textproduct: Indianapolis

KEY MESSAGES

- Isolated showers ending northeast

- Below normal temps to continue through the weekend with frost possible Saturday and Sunday

- Slow warm up with rain chances returning early next week

DISCUSSION (This evening through Wednesday)

Issued at 137 PM EDT Wed Apr 29 2026

Overview.

Generally quiet weather is expected for much of the 7 days with the synoptic pattern being dominated by cyclonic flow aloft associated with a deep low across the Great Lakes. The first round of rain will be this afternoon and evening with weak instability due to cold air aloft. Additional chances for rain arrive Thursday night into Friday as another weak shortwave moves through the broader flow. Cyclonic flow will then become weaker towards the weekend with a cold air mass bringing marginally favorable conditions for frost Saturday and Sunday mornings. Additional rain chances return early next week as another low moves in from the northwest.

Rest of Today through Friday.

The primary forecast challenge through the next 24 hours revolves around the potential for showers and possibly a rumble of thunder across central Indiana in the aftermath of the exiting system that brought active weather to the state over the last few days. Mid- level water vapor imagery reveals a compact shortwave trough pivoting across the broader cyclonic flow across Great Lakes, providing modest ascent and allowing for at least isolated showers through the early evening. With the CAA aloft, temperatures will continue to cool even as the surface slowly warms which will allow for a skinny CAPE profile up to around 12-15kft. This low LFC will help to limit the thunder potential with the LFC expected to remain at or warmer than -10C, but the strongest cells of the day could produce a few rumbles of thunder or graupel.

As we transition into Thursday, cyclonic flow will continue with another shortwave bringing additional showers during the late overnight into Friday. Recent model runs have trended to towards a slightly more robust shortwave even as timing differences continue, so will plan on bringing POPs up slightly during the overnight hours and early Friday. Moisture return will be somewhat limited by the preceding dry air mass, so any precipitation should remain light and primarily shower-based rather than widespread heavy rain.

Saturday Through Wednesday.

Attention then shifts to the potential for frost as we head into the weekend. A reinforcing shot of cold air behind the Friday front will drop temperatures well below seasonal norms, with highs struggling to reach the 60 degree mark. On Saturday morning, the surface high pressure ridge axis remains slightly to the northwest, which may keep enough of a breeze and cloud cover in place to limit widespread frost with patchy to areas of frost more likely. However, by Sunday morning, the ridge axis is forecast to settle directly over or just south of central Indiana. Radiational cooling looks more favorable Saturday night into Sunday but with the surface flow becoming more southerly, there remains some question as to how cool temperatures fall and whether it will be cold enough for frost.

Looking ahead to next week, a gradual pattern shift is anticipated as the persistent eastern trough begins to deamplify. A modest warmup is expected to bring temperatures back toward late-spring normals by Monday and Tuesday. While latest ensemble guidance suggests low probabilities for precipitation early in the week due to weak shortwaves in the west-northwest flow, confidence in significant rainfall is low. Recent frontal intrusions into the Gulf have suppressed deeper moisture, which will likely keep any early- week activity disorganized and moisture-starved.

AVIATION (00Z TAF Issuance)

Issued at 654 PM EDT Wed Apr 29 2026

Impacts:

- Brief wind gusts to 20kt early. 1t-20kt gusts possible Thursday.

Discussion:

VFR conditions are expected through the period. Cumulus/stratocumulus will gradually diminish this evening, with high clouds also moving through. Late in the period, clouds will increase from the west as another system approaches.

High pressure will diminish winds tonight, but winds will increase again Thursday ahead of the next system.

IND WATCHES/WARNINGS/ADVISORIES

None.