textproduct: Indianapolis

KEY MESSAGES

- Isolated showers this evening into early Sunday; a few rumbles of thunder northeast of Indianapolis this evening

- Additional threat for rain and storms late Tuesday and Tuesday night

- Seasonably cool through midweek with much warmer air arriving by next weekend

DISCUSSION (This Evening through Saturday)

Issued at 143 PM EDT Sat May 9 2026

A strong upper level low south of James Bay will maintain a general longwave trough across much of the eastern half of the country into early next week. Ridging aloft will briefly replace the departing trough prior to another upper low diving into the eastern Great Lakes by the middle of next week keeping temperature predominantly near to slightly below normal. Modification of the upper level flow with more substantial ridging will bring much warmer air into the Ohio Valley for next weekend and beyond.

Through Sunday

A scattered to broken cu field was present over much of the forecast area early this afternoon in the wake of the rain from Friday evening into early this morning. Despite the cu...temps had warmed nicely with mid and upper 60s across the region at 17Z.

Relatively quiet weather will continue through the rest of the weekend as the Ohio Valley remains heavily under the influence of the strong upper level low across northern Ontario. A weak wave rounding the base of the parent low in tandem with a surface trough will bring the opportunity for a few showers from late today into Sunday with the possibility of a couple rumbles of thunder this evening across northeast portions of the forecast area.

Cu will slowly decrease in coverage through late day as deeper low level moisture moves away from the region. Convection will develop across lower Michigan and into the eastern Great Lakes by late afternoon in the vicinity of an axis of slightly stronger MLCAPE. There remains the possibility that the tail of the convection may graze the far northeast part of the forecast area this evening. Model soundings do show subtle instability and steep mid level lapse rates that could present a narrow opportunity for a few stronger cells in the 00-04Z window despite limited low level moisture.

Beyond that the surface trough will sag into the forecast area overnight but once the lapse rates aloft weaken with the limited moisture present...hard to justify more than just isolated showers through early Sunday with most locations remaining dry. Mid and high level clouds will decrease from the north on Sunday as high pressure builds in from the upper Midwest and the surface trough shifts into the Tennessee Valley. Overrunning moisture along the remnant trough by late day Sunday may enable isolated light showers to briefly slip back into far southeast portions of the forecast area into Sunday evening but the overall trend will be towards dry conditions. Surface flow will veer to northerly late tonight and persist Sunday.

Temps...with the cloud cover lows tonight should largely hold into the lower and mid 50s. Low level thermals support highs Sunday roughly 5-7 degrees cooler than temperatures this afternoon. Expect mid and upper 60s for much of the forecast area.

Sunday Night through Wednesday

With the departure of the surface trough and associated moisture to the south...high pressure over the upper Midwest will become the primary feature influencing weather over the Ohio Valley for Monday and much of Tuesday. The airmass is cooler behind the surface trough but not overtly so with low level thermals supporting highs mainly in the 60s on Monday. The presence of light flow as the center of the high passes through early Tuesday could enable a patchy frost risk...perhaps our last of the Spring season based on trends... focused over the northeast portions of the forecast area. Return southwesterly flow on the back side of the departing high will advect warmer air into the region for Tuesday with highs closer to normal in the upper 60s and lower 70s. A tightening surface pressure gradient Tuesday in advance of an approaching cold front from the northwest will provide for a breezy day as well.

Convection will accompany the aforementioned front as it tracks into the area Tuesday evening...but the lack of substantial moisture return ahead of the boundary and timing of main impacts during the evening and overnight will limit overall convective coverage and intensity across the forecast area. A potent upper wave in tandem with a 40kt 850mb jet however will likely be sufficient to maintain convection through the night. Rainfall amounts into Wednesday morning should be generally at a half inch or less with locally higher amounts tied to any heavier showers or storms. High pressure will reestablish Wednesday with temps a shade cooler than Tuesday as cyclonic flow aloft sets up with a new upper low developing to our north.

Wednesday Night into Next Weekend

High pressure will shift east across the area Thursday with the upper low weakening and moving off the East Coast. A warm front will follow in its wake for late week with a transition to much warmer air for next weekend. Growing confidence in highs into the lower and mid 80s would be the warmest daytime temps for the forecast area since April 23. Cannot rule out isolated diurnally driven convection for Friday into next weekend.

Beyond next weekend...there appears to be the potential for one more stretch of seasonably cooler temperatures in the 60s and lower 70s for 2-3 days during the week of May 18 behind a cold front. Otherwise...the upper level flow regime is increasingly supportive of warm and largely dry weather for the Ohio Valley for the latter half of May with a likely return to multiple days with highs in the 80s.

AVIATION (18Z TAF Issuance)

Issued at 1227 PM EDT Sat May 9 2026

Impacts:

- W/SW wind gusts up to 25kts through the afternoon - Isolated showers tonight should cause no issues at terminals - Winds veering to northerly Sunday

Discussion:

Stubborn stratocu deck from earlier has largely mixed out into a cu field early this afternoon but with bases still at MVFR levels. Expect that to rise back to VFR in short order with cu gradually diminishing in coverage by late day. W/SW winds will gust up to 20- 25kts at times through about 22-23Z.

A weak surface trough will slip into the region tonight into early Sunday but lacks substantial low level moisture. Isolated convection may develop ahead of that late today into the evening but is expected to remain to the northeast of the terminals. A few light showers are possible overnight into early Sunday but coverage is anticipated to be so sparse that no mention is needed in the TAF forecast at this time. Mid and high clouds will begin to shift south Sunday morning with northerly flow as high pressure expands south from the upper Midwest.

IND WATCHES/WARNINGS/ADVISORIES

None.