textproduct: Indianapolis

KEY MESSAGES

- Mostly sunny early this week with warming temperatures.

- Patchy fog possible Monday and Tuesday mornings.

- Dry conditions persist through Wednesday, with the next chance for rain arriving Thursday and then continuing into the weekend.

DISCUSSION (This evening through Sunday)

Issued at 215 PM EDT Sun Sep 27 2026

Rest of This Afternoon through Tuesday...

Subsidence on the west side of the upper low on the east coast of the USA along with surface high pressure will continue to provide dry and quiet weather for central Indiana.

Mainly some passing high clouds are expected, especially across the western forecast area. Good radiational cooling will occur tonight and Monday night, so have cut blended guidance's temperatures both nights. These conditions will allow for patchy fog once again late tonight/early Monday and late Monday night/early Tuesday.

With the dry atmosphere in place and plentiful sunshine expected, raised Monday's and Tuesday's highs from blended guidance.

Wednesday through Next Weekend...

A northern stream upper trough will move through Canada and the Great Lakes into Friday, and this will bring a surface front into the area by Friday.

Meanwhile, an upper low across the southwestern USA will gradually move northeast. This low will have taken in tropical remnants and will thus have good moisture with it. A surface low pressure system will accompany the upper system.

The upper low will weaken as it moves north and east, but guidance continues to differ on its speed and what happens with it. Some guidance has the northern stream absorb the remnants of the upper low while others keep the upper low separate and farther southwest. This also affects the eventual location of the associated surface low pressure system. Thus, there is higher uncertainty in the forecast for later this week.

It now appears forcing will arrive later than previously thought, so Wednesday looks dry during the day. Otherwise, rain chances will be around Thursday into next weekend. With the uncertainty, confidence in timing and location of the highest PoPs remains low. With the weakening upper low still having tropical moisture, locally heavy rain will be a threat late week.

With the slower arrival of the system, well above normal temperatures (upper 80s not out of the question for parts of the area) will continue into Thursday. Afterward, clouds/rain/cooler air behind a front will lead to below normal temperatures next weekend.

AVIATION (18Z TAF Issuance)

Issued at 1255 PM EDT Sun Sep 27 2026

Impacts:

- Patchy fog possible overnight into Monday morning

Discussion:

Outside of patchy fog overnight/early Monday morning, VFR conditions are expected.

Some passing high clouds will be around at times through the period. Some guidance hints at broken stratus forming near KLAF late tonight, but not confident enough to include. Will have to watch though as some stratus formed this morning well northeast of the area.

Patchy ground fog will likely develop overnight at all but KIND (where the urban heat island will protect the site). Will continue to use a TEMPO for MVFR fog at all but KIND. Brief IFR conditions cannot be ruled out.

IND WATCHES/WARNINGS/ADVISORIES

None.