textproduct: Indianapolis

KEY MESSAGES

- Showers and thunderstorms likely today.

- Much cooler temperatures through Tuesday night with highs in the low-mid 70s and lows in the 50s

- Wednesday-Thursday: overall seasonable warmth/humidity...with potential for multiple rounds of unsettled weather

- Severe weather possible on Wednesday

DISCUSSION (Today through Saturday)

Issued at 314 AM EDT Sun Jun 14 2026

Widely scattered showers and a few thunderstorms have been observed across central Indiana since Midnight but coverage is very low. Will maintain slight chance PoPs in areas that showers are occurring, trimming PoPs elsewhere, before allowing precip chances to increase towards dawn.

A potent short wave trough embedded in a larger long wave trough will swing through this afternoon. At the surface, a cold front is advancing from the northwest. Though low-level flow is weak, moisture advection continues ahead of the approaching boundary. Filtered sunshine this afternoon should lead to modest boundary layer destabilization, resulting in between 500 to 1500 J/Kg MLCAPE.

Showers and thunderstorms are likely this afternoon, initiated by the front and aided by synoptic forcing. Thunderstorm intensity may be mitigated by poor mid to upper-level lapse rates. Though storms may be scattered to numerous, the relatively weak updrafts will limit severe weather potential. A few severe storms cannot be ruled out, however, since around 40kt of bulk shear may allow for some storm-scale organization. Damaging winds would be the primary hazard, given a quasilinear storm mode forced by the front.

Northwesterly flow intensifies later this afternoon after the front sweeps through. Winds may gust to 20-25kt at times before surface high pressure arrives overnight. Wind speeds decrease quickly, becoming calm to light and variable. Patchy fog may be possible at times across the region tonight, especially in rural areas.

Broad troughing remains over the northern CONUS this week with multiple waves embedded within the quasi-zonal jet stream that rounds its base. These waves may bring periodic cloudiness and even rain chances at times Monday and Tuesday. By Wednesday, a more potent wave arrives with the potential for thunderstorms and severe weather. Broad troughing persists through the week and into the weekend. Temperatures this week are expected to remain near to below normal due to the persistent troughing.

WEDNESDAY SEVERE POTENTIAL

Digging a bit deeper into the system poised to bring active weather back to the region, we see fairly good agreement within deterministic guidance. Global models show a very low amplitude shortwave rounding the base of the broader trough on Wednesday. This enables cyclogenesis over the upper Midwest, with the resulting surface low tracking east into the Great Lakes. A potent low-level jet then develops in response to the deepening low, allowing for strong warm air and moisture advection northward. Additionally, the upper-level jet stream remains overhead. Model hodographs are long and curved, with a southeasterly mean shear vector.

A few scenarios exist regarding convective evolution. First, the strong warm moist advection may be sufficient to initiate convection Tuesday night far upstream over Iowa. This could consolidate into an MCS and propagate southeastward into the strong low-level jet and warm moist advection, aided by southeasterly shear. Damaging winds and localized flooding would be the primary hazards in such a scenario.

Second, there is no early convection and or the atmosphere recovers from earlier storms (strong low-level jet may easily allow this to happen even if there is morning convection, simply by advecting the rain cooled air mass northward). Atmospheric instability is maximized by continued strong warm moist advection and solar insolation. Thunderstorms initiate along the surface cold front over Illinois and propagate southeastward. Shear vectors perpendicular to the advancing front may allow for discrete mode initially, with potential for supercells. All hazards are possible in this circumstance. Eventually, convection would grow upscale becoming primarily a wind threat.

There are a lot of moving parts with this, and predictability is currently low to medium. Guidance still needs to properly resolve the initiating wave and surface low. Additionally, the potential for early convection is always a wild card and can substantially alter the pre-storm environment. Given the potential for a strong low, potent low-level jet and shear, it is certainly worth watching over the coming days.

AVIATION (12Z TAF Issuance)

Issued at 649 AM EDT Sun Jun 14 2026

Impacts:

- Chance for -SHRA between 14-19Z today, thunderstorms possible - MVFR ceilings with IFR possible this morning - Wind shift to northwesterly within 14Z-18Z - Wind gusts 20 to 25 kt this afternoon

Discussion:

A cold front is approaching from the northwest and will bring showers at times and possibly a thunderstorm. Showers/storms will be scattered so VCSH will be carried as a prevailing and a Prob30 is added for potential impacts.

MVFR ceilings are expected to develop this morning as boundary layer moisture increases. MVFR conditions could persist through the morning hours. IFR conditions are possible this morning, from 12z to 14z. Some fog is also possible at times with brief visibility reductions.

The cold front itself passes through during the course of the afternoon, causing winds to become northwesterly. Gust to between 20- 25 knots are possible at times.

Winds diminish quickly tonight as surface high pressure builds in. Patchy fog is possible, especially if winds become calm or light and variable.

IND WATCHES/WARNINGS/ADVISORIES

None.