textproduct: Indianapolis

KEY MESSAGES

- Quiet weather with near normal temperatures today and tonight

- Showers and thunderstorms return late on Friday and continue through the weekend. There is an excessive rainfall threat Friday night through Saturday for most of central Indiana.

- Warming trend likely for the first week of August

FORECAST UPDATE

Issued at 936 PM EDT Thu Jul 30 2026

No major changes necessary to this evening's forecast, aside from a very brief patchy fog mention in the outlying areas near daybreak. Fog should be more limited in coverage and density than recent mornings owing both to additional high cloud and two days worth of plentiful sunshine helping to dry the ground, but surface high pressure being directly overhead and widespread calm to light and variable winds suggest at least a patchy mention is still prudent. What fog does develop will quickly mix out post sunrise. Lows will likely drop down to the low 60s across the area, limited mainly by the aforementioned high cloud and dewpoints. An isolated reading in the upper 50s would not be out of the question.

DISCUSSION (This evening through Thursday)

Issued at 116 PM EDT Thu Jul 30 2026

Surface high pressure has built into the region and a cool and a dry air mass is in place. Temperatures have risen into the low-mid 80s and dew points have dropped into the mid 50s in a few places. Efficient boundary layer mixing has allowed dew points to fall below guidance (as low as the 5th percentile). Additionally, high temperatures may run a few degrees above guidance. Still, near average readings are expected this afternoon.

Surface high pressure along with light and variable winds may allow for patchy fog tonight like previous nights. However, increasing high cloud cover tonight may limit coverage in comparison. Fog is most probable along rivers and in rural/agricultural areas.

Aloft, troughing over the northeastern US will promote northwesterly flow across the Midwest. Ensemble guidance is in good agreement showing a shortwave trough diving southeast within this flow, arriving later Friday evening. Showers and thunderstorms are possible as early as Friday night. Guidance then slows the shortwave down as western ridging amplifies. This should bring higher rain probabilities into the day Saturday, potentially into early Sunday. Locally heavy rainfall amounts are possible owing to the slow system motion.

Looking into next week, the weekend shortwave departs eastward while the polar jet lifts north. Though there is no strong signal for either troughing or ridging, the jet stream residing well to our north should allow temperatures to creep upwards. A warming trend is therefore favored next week with highs potentially reaching into the upper 80s / near 90 at times. Some guidance keeps the jet stream active, with frequent storm systems embedded within the broader flow. This may act to keep daily precipitation chances above average through next week as well. However, the signal regarding precipitation is less clear than for temperatures.

AVIATION (06Z TAF Issuance)

Issued at 1248 AM EDT Fri Jul 31 2026

Impacts:

- Mainly VFR this period.

Discussion:

VFR conditions expected through the TAF period.

Weak surface high pressure was found over Central Indiana early this morning. A low pressure system over SE NB was allowing advection of mid and high clouds into Indiana, resulting in VFR Cigs. Dew point depressions across Central Indiana remained quite low. Given this and light to calm winds, patchy fog will be possible toward daybreak, especially at the more rural TAF locations.

On Friday, the upper low will begin to approach Central Indiana an ongoing invasion of mid and high clouds will arrive through the course of the day. HRRR suggests a wave of showers ahead of this low passing into Indiana after 010000Z. Confidence is high for the occurrence of rain, however, confidence is low for precise timing and locations. Nonetheless, a large window of VCSH will used toward and after 00Z. Mainly VFR cigs will be expected with the showers.

IND WATCHES/WARNINGS/ADVISORIES

None.