textproduct: Indianapolis

KEY MESSAGES

- Showers and thunderstorms along a line through mid-afternoon

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

- Severe weather possible on Wednesday

MESOSCALE UPDATE

Issued at 137 PM EDT Sun Jun 14 2026

Main focus currently is a line of showers and storms along the frontal boundary that continues to move eastward across central Indiana. Instability continues to be modest, but meager with 500- 1000 J/kg ahead of the line. Better shear and instability is present in Ohio with the expectation that this line remains fairly steady- state with some minor strengthening before it exits towards mid- afternoon.

Behind the front, CAA is being enhanced by an area of 25-35 mph winds with temperatures rapidly dropping into the low to mid 60s. These gusts are generally lasting around 45-90 minutes before winds drop down closer to the 15-25 mph range. Expectations are for these conditions to be similar for locations to the east as the line continues to progress further into eastern Indiana.

DISCUSSION (This evening through Sunday)

Issued at 137 PM EDT Sun Jun 14 2026

Overview.

Central Indiana can look forward to a brief but welcome break from the recent active and humid weather for the early portions of the work-week. Dry weather is expected for Monday in the aftermath of showers and storms that will impact the area through the evening. Temperatures will peak only in the low to mid-70s but by Tuesday humidity levels will begin to creep back up alongside chances for scattered showers and thunderstorms. On Wednesday, a stronger storm system is expected to track into the Midwest, bringing the potential for multiple rounds of heavy rainfall, localized flash flooding, and strong to severe thunderstorms. Drier conditions and more seasonable temperatures are anticipated to return for the upcoming weekend.

Tonight through Tuesday.

The primary synoptic driver through the short-term period will be the structural evolution of an upper-level cut-off low spinning over northern Ontario. This feature will keep central Indiana situated on the southern fringe of a broad, longwave trough characterized by lowered heights across the north-central US. Tonight will see robust post-frontal CAA behind the departing surface boundary, causing low- level wind profiles to shift to the northwest. Rapid deep-layer dry air entrainment will effectively scour out the residual high-theta-e airmass, dropping PWAT values significantly. Strong radiational cooling under clearing skies and a decoupling boundary layer will allow overnight minimums to drop efficiently into the low to mid-50s by Monday morning.

A weak surface high pressure center will then build southward from the Northern Plains into the Ohio Valley Monday. Continued CAA will keep temperatures mild with highs only in the low to mid 70s A minor, moisture-starved shortwave embedded in the northwest flow aloft will cross the Great Lakes on Monday afternoon with both GEFS and EPS ensemble means show dry columns which will keep impacts limited to a more robust afternoon cu field.

By Tuesday, the synoptic pattern shifts as the surface anticyclone slides east toward the mid-Atlantic, causing low-level wind vectors to veer toward the south-southwest. This will bring a return to a WAA regime with moisture advection ahead of a secondary shortwave dropping out of south-central Canada. Boundary layer recovery on Tuesday will initially be modest, with surface dewpoints rising slowly into the upper 50s. However, stronger mid-level forcing and an amplifying low-level theta-e gradient will act to erode the capping inversion by late Tuesday afternoon.

Considerable variance exists within deterministic and ensemble guidance regarding the exact timing and placement of the Tuesday system The deterministic GFS remains a drier and more progressive outlier, suggesting that the primary mid-level forcing stays displaced too far to the north to break the low-level cap, which would keep central Indiana dry through Tuesday afternoon. Conversely, the ECMWF and several regional CAMs are much more aggressive, bringing a deeper wave that initiates a line of scattered showers and embedded thunderstorms across the area by Tuesday evening. While the overall severe threat remains marginal on Tuesday due to limited surface-based instability, modest mid-level lapse rates around 6.5C/km and 0-6 km bulk shear around 35 knots could support isolated downbursts or small hail. This initial wave will ultimately prime the environment for a much more volatile, high- PWAT severe weather and flash flooding threat later on Wednesday and Thursday as deep Pacific energy interacts with a building warm front near the area.

Wednesday through Sunday.

An active weather period will be in store during this period as the upper flow will start on Wednesday through Friday being dominated by broad cyclonic flow over Canada, resulting a quick upper flow across the northern United States. This will result in several waves passing across our region within the flow aloft, providing shower and storm chances. Of note, a stronger wave, along with a well organized surface low is suggested to push across the Great Lakes on Wednesday Night into Thursday. This system is hinting to be potent. Indiana will be in the warm sector that night as the upper forcing passes. A strong LLJ of 60-70 knts is expected to push across Indiana within that flow. Forecast soundings at that time suggest favorable conditions for convection. Thus we will be watching the evolution of this storm system over the next few days as potential for severe weather will be very good, especially on Wednesday Night.

More rain chances will persist on Thursday as broad cyclonic flow remains in place aloft and another weak wave amid this flow will pass. Indiana looks to be still impacted by the wrap around flow of the departing surface low, thus chances for wrap around showers and storms will need to be included.

For the moment, dry weather looks in store for Friday as high pressure builds across the area while weak ridging and a break within the upper flow is expected to be in place within the upper flow.

Chances for rain will return on Saturday and Sunday as a pair of low pressure systems emerge from the plains, one arriving from the southwest on Saturday and a second system arriving on Sunday from the plains as the quick upper flow begins to buckle as an upper disturbance passes.

Temperature wise through the period, there are no intrusions of hot tropical air, and the Canadian low to the north remains the main player. Thus temperatures will be below normal through the week ahead.

AVIATION (18Z TAF Issuance)

Issued at 1147 AM EDT Sun Jun 14 2026

Impacts:

- Brief MVFR conditions early this afternoon. - VFR returns late this afternoon. - Winds becoming NW and gusty this afternoon.

Discussion:

A cold front pushing across Central Indiana will be near IND and BMG near 18Z. A few showers, as seen on radar, will quickly be exiting to the east near issuance. Thus these showers and the associated MVFR cigs are expected to quickly exit, bringing a return to VFR at all TAF sites by 19Z-20Z.

Models suggest good subsidence arriving in the wake of the front along with a moderate pressure gradient. This will lead to clearing skies this evening and a loss of cigs.

A ridge of surface high pressure will arrive across the area on Monday. This will keep VFR conditions ongoing.

IND WATCHES/WARNINGS/ADVISORIES

None.