textproduct: Indianapolis

KEY MESSAGES

- Visibility reductions in patchy fog through 8-9 AM this morning

- Quiet pattern continues through Wednesday amid light winds and near to slightly below normal temperatures/humidity

- Generally humid, seasonably warm w/occasional rain/storm chances Wednesday night into next week...rain most likely Thursday-Friday

FORECAST UPDATE

Issued at 1019 AM EDT Tue Aug 4 2026

Surface high pressure remains directly overhead and will lead to a quiet day today. Winds are expected to be nearly calm this afternoon, picking up out of the southeast later today as the high shifts eastward. Cloud cover will be limited to diurnal cumulus and some high cirrus from upstream convection. Our primary forecast challenge today looks to be temperatures and dew points. Boundary layer mixing is expected to be efficient today, and guidance typically under does its effects due to various resolution and microphysical limitations. IND ACARS soundings show a very dry and subsident atmosphere just above the surface. Assuming efficient mixing, this dry air should have little trouble making its way to the surface. We will lower dew points today (under the 25th percentile), adding more weight to the HRRR which tends to capture these effects well. Additionally, we will nudge temperatures upward a bit for the same reason.

DISCUSSION (Today through Monday)

Issued at 302 AM EDT Tue Aug 4 2026

Today and Tonight...

The short term will present a near-carbon copy of the previous 24 hours as weak surface high pressure continues to drift east within the northeastern quadrant of the CONUS...while maintaining its low- gradient and narrow axis over central Indiana. Expect areas of fog to present patches of quick changes in visibility through 8-9 AM EDT...albeit less organized than early Monday, courtesy of the August sun drying ground moisture through the early week. Otherwise the period will be marked by unseasonably light winds and slightly below normal temperatures and humidity.

Mainly clear skies early today will again trend to an increasing cumulus field by afternoon...with highs this afternoon ranging from the low 80s along and northeast of the I-74 corridor...to mid-80s near and south/west of Monroe County. Fair weather will continue into tonight amid calm winds under mostly clear skies. Expect overnight lows to range from 59F near Kokomo to 64F in Vincennes and Seymour.

Wednesday...

Influence from an upper low to the southeast of central Indiana looks to remain out of the area, and forcing from an approaching upper trough/surface cold front will remain northwest of the area during the day. Will continue a dry forecast.

Highs will generally be in the middle 80s.

Wednesday night through Saturday...

The large upper trough will move into the area at into Saturday. Various shortwaves will move through this trough, with the axis of the trough not moving through until about Saturday. These will bring rounds of forcing. At the surface, a front will meander near the area. The combination of these will be enough to keep PoPs around through this period.

Although some uncertainty remains in the timing of the best forcing, for now odds still favor Thursday afternoon and night.

Dewpoints returning into the 70s by Friday will help increase the instability, but odds for severe storms look low for now. Will continue to keep an eye on it though in case one of the shortwaves becomes stronger than currently expected.

Sunday and beyond...

The upper ridge across the western USA may nudge its way into the area on Sunday into early Monday, lowering the chances for rain. However, by Monday night it may retreat enough to put central Indiana in line to get convection from storms riding around the ridge.

Highs will be in the middle and upper 80s, with perhaps some readings around 90 south depending on what the ridge does. With the higher dewpoints in place, heat indices may approach 100 degrees on Monday.

AVIATION (12Z TAF Issuance)

Issued at 711 AM EDT Tue Aug 4 2026

Impacts:

- MVFR in fog possible through 13Z...and most likely at KBMG

Discussion:

Calm to very light winds will promote MVFR visibility in BR at KBMG...with brief MVFR possible at KLAF/KHUF. Weak surface high pressure will continue to drift east over the Midwest through the TAF period...maintaining calm to weak flow, most often from the east- northeast, under 10KT at KIND and under 7KT elsewhere.

Mostly clear skies will yield to FEW/SCT cumulus by this afternoon, with greater coverage at KLAF/KHUF.

IND WATCHES/WARNINGS/ADVISORIES

None.