textproduct: Indianapolis

KEY MESSAGES

- Near record warm temperatures today

- Showers and thunderstorms tonight into Saturday

- Severe storms are possible, mainly late this evening into early overnight across western portions of the area

- Much cooler Sunday into Monday with the potential for frost and near freezing temperatures early Monday morning

DISCUSSION (This evening through Friday)

Issued at 319 PM EDT Fri Apr 17 2026

Low pressure developing over Minnesota has brought a warm front northward through Indiana earlier today. Despite some cloud cover, temperatures have risen once again into the 80s across much of the area. Mixing has been quite efficient as well, especially further east, with dew points falling to below the NBM 10th percentile. To the west, dew points in the 50s/low 60s have been noted. These locations are deeper within the best northward moisture advection.

Warm moist advection continues into this evening ahead of a surface cold front extending southward from the low. Strong forcing along this front with large-scale lift from a deepening trough is leading to rapid convective development to our west. Mean flow roughly parallel with the initiating boundary will allow for quick upscale growth into a mesoscale convective system (MCS). This system should then progress eastward this evening.

The environment ahead of the system is characterized by deep instability to 250mb with strong easterly shear. CAPE values between 1000-2000 J/Kg are modeled to persist into the night, but with gradual stabilization occurring after about 00z. Additionally, shear magnitudes decrease with eastern extent especially from the IN/OH border eastward.

Our convective threat will be determined by how strong surface cold pools become. A stronger cold pool should allow the MCS to propagate further east faster than most models indicate. A faster MCS would then have access to greater CAPE and better shear. Cold pool shear balance would be achievable longer under such a circumstance. A slower MCS may miss the best instability and become outflow dominant early, sparing much of central Indiana from a severe weather threat.

In terms of hazards, strong damaging winds are the primary hazard. A QLCS tornado threat also exists, especially across our northwest CWA during the MCS's mature phase and where better low-level moisture is found. The best wind/tor threat is within N/S oriented line segments, and within surges which come parallel with an intensifying nocturnal low-level jet. Further south and east, the threat is reduced due to a more stable surface layer and likely a more outflow dominant system.

Best timing for severe weather is between 11pm through 4am, from west to east.

THIS WEEKEND

The aforementioned cold front arrives well behind the MCS, roughly around daybreak Saturday. High temperatures for the day occur around or before sunrise for most. Behind the front, temperatures fall from the mid 60s into the upper 40s/low 50s by the afternoon. Brisk northwesterly flow and occasional rain showers should make it feel quite miserable. Though thunder probabilities remain low, under 20 percent, enough elevated instability may be present for an isolated weak thunderstorm...mainly across our eastern CWA.

A quick rebound is likely on Sunday though not as warm as it has been recently. Highs to near 60 are expected on Sunday. A subtle shortwave diving southeast may bring about an isolated shower Sunday afternoon.

NEXT WEEK

A northwesterly flow pattern sets up next week as troughing digs in over the Great Lakes and Northeast. A stalled front Tuesday into Wednesday may bring some precipitation, but nothing too organized at this point. That front lifts back northward as a warm front allowing a warming trend to begin during the second half of the week. A return to temperatures in the 70s or even low 80s is possible again by Wednesday.

AVIATION (00Z TAF Issuance)

Issued at 740 PM EDT Fri Apr 17 2026

Impacts:

- Wind gusts up to 20-25KT continuing through most of the period - Convective SHRA/TSRA likely...mainly within 03Z-15Z - MVFR ceilings for 4-6 hours at any terminal, crossing NW to SE within 11Z-19Z - Cold fropa will veer southerly winds to mainly SW by 12Z...and WNW/NW at all terminals by 17Z

Discussion:

VFR conditions to prevail over central Indiana terminals for the majority of the period into Saturday evening...with MVFR or worse possible in convection late this evening into overnight hours... and MVFR CIGs likely, as early as 11Z-16Z at KLAF, and as late as 14Z-19Z at KBMG.

VFR skies expected to continue through at least 03Z amid mid/high cloud blowing off slowly approaching convection to the west of the region. Convective SHRA/storms to impact KLAF after 03Z, and perhaps not KIND/KHUF until closer to 06Z...with areas of IFR/LIFR possible under strongest cells. Showers and embedded storms to linger into Saturday...under a passing area of MVFR CIGs through morning to possibly midday hours. Winds will complete their shift to WNW/NW within 12Z-14Z at KLAF...down to within 14Z-17Z at KBMG.

IND WATCHES/WARNINGS/ADVISORIES

None.