possible through the afternoon, mainly at KLAF

Discussion:

Showers have largely shifted east of central Indiana early this afternoon but plentiful low level moisture lingers and is trapped beneath an inversion. This will ensure low stratus goes nowhere over most of the next 24 hours. Ceilings will reside in the MVFR category this afternoon before potentially briefly breaking out to low VFR levels for a few hours this evening. Strengthening of the inversion late tonight will aid in ceilings slipping back to between 1000- 2000ft with the possibility of IFR ceilings at KBMG. Low ceilings will continue on Tuesday.

Northeast winds will continue through the forecast period. Periodic gusts to around 20kts are expected at KLAF this afternoon... otherwise will see a steady 10-15kt wind at all terminals.

IND WATCHES/WARNINGS/ADVISORIES

None.