textproduct: Indianapolis

KEY MESSAGES

- Rain returns tomorrow morning with showers and a few storms through the early afternoon

- Daily chances for showers and storms Tuesday through the rest of the week with near to slightly above normal temperatures

DISCUSSION (This evening through Saturday)

Issued at 1258 PM EDT Sat May 23 2026

Overview.

An unsettled and complex weather pattern remains established across central Indiana for the holiday weekend. Following a dreary day today, the primary focus shifts to an approaching upper-level disturbance that will bring another round of showers and isolated thunderstorms on Sunday. For residents and visitors planning outdoor activities, the main takeaway is that while the entire day will not be a washout, a window of wet weather is highly probable during the morning to early afternoon hours. Looking beyond the weekend, a transition toward a warmer and generally more stable pattern with broad ridging and daily low chances for afternoon showers and storms.

Tonight through Sunday.

Residual low-level moisture from a departing surface low-pressure system will keep skies partly cloudy across central Indiana tonight. Low temperatures will drop into the upper 50s with only minimal chances for a stray shower.

On Sunday, a more potent upper-level trough will swing through the region, driven by the southern periphery of the polar jet stream moving across the Great Lakes along with the ingestion of a diabatic low currently developing across Oklahoma into the broader jet flow. These features will supply broad vertical lift over the state with the main uncertainty being the exact timing of the better lift and duration of the rain. The morning model runs have continued a trend that began yesterday with a later arrival of the initial showers and storms with less of a second round towards the late afternoon with the aforementioned diabatic low creating a messier spread of showers and storms vs a more organized line of convection.

With that in mind, will be adjusting the POPs try and capture that timeframe of highest confidence with less of a bimodal distribution. Confidence is currently highest in a timeframe of 10AM-2PM being the greatest potential for rain with lesser chances both earlier in the morning and later into the afternoon. The severe weather threat will be marginal at best without a more potent shortwave but with bulk shear values around 25-35 kts and 500-700 J/kg of instability, at least isolated thunderstorms look likely.

Sunday Night through Saturday.

Precipitation will taper off quickly from west to east late Sunday as the upper-level trough axis departs. However, the associated weak surface frontal boundary is projected to stall just south of the Ohio River. This proximity will keep a low probability for lingering showers across the southern tier of Indiana through Memorial Day. Farther north, expanding surface high pressure over the Great Lakes will promote clearing skies and a pleasant start to the holiday. Temperatures will begin an above-normal trajectory, with afternoon highs climbing into the lower 80s.

For the remainder of next week, latest ensemble guidance show decent consensus regarding a transition to a quieter upper level pattern across the Ohio Valley with the polar jet shunted well north into Canada and the subtropical jet further south into Mexico with weak but broad ridging across the Central US. This will keep forcing and thunderstorm chances to be driven more by mesoscale factors such as boundaries along with a stronger diurnal curve to the storm chances.

Confidence decreases slightly heading into next weekend as ensemble means suggest the ridge axis may begin to break down as a stronger upper level low develops across Southeastern Canada. There remains a fair amount of spread as to the strength of this system and how much it influences the weather across the western Ohio Valley with the potential for more northerly surface flow which could bring a return to near to slightly below normal temperatures if that solution pans out.

AVIATION (18Z TAF Issuance)

Issued at 1258 PM EDT Sat May 23 2026

Impacts:

- Continued slow improvement in cigs from IFR to MVFR and eventually VFR - Return in MVFR to IFR cigs late tonight, potential for IFR vsbys - Rain likely after 14Z

Discussion:

Cigs will continue to slowly rise through the remainder of the afternoon with predominately MVFR cigs after 19Z and VFR towards 21Z. MVFR to IFR cigs likely return towards daybreak tomorrow along with the potential for patchy fog bringing IFR vsbys. Showers with embedded thunderstorms are then likely during the late morning and early afternoon hours with a 2-3 hour window of rain. Details remain uncertain on exact timing. Winds will remain westerly at 7-11kts through much of the TAF period before becoming more southerly towards 15Z tomorrow.

IND WATCHES/WARNINGS/ADVISORIES

None.