textproduct: Indianapolis

KEY MESSAGES

- Scattered to numerous showers and some thunderstorms today, isolated severe storms possible

- Severe weather is likely most areas Wednesday with numerous showers and thunderstorms at times.

- Below normal temperatures will continue for much of the period

..SEVERE WEATHER LIKELY ON WEDNESDAY

Today and Tonight...

Quiet weather will continue this morning across central Indiana, with some increasing cloudiness.

Increasing southwest winds will bring some additional moisture by this afternoon. Initial forcing ahead of an upper trough will generate a scattered to broken line of convection that will move east across the area during the afternoon. Instability and shear are enough that a brief strong storm with this line can't be ruled out.

CAMs continue to show a secondary line forming closer to the surface cold front late this afternoon and then pushing east into early evening. This line will have better shear to work with and have better odds for an isolated severe storm with it, especially north. These should weaken during the evening as instability is lost.

Below normal temperatures will continue, with highs in the mid 70s to around 80 this afternoon and lows in the 50s tonight.

Wednesday and Wednesday night...

An anomalously potent storm system will impact central Indiana Wednesday.

Forcing from an upper wave and a warm front will produce a thunderstorm complex that will move east across mainly the northern half of central Indiana late morning into the afternoon. Increasing 850mb winds (around 50kt by 21Z) will pump in high precipitable water values. Shear and instability will become high enough that some severe cells are possible in the complex, especially near the surface warm front across northern portions of the forecast area. Heavy rain will also be a threat.

Most guidance is now showing a break between the initial thunderstorm complex and then additional convective development ahead of the cold front Wednesday evening into the overnight. Shear will be higher for this convection, and given the strong wind fields associated with the system, instability will recover from advection even if clouds from the earlier convection do not clear out.

All types of severe weather will be possible with the second round of convection. The tornado threat will be highest near the old warm front across northern sections of the area (or where old outflow from the earlier complex ends up), but given the shear they are possible all areas. Large hail will also be most likely north where supercells may last the longest. Given the potent wind fields, damaging winds are possible at all locations.

Also with the strong wind fields, outside of convection winds may gust to around 40 mph Wednesday into Wednesday evening. An upward trend may require a Wind Advisory.

This system nearly maxes out most parameters compared to model climatology. If the surface low deepens as expected, it could potentially set new record low pressure values for lower Michigan for the month of June.

Of course there remains some uncertainty in the details, especially with the position of the surface warm front. Some machine learning severe weather forecasts have the maximum threat farther south, closer to I-70. Will continue to monitor closely, but some severe weather looks likely regardless.

Thursday and beyond...

The cold front may linger long enough for some PoPs to be needed south on Thursday. The next best chance of rain looks to be around Sunday night when the next system moves across the area.

With the area mainly under northwest flow aloft, below normal temperatures look to continue for much of the period. Readings may return to closer to normal by early next week.

AVIATION (12Z TAF Issuance)

Issued at 606 AM EDT Tue Jun 16 2026

Impacts:

- Showers and thunderstorms around 17Z today to 02Z tonight.

- Wind gusts between 18-25kt late morning through the afternoon

Discussion:

Quiet conditions will continue through much of the morning hours. Winds will increase late morning with gusts up to around 25kt likely at times through the afternoon. Winds will then diminish.

An area of showers and thunderstorms is expected to move east across the sites in roughly the 17-21Z time frame, but then another line will move through until about 02Z. Used TEMPOs as needed for the first line and PROB30 or VC for the second. MVFR conditions are expected in convection, but lower conditions are possible if convection ends up stronger.

IND WATCHES/WARNINGS/ADVISORIES

None.