textproduct: Indianapolis

KEY MESSAGES

- Hot and humid conditions expected again today, isolated showers and storms possible this evening

- Peak heat indices around 100 degrees each afternoon through Saturday

- Greater chance for showers and storms Friday through the first half of the weekend, primarily during the afternoon and evening

FORECAST UPDATE

Issued at 954 AM EDT Thu Jul 16 2026

Quiet weather conditions are ongoing across central Indiana as surface high pressure remains the dominant weather feature. Aloft, upper ridging is being suppressed and gradually pushed further south due to subtle waves moving through the northern Great Lakes. Isolated to widely scattered diurnal showers and a few storms are possible this afternoon into the evening, primarily across southwest portions of the area where deeper moisture is in place. Further northeast, weakening large scale ascent may allow for isolated diurnal showers or a stray storm to develop, but less impressive moisture leads to lower confidence.

Patchy canadian wildfire smoke has made its way into far northeast portions of Delaware and Randolph county this morning. Light surface flow becoming more northerly later today could allow for the smoke to gradually shift further south into more north/northeastern counties across central Indiana.

DISCUSSION (Today through Wednesday)

Issued at 302 AM EDT Thu Jul 16 2026

Upper ridging and surface high pressure will continue to promote mostly quiet weather for much of the day. The stagnant suppressed airmass will also keep hot-humid conditions in place with poor air quality across portions of central Indiana. A Heat Advisory remains in effect for north/northeast portions of central Indiana, including the Indianapolis metro, from noon through 8PM EDT today.

Isolated convection appears possible this evening, mainly in the far SW and far N, as the upper ridge starts to gradually breaks down. Latest CAMs generally depict convection developing after 4PM due to the weakening large scale subsidence above the stagnant hot-humid airmass.

A more active pattern is expected starting tomorrow with multiple disturbances moving through the region. The first disturbance will move in on Friday supporting higher rain chances. Modest ascent from the mid-upper level feature combined with daytime heating of a hot- humid airmass will promote numerous showers and thunderstorms by the afternoon hours. Additional scattered convection can be expected late Saturday as another shortwave and associated cold front push through.

Moderate to strong destabilization ahead of the approaching cold front late Saturday, along with modest enhancement of mid-upper level flow, could support a few stronger thunderstorms, primarily across northern portions of central Indiana. Forecast soundings depict up to 25 kt of effective shear, strong destabilization with steep low-level lapse rates, and DCAPE values as high as 1200 to 1400 J/KG. These parameters suggest the potential for loosely- organized storms capable of producing isolated damaging wind gusts. Isolated hail cannot be ruled out, but relatively weak deep-layer shear should limit the threat. Efficient rainfall rates from warm rain processes could also result in localized flooding during the period.

Going into Sunday and next week, long range guidance generally depicts upper ridging and weak surface high pressure building in Sunday. This will provide mostly quiet weather conditions until another shortwave approaches late Monday into Tuesday morning. Exact details remain uncertain due to diverging model solutions. It is worth noting guidance suggest more significant cold air advection with this disturbance which favors a cooler and drier pattern towards the middle of next week.

AVIATION (12Z TAF Issuance)

Issued at 655 AM EDT Thu Jul 16 2026

Impacts:

- Brief patchy fog possible at LAF the first hour of the period

Discussion:

VFR conditions are expected through the period with light winds.

Skies will mainly have elevated smoke and some high clouds. Scattered cumulus will pop up again this afternoon.

Isolated showers and thunderstorms may develop Thursday afternoon, especially near the southern sites. At the moment coverage is expected to be too low to mention.

IND WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 8 PM EDT this evening for INZ021-029>031- 036>042-045>049.