textproduct: Indianapolis

KEY MESSAGES

- Hot and humid through at least mid week

- Near daily chances for showers and storms

- At least an isolated severe threat at times late Sunday into late Wednesday, with damaging winds and localized flooding the primary threats

DISCUSSION (Today through Friday)

Issued at 313 AM EDT Sat Aug 8 2026

TODAY AND TONIGHT

A remnant outflow boundary from yesterday that triggered widely scattered convection through the early overnight continues to linger across the region, though it has washed out somewhat. A subtle shortwave disturbance aloft will slowly pass through the region today, and this may combine with the presently warm and very humid airmass to produce additional isolated to widely scattered convection, mainly this afternoon into early evening, before subsidence behind the weak wave and slightly drier air moving into the area with surface high pressure combine to bring at least a brief end to rain chances.

A cap of varying strengths is noted in forecast soundings centered around 850 mb, and this along with relatively weak shear will be the primary limiting factor on storms today. An isolated weak downburst or small hail will certainly be possible in any storms that can sustain themselves, but the primary concern will be heavy downpours and localized flooding, particularly in areas that have received significant rainfall in the past several days.

Highs today should be at or just below persistence today, in the mid to upper 80s, with a 90 degree reading not out of the question south. The slightly drier air will allow lows tonight to drop down into the 60s across the area.

Surface high pressure will produce light to calm winds tonight, and expect areas of fog, perhaps dense in spots, to form late in the evening into the overnight hours.

SUNDAY ONWARD

Broadly speaking, warm and humid conditions will continue through mid week, with some moderation in daytime highs late in the week, as a broad upper level ridge persists from the southeastern into the western CONUS. The hottest conditions will be early in the week, with highs Sunday through at least Tuesday well into the 80s or low 90s across central Indiana, and heat index values possibly peaking in the mid 90s to low 100s each day, though convection potential increases the uncertainty with respect to this. While we appear unlikely to reach strict heat advisory criteria at any point, at least moderate heat risk is likely through mid week, and major heat risk is likely to nudge into the area on one or more days, though again, convection significantly complicates predictability of this.

Thunderstorms will be a threat for at least portions of the area each day, though PoPs will be highest Tuesday into Thursday, when a weak surface front and more substantial upper level disturbances on the periphery of the ridge come into play.

There will be at least a low threat for severe storms each day from Sunday through Wednesday, with significant uncertainty with respect to exact areas and timing owing to the inherent low predictability of weakly forced warm season convection, which is largely thermodynamically/cold pool driven. In any case, damaging winds will be the primary severe threat, with of course a continued concern for heavy downpours and localized flooding as highly efficient rain rates will remain a concern with seasonably high freezing levels and precipitable water values at or at times well above normal, and some areas seeing substantial rain in recent days.

Though chances for showers and storms will persist beyond mid week into the latter portion of the week, a more moderate airmass will cut down on available instability and result in more limited severe threat beyond mid week. Run to run model consistency in recent days has been somewhat poor, though, so stay tuned in this regard.

AVIATION (06Z TAF Issuance)

Issued at 115 AM EDT Sat Aug 8 2026

Impacts:

- Periods of fog likely near daybreak, primarily at the outlying sites

- Low chance for showers/storms

Discussion:

Light and variable winds and very humid low levels will again set the stage for periods of fog near daybreak, with TEMPO IFR conditions possible at the outlying sites. Dense fog is certainly briefly possible, but is low confidence.

Any fog will mix out quickly post sunrise, with broken VFR cumulus expected. There will be a low chance for showers or storms today, but these chances will be higher east of the sites and are too low/uncertain for mention in the TAF at this point.

Winds will be light and variable to calm at times overnight, becoming westerly at 7-9KT gusting occasionally to 14-17KT depending upon the site.

Calm winds and clearing skies are expected Saturday night, which may set the stage for additional fog.

IND WATCHES/WARNINGS/ADVISORIES

None.