textproduct: Indianapolis

KEY MESSAGES

- A round of strong to severe storms are expected this evening into tonight, all hazards are possible

- Cooler on Friday, with a warming trend resuming over the weekend

- Active pattern may develop first week of April

FORECAST UPDATE

Issued at 933 PM EDT Thu Mar 26 2026

Overall forecast remains in good shape with only minor adjustments necessary. For the latest details on the severe convective threat in the near term, see the latest MESOSCALE UPDATE section below.

Thunderstorm activity will continue to move through the area overnight as the boundary pushes southward. Severe threat will eventually transition more to minor hydrologic concerns as pockets of moderate to locally heavy rainfall train over previously impacted areas. MRMS precipitation estimates are generally an inch or less aside from a small area that may be at least slightly hail contaminated, and flash flood guidance values are relatively high for the most part, so again, anticipate primarily minor hydrologic concerns if any.

Precip will remain elevated/largely post-frontal so going PoPs were generally in good shape.

MESOSCALE UPDATE

Issued at 905 PM EDT Thu Mar 26 2026

Recent special sounding out of IU/Bloomington shows substantial amount of inhibition from a capping inversion located around 800 mb/6kft AGL (cinh around 250 j/kg). Early evening thunderstorm activity that was located along and just north of the frontal boundary has diminished as the boundary has pushed into an increasingly stable surface based parcel environment. RAP mesoanalysis showing cinh around 100 j/kg around I-70 corridor where the boundary is presently located as of 0030Z. Surface analysis shows between 4-6 mb/2 hr pressure rises located over central IL into Northern IN. This will support an accelerated southward push of the frontal boundary through midnight.

Despite the weakening trend in convection the last few hours, sufficiently strong deep layer shear combined with elevated instability (around 1000 j/kg of MUCAPE) and steep mid level lapse rates still support an environment for marginally severe hail. Recent uptick in convection to the west in northern IL appears to be associated with increasing upper level divergence. This activity is rooted around 2-3km AGL, on the frontal inversion per VWP from ILX and LOT radars. Around 40-50 kts of deep layer shear remains evident between 2-3km and 6 km, which will continue to support marginal supercell structures. Given fairly fast storm motions, this activity will be moving into areas mainly north of I-70 through 03Z. In addition, activity will tend to train over similar areas and the threat for minor flooding will gradually increase especially after midnight EDT.

SHORT TERM (This evening through Friday)

Issued at 143 PM EDT Thu Mar 26 2026

Some weak upper energy may continue to produce isolated showers or storms north of central Indiana into mid-afternoon, with no severe threat from these. Record warm temperatures and breezy conditions will persist this afternoon ahead of a potent cold front.

Warm air aloft will continue to act as a cap for the remainder of the afternoon across central Indiana. However, forcing and good convergence with the potent cold front will create thunderstorms along it north of the area, with storms potentially reaching far northern portions of central Indiana after 600 PM EDT.

Strong shear and instability of 1000-1500 J/kg of CAPE will lead to the potential of severe convection, especially across the northern forecast area where CAPE is highest. If supercells form and remain ahead of the front, a few tornadoes will be possible in addition to large hail and damaging winds. Initial storms will then form a line along the front which will move south through the evening and could reach Indy by 9-10PM. As the storms become linear, the threat for wind damage will increase with tornado threat lowering some. (Tornado threat will remain non-zero along a QLCS).

Additional showers and storms will develop behind the surface front and remain elevated. Large hail with be a threat with these, though wind damage remains possible.

Instability will weaken later this evening into the overnight, diminishing the severe threat.

Another concern is localized flooding with potential training of storms across the northern forecast area tonight. HREF LPMM shows the potential of over 2 inches of rain north of I-70. Will continue to mention the threat of heavy rain and flooding in messaging tonight.

Temperatures will drop sharply behind the front, with the HRRR showing the potential of a 25-30 degree drop in an hour at Lafayette as the front passes. Lows tonight will be in the mid 30s north to mid 40s south.

Some rain will linger in the south Friday morning as the system exits. Otherwise, much colder and drier air will continue to filter in. Highs will only reach the middle 40s north to the middle 50s south.

LONG TERM (Friday night through Thursday)

Issued at 143 PM EDT Thu Mar 26 2026

Central Indiana will be in northwest flow aloft through the weekend. High pressure will keep the weather quiet. Temperatures will remain below normal with highs around 50 on Saturday, but warm advection on the west side of the high on Sunday will bring a return to above normal readings in the 60s.

Next week, an upper high will slide across the far southern USA. The edge of the upper high will nudge into the local area, bringing highs in the 70s for most areas Monday through Wednesday.

A surface front will set up north of central Indiana for Monday through Wednesday. Most forcing from the front will remain out of the area, but upper impulses moving around the high may be enough to bring chances for some showers and thunderstorms at times.

Late in the period, an upper wave moving through may bring the surface front south into the area on Thursday. This would bring better chances for rain to the area, as well as at least slightly cooler temperatures. Uncertainty remains high on the details though that far out.

Looking into next weekend, upper troughing to the west and the high to the east will put central Indiana in potentially active southwest flow, with energy ejecting from the trough at times.

AVIATION (18Z TAF Issuance)

Issued at 107 PM EDT Thu Mar 26 2026

Impacts:

- Wind gusts near 30kt possible this afternoon

- Convection moving north to south 23Z-06Z. Severe convection possible, especially KLAF/KIND

- Wind shift to N through the evening

- MVFR ceilings overnight through Friday morning

Discussion:

A cold front will move south through the sites roughly 23Z-06Z, shifting winds to the north. Convection will be along and behind the front, with rain lingering behind the convection overnight. Severe convection is possible with damaging winds and very large hail, mainly before 05Z. IFR and worse possible in convection.

Ceilings will lower to MVFR behind the front and will persist through Friday morning. Brief IFR is possible.

IND WATCHES/WARNINGS/ADVISORIES

None.