textproduct: Indianapolis

KEY MESSAGES

- Areas of dense fog possible tonight

- Hot and humid conditions expected Sunday into Monday

- One or more thunderstorm complexes possible Sunday night and Monday night, with damaging winds and heavy rainfall the primary threats

DISCUSSION (This evening through Saturday)

Issued at 304 PM EDT Sat Jul 25 2026

This Evening through Sunday night...

Widespread low clouds will continue across the area this afternoon into this evening, along with a few sprinkles or light showers during the daylight hours, as a warm front approaches and a subtle shortwave passes through the area. Some clearing may occur this evening before ample low level moisture in the presence of both a stout inversion aloft and the aforementioned boundary, along with light to calm to surface winds, promotes the redevelopment of low clouds and fog, which may become dense in spots late tonight.

Cloud cover and fog may be slow to mix out tomorrow underneath the aforementioned inversion, courtesy of a stout elevated mixed layer, but we should see breaks of sunshine by midday as the boundary moves further into the region and PBL mixing increases. The inversion will keep a strong lid on an otherwise fairly strongly unstable airmass through the day, with chances for thunderstorms increasing during the evening and into the overnight hours Sunday night.

Plentiful instability and shear will be present, though significant uncertainty exists regarding exactly where upstream thunderstorm activity will initiate, how exactly these storms will organize, and the orientation of the instability gradient that will largely drive their motion. CAMs are struggling to converge on a scenario, which is not surprising given the pattern and time of year. A wide envelope of scenarios exists for tomorrow night into early Monday, from little to no convection, to a potent QLCS pushing into the area with damaging wind potential.

Temperatures will depend heavily upon clearing tomorrow and thunderstorm activity tomorrow night, so uncertainty is higher than would prefer, but assuming we see good sun tomorrow afternoon, highs will likely rise well into the 80s, with overnight lows limited by dewpoints largely to the low 70s.

Monday and Monday night...

Chances for convection will be higher late Monday into Monday night, as somewhat more strongly forced scenario is likely with both a surface cold front and shortwave trough supporting thunderstorm development. However, uncertainty still remains high in the exact timing and details, given the influence that potential prior convection will have on subsequent episodes, and the heavy dependence upon the thermodynamic parameter space for determining exactly how and where these MCSs will impact. Suffice to say, plentiful instability and shear will likely be present across the region, and any storms that move into the area will possess potential for damaging winds. Additionally, precipitable water values will approach 2 inches at times, which along with deep and efficient warm rain processes may set the stage for heavy rainfall and localized flash flooding.

Temperatures are again uncertain owing primarily to convective potential, but highs well into the low to mid 90s are definitely on the table Monday, which could drive afternoon heat index values well into the triple digits in spots.

Tuesday onward...

Cold frontal passage Monday night into early Tuesday will bring temperatures back down closer to seasonal normals from mid week onward, with a largely dry forecast until very late in the week as surface high pressure dominates the area. As the ridge aloft retrogrades slightly, upper level disturbances late in the week may promote rain chances, though significant disagreement on these systems precludes more than a slight chance at this point.

AVIATION (00Z TAF Issuance)

Issued at 750 PM EDT Sat Jul 25 2026

Impacts:

- Generally widespread MVFR/worse through at least 15Z...with periods of low-VFR this evening, especially at KIND - Deterioration after 06Z to IFR/worse from west to east outside of KIND, due to both stratus and BR/FG - LIFR possible 09Z-13Z, mainly at KLAF/KHUF

Discussion:

Warm advection amid pattern change to very warm/hot conditions by end of TAF period...will promote thickening low clouds and BR/FG tonight outside of KIND, and especially over western central Indiana. Lower confidence in LIFR from VIS given lowering ceilings...but higher certainty in IFR/worse at KLAF/KHUF/KBMG within 09Z-14Z Sunday. VFR expected to return by Sunday afternoon.

Winds to be calm or light/variable for most of tonight...with S/SSW winds under 7KT possible through 03Z.

IND WATCHES/WARNINGS/ADVISORIES

None.