textproduct: Indianapolis

KEY MESSAGES

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

- Slow warm up with rain chances returning early next week

FORECAST UPDATE

Issued at 932 AM EDT Thu Apr 30 2026

No major changes needed to the forecast with conditions evolving as expected. The last of the low stratus/fog across northwestern Indiana has cleared over the last 15 minutes with clear skies across central Indiana outside of a very sparse cu field. This cu field will gradually begin to fill back in during the afternoon with mixing up to around 5kft. This should also help to mix out afternoon dew points with afternoon Min RH values in the 35 to 45 percent range.

Main focus for the afternoon forecast will be tracking the better chances for precipitation within the next shortwave within the broader cyclonic flow. Current timing looks to be during the overnight the potential for a few rumbles of thunder as models show at least some elevated instability.

DISCUSSION (Today through Wednesday)

Issued at 239 AM EDT Thu Apr 30 2026

Conditions to start the month May are expected to average below seasonal in both temperatures and precipitation. This is mostly due to deep, persistent troughing over Ontario and the Hudson Bay, suppressing the upper flow southward into the Tennessee Valley and Gulf regions. While the upper level pattern will be quasi-stagnent, there will still be some low level disturbances over the next seven days that will provide slight fluctuations in temperatures and precipitation chances. Initially, high pressure will dominate the low levels, especially across the southern Ohio Valley in the wake of yesterday's system. This will lead to calming wind early this morning with cloud cover mostly confined to the upper levels. As the surface high moves eastward, a strengthening pressure gradient and mixing heights to 1km will likely lead to gusty wind along and NE of the I-74 corridor for this afternoon.

The first of these weak low level waves is expected to arrive late night. Modest mid level ascent within this wave will likely lead to scattered light showers and mostly cloudy conditions overnight. This will buoy temperatures slightly tonight and Friday morning due to inefficient diurnal cooling, with overnight lows in the mid to low 40s' about 5 degrees warming than this morning.

Behind this wave, pressure rises within weak CAA will lead to clearing conditions once again, providing our coldest temperatures of the week. Current expectations is for efficient diurnal cooling Friday night to promote near freezing lows across far NE portions of the area, and frost concerns along and NE of the I-74 corridor. These cold temperatures will remain throughout the day with afternoon highs on Saturday only in the mid 50s.

For Sunday, the ridge axis is progged 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 (12Z TAF Issuance)

Issued at 637 AM EDT Thu Apr 30 2026

Impacts:

- Shallow fog at KLAF this morning - 15kt-20kt gusts possible this afternoon, mainly at KLAF - Light rain expected overnight with MVFR to IFR CIGs

Discussion:

Mostly clear skies this morning has led to patchy ground fog near river valleys, of which is currently impacting KLAF. Winds will increase throughout the morning and become ENE with time. Occasional gusts to 18kt are possible at KLAF/KHUF/KIND this afternoon.

Tonight, showers and low clouds will push in from the west. Showers should be light enough to keep VIS above impactful criteria, but CIGs will lower throughout the night, eventually dropping to low IFR after 05Z. By dawn, CIGs should improve to MVFR, with VFR conditions expected after 14Z.

IND WATCHES/WARNINGS/ADVISORIES

None.