textproduct: Indianapolis

KEY MESSAGES

- Near record highs today with readings in the 80s (except across our northern counties).

- Showers and thunderstorms expected this evening, strong to severe storms possible with large hail and damaging winds being the primary hazards.

- Cooler on Monday with a warming trend through the workweek.

- Showers and thunderstorms possible late Thursday.

SHORT TERM (Today and tonight)

Issued at 255 AM EDT Sun Mar 22 2026

Southerly flow continues ahead of a strong cold front approaching from the north. Temperatures as of 06z are still in the low 60s across central Indiana despite clear skies and winds under 10kt. The air mass in place is very warm, originating from anomalously strong ridging just to our west. Temperatures within the 925-850mb layer are between 18-24 degrees C. A shallow inversion is noted on IND ACARS soundings, and it is expected that this will easily mix out once the sun rises. Assuming efficient adiabatic mixing, surface temperatures may sore through the 70s and into the low 80s by the afternoon. Higher resolution guidance that has done well with the warm temperatures lately even suggests mid to upper 80s from I-70 southward. Temperatures further north are a bit trickier since the cold front may arrive before diurnal mixing kicks off. Once the front sweeps through, a quick drop in temperatures through the 60s and into the 50s is expected.

SEVERE WEATHER POTENTIAL

Another aspect of today's cold front is the potential for showers and thunderstorms. In addition to the very warm air, moisture advection is also ongoing and dew points are expected to rise into the 50s and low 60s. Height falls aloft point towards steepening lapse rates and broad synoptic-scale lifting. Guidance is in fairly good agreement showing between 1500-2000 J/kg MUCAPE developing this evening with equilibrium levels around 10-12km. Model shear profiles depict long and curved hodographs corresponding to roughly 60-70kt of shear. More than enough shear and instability are present for strong to severe thunderstorms later today.

Shear magnitude suggests supercells are possible while shear vectors roughly parallel to the cold front suggest a linear mode. As such, some supercell thunderstorms may develop initially before growing upscale into a line. Additionally, the front is very strong and moving quickly south, and likely undercuts developing updrafts. This may cause most if not all of the storms later today to be elevated. Model soundings suggest that updrafts will be rooted around the 850- 800mb layer. Since the storms won't "feel" the shear below 850mb, we can effectively ignore that part of the hodograph. Taking this into account, our effective hodograph is long and straight. Combined with the high EL, this implies that large to very large hail is possible with the initial elevated supercells. However, once upscale growth occurs a transition to primarily damaging winds is likely. Tornado potential is very low, due to the strong cold air undercutting the storms.

Timing looks to be mainly in the late afternoon and evening, roughly from 23z to about 04z. Thunderstorms are possible well after the front moves through, since they are elevated, and rapidly cooling surface temperatures will not mitigate the hail and wind potential.

MONDAY

Rapid cooling behind the front/storms continues through Monday morning. Lows may be near freezing, which would be a nearly 50 degree drop in temperature behind the front. Highs on Monday may rebound to near 50 degrees under partly cloudy skies.

LONG TERM (Monday through Saturday)

Issued at 255 AM EDT Sun Mar 22 2026

Anomalous ridging over the western US is modeled to continue through much of the coming week. Combined with low amplitude troughing over the northeastern US, the overall flow pattern over Indiana looks to be northwesterly. This pattern has been in place for a few days now, and has featured warmer-than-average conditions occasionally interrupted by fast-moving cold fronts. The cold front expected to arrive later today will bring temperatures back to near normal to begin the period.

With a progressive jet pattern overhead, the cool down is not expected to persist that long and a gradual warming trend begins on Tuesday. High temperatures rebound into the mid 60s / low 70s by Wednesday, and then into the mid/upper 70s on Thursday.

The next strong cold front, quite similar to the one we'll see today, arrives late Thursday evening. In fact, the set up is nearly identical to this afternoon. As such, the threat for strong to severe thunderstorms exists. Some minor details remain in question though, especially timing and how effectively the front undercuts developing convection if at all.

A second dramatic cool-down is then shown by Friday with high temperatures as much as 40 degrees cooler than the previous day.

AVIATION (06Z TAF Issuance)

Issued at 142 AM EDT Sun Mar 22 2026

Impacts:

- Wind gusts tomorrow afternoon to evening of up to 25-35 kt - Abrupt wind shift to northerly mid to late afternoon with cold front - Showers and thunderstorms are possible this evening, with poor flying conditions.

Discussion:

A strong cold front is approaching Indiana from the north, and will arrive during the afternoon hours with an abrupt wind shift to northerly. Winds may gust to 25-35kt both ahead of and behind the front.

Showers and a few thunderstorms appear increasingly likely with the front, and a prob30 group has been included for each terminal. Strong to severe thunderstorms are possible as well, with large hail and strong winds. IFR or worse conditions are possible within showers and storms.

Showers and storms come to an end around 04z with winds diminishing thereafter as well. MVFR ceilings may linger into the morning hours on Monday.

IND WATCHES/WARNINGS/ADVISORIES

None.