textproduct: Indianapolis

KEY MESSAGES

- Periodic showers with embedded thunderstorms today, especially across the southern half of central Indiana

- Briefly dry then scattered showers and storms return late Friday into Saturday

- Cooler through Friday with warmer temperatures returning this weekend into early next week

DISCUSSION (Today through Wednesday)

Issued at 233 AM EDT Thu Sep 10 2026

Showers and embedded thunderstorms will impact the region for much of the day as a wave of low pressure rides along a frontal boundary across the southern half of central Indiana. The front will shift south and wash out by Friday but remnant moisture will interact with a weak upper low to produce additional chances for rain across the Ohio Valley Friday night and Saturday.

Upper ridging will flex back into the area this weekend and into early next week with warm temperatures. A more organized threat for rain and storms will accompany a cold front on Tuesday with cooler air following for the second half of next week.

Today through Saturday

After a largely quiet first half of the night...scattered convection was developing across the lower Wabash Valley early this morning ahead of a cluster of storms moving east of KSTL. Temperatures at 06Z were in the upper 60s and lower 70s with patchy fog developing as well.

The developing convection early this morning is being aided by increasing warm advection and 850mb flow on the south side of a quasi-stationary boundary located just south of I-70. Expect a steady increase in coverage as an ongoing convective cluster over southern Illinois shifts east through the predawn hours. With PWATs near 2 inches currently across the southern portions of the forecast area and a front that will move little over the next several hours...storms will be efficient rainfall producers as they track across the southern tier of counties from Vincennes to Seymour through daybreak with lighter rainfall rates further north.

The first area of shower and storms will move east but once the front pushes further south...winds will shift to northerly. of the forecast by late morning but will likely be followed by a second cluster currently across eastern Kansas and western Missouri and poised to track into the southern half of the forecast area this afternoon. The arrival of an upper wave from the northwest will buckle heights aloft and should allow for the frontal boundary to resume southward progression during the afternoon. The heaviest rainfall rates with the afternoon storms may just graze far southern counties and focus more across far southern Indiana into Kentucky where a more unstable airmass will reside. Regardless...rain chances will linger for much of the day with an abundance of lower clouds.

Clouds will diminish from the north tonight as weak high pressure and deeper subsidence expand into the area. Patchy fog may again be a factor for early Friday with near calm winds even as drier air advects into the region. The aforementioned frontal boundary will wash out south of the Ohio River on Friday leaving an axis of remnant moisture. As a developing upper low lifts into the mid Mississippi Valley late Friday...the moisture will be pulled back north into the area with scattered showers and storms impacting the southeast half of the forecast area in particular Friday night into Saturday as the upper low pivots across the region.

Temps...clouds and rain today will keep temperatures closer to early September normals in the upper 70s and lower 80s with similar readings for Friday as well. The resumption of return southerly flow for Saturday will bring a warmer and subtly more humid airmass back into the area with mid 80s.

Saturday Night through Wednesday

The deeper moisture plume will shift east of the region Saturday night as ridging aloft expands back north for late weekend. This will stall a weak frontal boundary to our north over the lower Great Lakes before lifting back north as a warm front early next week in response to low pressure developing over the High Plains. This will allow for a brief return of a hotter and more humid airmass with highs climbing back to near 90 degrees Monday and Tuesday across the southern half of the forecast area.

The aforementioned surface low will track into Ontario on Tuesday pulling a cold front into the region with a better chance at showers and storms. Model trends are now supporting the boundary becoming nearly stationary across the Ohio Valley through the middle of next week as it runs into the retreating upper level ridge to the south. The boundary may linger until a much stronger cold front running in tandem with a sharp upper level wave dives through the area late next week. In the wake of this frontal passage...the first opportunity for a cooler early Fall airmass is becoming increasingly likely for the region by next weekend.

AVIATION (12Z TAF Issuance)

Issued at 549 AM EDT Thu Sep 10 2026

Impacts:

- Occasional showers with embedded thunder today - MVFR ceilings possible late morning through the afternoon - Patchy fog early Friday

Discussion:

Showers are moving across central Indiana early this morning with thunderstorms just south of KBMG. This area of rain will move east of the terminals this morning with an additional rain and embedded thunder set to spread into the area for the afternoon. Showers will linger through late day but gradually sink south of the terminals with a frontal boundary this evening.

Model soundings and RH progs both highlight an expansion of MVFR stratus later this morning that will linger into the afternoon with showers. Lower clouds will move out this evening with ceilings lifting tonight as drier air advects in from the north. Winds will be light and variable for much of the day then shift to light northeast tonight. Patchy fog is likely to develop in the predawn hours on Friday.

IND WATCHES/WARNINGS/ADVISORIES

None.