textproduct: Indianapolis

KEY MESSAGES

- Record warmth today with highs reaching the upper 80s to low 90s

- Multiple rounds of rain and scattered thunderstorms Tuesday night through Thursday night

- Sharply colder Friday with northwest wind gusts of 30 to 40 mph

- Frost and localized freeze potential late Saturday night into early Sunday morning

DISCUSSION (Today through Monday)

Issued at 130 AM EDT Tue Oct 13 2026

Today Through Wednesday.

Broad mid-level ridging centered over the Southeast expands across the Ohio Valley today while a deep trough digs across south-central Canada and the Upper Midwest. South-southwesterly boundary layer flow downstream of an approaching surface cold front will reinforce warm thermal advection across central Indiana. Forecast soundings indicate 850mb temperatures climbing to 16-17C with deep diurnal mixing up to 800mb. The combination of WAA and plenty of sun will allow for temperatures to rise into the upper 80s to potentially low 90s, breaking records. Momentum transfer within the mixed layer will support sustained southwesterly surface winds of 15 to 20 mph with gusts peaking between 25 and 30 mph.

The synoptic surface cold front will decelerate Tuesday night as upper-level flow orients quasi-parallel to the boundary. Mesoscale guidance, including the HRRR and HREF members, focuses initial pre- frontal convective development across northwestern counties after midnight as a 35 kt low-level jet intercepts the frontal zone. Instability remains largely elevated and diurnally capped, with MUCAPE values generally under 500 J/kg, limiting severe convective potential to isolated general thunder outside of a low-end threat for gusty winds.

The frontal zone sags into central Indiana Wednesday, serving as a focus for precipitation as mid-level frontogenesis tightens. High-resolution guidance shows precipitable water values surging to 1.4 to 1.6 inches along the boundary, exceeding the 90th climatological percentile for mid-October. Right-entrance region upper jet dynamics and continuous moisture transport will support widespread rain and embedded convective clusters throughout Wednesday afternoon and Wednesday night. Afternoon highs Wednesday will exhibit a marked thermal gradient, ranging from the low to mid- 60s in the northwest behind the front to upper 70s and lower 80s across south-central Indiana.

Thursday Through Monday.

A secondary shortwave rotates through the base of the deepening eastern longwave trough Thursday, inducing a weak wave of low pressure along the stalled baroclinic zone over the Ohio Valley. Strong multi-level deformation and mid-level FGEN combined with deep moisture will maintain high PoPs through Thursday evening before the boundary finally clears the forecast area to the southeast. Multi- model ensemble consensus aligns with WPC guidance depicting widespread event-total QPF between 1.00 and 2.00 inches across central Indiana, providing much-needed drought relief.

Cold air advection strengthens drastically Thursday night into Friday behind the frontal passage as an amplified 500mb polar trough settles over the Great Lakes and eastern CONUS. An intense surface pressure gradient between the departing low and a 1028mb Canadian surface high will combine with steep low-level lapse rates to promote deep boundary layer mixing on Friday. Sounding profiles show 35 to 40 kt winds at the top of the mixed layer, which will easily translate to surface gusts of 35 to 40 mph throughout Friday afternoon. Highs on Friday will be held in the mid-50s to near 60F despite clearing skies as a result of the strong CAA.

The core of the thermal trough crosses the region Friday night into Saturday, with 850mb temperatures dropping to between -2C and 0C. Highs Saturday will struggle to reach the low to mid-50s under cold northwest flow. The primary frost/freeze window remains Saturday night into early Sunday morning. The Canadian surface anticyclone settles directly over the Ohio Valley by 09Z Sunday, resulting in clear skies and a decoupled wind field. Radiational cooling within this dry continental airmass will cause surface temperatures to drop into the low to mid-30s across central Indiana. Widespread frost appears likely across rural and sheltered areas, with a localized freeze probable in typically colder drainage basins.

The surface ridge axis shifts toward the Mid-Atlantic on Sunday and Monday, allowing low-level flow to veer to the south-southwest. Height rises aloft downstream of a Western trough will promote thermal moderation, returning highs to the lower 60s Sunday and upper 60s by Monday under dry conditions.

AVIATION (12Z TAF Issuance)

Issued at 547 AM EDT Tue Oct 13 2026

Impacts: - Southwesterly winds to gust up to 20kt 16Z to 23Z

Discussion:

VFR conditions expected through the TAF period with only passing cirrus through the day today. Southwesterly winds will gradually ramp up in speed through the morning hours with gust up to 20kt at times through the afternoon and early evening. Those winds will then drop back to near calm tonight with high clouds gradually increasing in coverage through the night ahead of rainfall tomorrow morning.

IND WATCHES/WARNINGS/ADVISORIES

None.