textproduct: Indianapolis

KEY MESSAGES

- Hot and humid through at least mid week, with daily chances for showers and storms...especially through Friday morning

- Multiple rounds of severe storms will be possible from early today through at least Wed night...w/damaging winds, heavy rainfall/flash flooding the primary threats

MESOSCALE UPDATE

Issued at 306 AM EDT Mon Aug 10 2026

Smaller yet severe mesoscale convective complex currently crossing into northwest Indiana will enter northern portions of the IND CWA through pre-dawn hours. While overall slow weakening is expected, damaging winds are possible for the Lafayette area and east...with non-zero chances of isolated large hail or a brief, weak tornado. This convection is expected to cross northern counties through 13Z.

Previous mesoscale discussion follows...

Fairly robust convective development has occurred in the past 90 minutes over northwest Illinois along and south of a quasi- stationary front and at the nose of a WSW 25-35KT low level jet associated with a weak shortwave disturbance aloft. Sufficient effective deep layer shear exists in and upstream of central Indiana to support storm organization, with the most likely scenario being initial supercells growing upscale into one or more line segments that push eastward, then gradually more east/southeastward with time through the night. Significant uncertainty exists with how far southward the influence of the complex will extend, but roughly the northeastern third to half of the area, along and NE of the I-74 corridor, appear to have the greatest threat for strong to severe storms during the overnight hours.

Modest effective SRH values suggest a non-zero tornado threat, but upscale growth will likely support primarily an isolated damaging wind threat, and strongly supportive environmental factors (PWAT values around climatological 90th percentile, high freezing levels/deep warm rain processes, and possibly training convection along the upshear flank of the system) will support a threat for heavy rainfall and localized flooding as well. HREF local probability matched means show potential for isolated 1-3 inch amounts, with higher amounts possible in the strongest cores or if/where training occurs.

DISCUSSION (Today through Sunday)

Issued at 316 AM EDT Mon Aug 10 2026

Early today through Wednesday...

Central Indiana will continue to rest amid the northeastern edge of a predominant subtropical ridge occupying most of southern North America...with seasonably modest northwest flow aloft and associated small/weak forcings...maintaining chances of occasional convective clusters. Additionally, a weaker yet broad trough of surface low pressure aligned from the central Plains across the northern Midwest, will promote moderate southwesterly breezes...bringing very warm to hot conditions and increasingly oppressive humidity into the mid-week.

The resultant higher theta-E will contribute to instability gradient, although this will likely be strongest along the local region's far northern/NE zones...if not even closer to the southern Great Lakes. Therefore convective chances within the CWA will be greatest following upstream development (northern IL) that then trends/curls SE-ward. Best chances for organized/severe storms will most likely be Tuesday PM-overnight hours, and again late Wednesday...with general focus I- 74 corridor and northeast, with lowest confidence on severe potential over southwest counties.

That said, cannot rule out isolated RW-s at overall less favorable times given the warm/humid boundary layer...including isolated thunder later today north of a Lafayette to New Castle line, and across much of the CWA tonight. Expect temperatures through Wednesday to range from 68-75F to 85-93F, with a distinct NNE-SSW gradient, which may be increased by greater cloud cover over NE counties Tue-Wed.

Thursday through Monday...

Remainder of the period to most likely feature see-saw of conditions as quasi-stationary surface cool front along the northern side of very broad and very humid subtropical ridge...probably slides south by late Thursday, placing the region in milder easterly flow...with the boundary expected to then push north, returning humid southerly flow for the weekend. Most periods to yield at least low POPs per the corresponding frontal zone never really pushing south of the CWA, although overall convective chances after Thursday night should be much lower than the early/mid-week. Readings to range from mainly 60s to 80s.

AVIATION (06Z TAF Issuance)

Issued at 155 AM EDT Mon Aug 10 2026

Impacts:

- Convection possible 08Z-14Z at KLAF/KIND...and after 00Z Tuesday, especially near KLAF/KIND MVFR conditions possible at times within storms

- Near LLWS conditions at KLAF through pre-dawn hours

- South-southwest winds gusting up to 15-20KT within 12Z-22Z

Discussion:

VFR to prevail near central Indiana terminals outside of convection through Monday evening. Current upstream convection most likely to impact KLAF around 08Z-11Z with lower chances of MVFR from -TSRA at KIND around 10Z-14Z...VFR expected to continue at KHUF/KBMG through Monday morning. A second convective cluster is possible, most likely after 02Z Tuesday.

Otherwise expect near-LLWS conditions over KLAF around the 10Z-12Z timeframe. Generally south-southwest surface winds will remain near or just below 7KT/10KT thresholds through 11Z outside of any cells. Flow to increase to 8-13KT by 16Z, with gusts up to 15-18KT by 15Z, peaking 15-20KT around 16Z-20Z.

A few gusts near 20kt are possible later this afternoon. Increasing winds aloft will bring near LLWS conditions tonight but have not included a mention in TAFs at this time.

IND WATCHES/WARNINGS/ADVISORIES

None.