textproduct: Indianapolis

KEY MESSAGES

- Quiet and pleasant weather tonight

- Severe thunderstorms possible Monday afternoon into Monday night.

- Isolated Showers and thunderstorms possible on Tuesday, mainly across southern Indiana.

- Cooler temperatures expected Wednesday through Sunday.

DISCUSSION (This evening through Sunday)

Issued at 203 PM EDT Sun Apr 26 2026

Surface analysis this afternoon shows high pressure in place over Ontario and Quebec, spilling southwest across the Great Lakes to Indiana. This was resulting in a cool, easterly flow. GOES19 shows earlier stratus clouds had burned off, leading to mostly sunny skies across central Indiana. Aloft, water vapor shows ridging in place over Indiana and the Great Lakes extending into eastern Ontario. Strong subsidence was shown over Indiana. Temperatures across the the forecast area were rising through the 60s.

Quiet weather is expected this evening. The strong high pressure and ridging in place aloft will continue to result in a dry column this evening and into the early overnight hours. Given our dew points in the lower 50s, lows mainly in the mid 50s will be expected. Meanwhile, convection over the plains states overnight will begin to propagate toward Indiana. Convective debris blow-off should begin arrive late tonight allowing for some increasing high clouds.

AN ACTIVE WEATHER DAY IS EXPECTED ON MONDAY WITH BEST SEVERE WEATHER POTENTIAL ON MONDAY NIGHT

As we begin Monday, there is uncertainty in regard to progression of upstream convection that will have developed overnight. Models disagree on how far and how long the remnants of that system will linger across Indiana. If the remnants fail to reach Indiana, or only produce high cloud that dissipates, the severe weather threat for Monday night will be remain significant as favorable conditions for heating and destabilization will be in place. Should the remnants linger and prevent heating through the day, the severe threat will be somewhat diminished. All of this is occurring because the surface high will drift well east of Indiana tonight, allowing the return of warm and more moist southerly flow and placing central Indiana within the warm sector. Meanwhile aloft, a moderate short wave pushing out of the plains will push toward Indiana, with diffluent flow aloft, which will push to Indiana on Monday night. Other ingredients in play include a moderate LLJ of 50-60 knots ahead of the associated surface low pushing across Indiana and the 305K GFS isentropic surface shows strong mid level lift pushing into Indiana during the afternoon and evening with high specific humidity. Forecast soundings suggest favorable CAPE with values over 2K J/KG. Model CAMS are suggesting on convective developing over Illinois in the afternoon, possibly supercellular, before pushing eastward and transitioning to a strong QLCS pushing across Indiana. Models differ on intensity of the line, but all seem to focus on a rough time frame of 00Z-04Z. As these storms transition to QLCS, the main weather hazard will be damaging straight line winds. Although not the main threat, isolated, brief spin-up tornadoes will also be possible. These storms should exit Indiana during the overnight hours, ending the severe weather threat.

Thus summing up Monday, small chances for morning/lunchtime precip due to leftover thunderstorms upstream, best chances for this are in NW central Indiana. This will be followed by a mostly sunny and warm afternoon with highs reaching the upper 70s to around 80, with strong storms expected on Monday night.

For the moment, Tuesday looks dry as southwest flow will be in place as an upper low sets up over Canada. Little in the way of upper support looks to pass and forecast soundings suggest subsidence and a dry column in the wake of the Monday night wave and cold front. Look for highs on Tuesday to only reach around 70s.

Wednesday through Sunday...

Continued cooler weather is expected from mid week through the weekend. This will be primarily due to a strong and broad area of upper level low pressure over northern Ontario. This large low will provide cool cyclonic flow across the NE quarter of the United States, including Indiana. A steady stream of cool, Canadian air will flow across Indiana during this time. Several short waves within the cyclonic flow aloft look to pass from time to time. This in combination with diurnal heating will bring chances for showers most days. At the moment, a lack of a wave on Thursday along with a dry column shown within forecast soundings suggest lesser chances on that day, however confidence in that remains low due to possible timing differences and changes that could occur in upcoming runs. Within the lower levels, models suggest surface low passing near Indiana on Wednesday and Friday, thus for the moment those appear to the best days for showers and storms for the moment.

Compared to yesterday, models suggest pushing the upper low east on Sunday now, as they did this on Saturday yesterday. Stronger high pressure is shown to settle over Indiana and the Ohio Valley as yet another cold front appear to approach from the northwest for Sunday night.

AVIATION (18Z TAF Issuance)

Issued at 118 PM EDT Sun Apr 26 2026

Impacts:

- S-SE wind gusts up to 25 kt Monday

Discussion:

Broad area of surface high pressure centered over the eastern Great Lakes region will keep easterly winds from 8-10 kts across the terminals through early tomorrow morning. Earlier MVFR ceilings have cleared, and expect just some patchy cumulus and cirrus clouds this afternoon.

As a stronger area of low pressure develops over the upper MS valley, winds will increase from the S-SE with gusts from 22-24 kt at all terminals by late Monday morning with stronger wind gusts during the afternoon.

Models are in disagreement with the amount of precip possible during the 18-00Z period owing to only weak instability developing during this time frame and fairly dry low levels initially. Have opted to play it fairly conservative with VCSH and Prob30 for KIND during the later afternoon/evening (20-00Z) period. At the very least increasing mid level clouds are expected with mostly cloudy skies by 18Z Monday at all the terminals.

IND WATCHES/WARNINGS/ADVISORIES

None.