textproduct: Indianapolis

KEY MESSAGES

- Scattered thunderstorms expected to continue through Saturday night

- Localized heavy rain and minor flooding being the primary threats

- Drier and increasingly warm conditions late Sunday through the middle of next week as high pressure builds

FORECAST UPDATE

Issued at 1021 AM EDT Sat Jul 11 2026

Slow moving showers and some thunderstorms continue across portions of central Indiana this morning. An upper level impulse is interacting with a surface front in the area to produce the convection. High moisture content of the atmosphere is aiding efficient rainfall rates, which have produced at least between 2 and 3 inches of rain for portions of the area this morning.

The initial upper impulse will continue to move slowly east into early afternoon, continuing to produce the heavier showers and storms from about the Indy area eastward. Other scattered showers and storms will continue with broader, weaker forcing from the surface front and an upper level trough.

During the remainder of the afternoon, additional scattered to numerous showers and storms will develop as the front sags south and additional upper impulses move through. The most coverage should be south of I-70 as the front moves south, but will continue to monitor. Heavy rain will be the primary threat, but can't rule out an isolated strong storm if enough instability is able to build.

Sky cover should break up some this afternoon with breaks noted upstream. For now have left high temperatures alone but may have to nudge them down if cloud coverage remains high longer than expected.

DISCUSSION (Today through Friday)

Issued at 131 AM EDT Sat Jul 11 2026

Overview.

A quasi-stationary frontal boundary will keep thunderstorms in the area through Saturday night. Because these storms will move slowly and may repeat over the same areas, localized flooding will be the primary weather hazard. Rain chances afterwards look low with temperatures will be slightly above normal, averaging in the mid to upper 80s, but dew points are expected to remain in the upper 60s to low 70s which will limit the more extreme heat threat.

Rest of Tonight.

Low stratus and patchy fog are likely into the morning hours due to weak low-level wind fields and high residual low-level humidity. The 00Z HREF/REFS are honing in on an area mainly across Illinois, but stretching into southwestern Indiana where flood probabilities will be high with rainfall rates of 1-2 inches per hour at times. Some spotty 3 to 4+ inch rainfall totals will be possible given the slow storm motions. Will continue to monitor the radar trends and issue flood products accordingly.

Saturday Through Sunday.

The near-term synoptic pattern will be characterized by a quasi- stationary frontal boundary draped across the region, held in place by a flat sub-tropical ridge centered over the Gulf Coast states. Within this weak steering regime, successive low-amplitude mid-level shortwaves will track along the frontal zone and interact with a deeply saturated atmospheric profile with PWAT values near 1.5 to 1.8 inches. Mesoscale model guidance, including the HREF and its component members, show modest mid-level lapse rates and weak deep- layer vertical wind shear under 20 knots, which will limit overall storm organization and keep the severe weather risk low.

However, high precipitation efficiency within a deeply saturated profile raises the potential for localized heavy rainfall and training cells, especially towards south central Indiana. By Saturday afternoon, the front is forecast to be in the southern portions of the forecast area, shifting the primary convective focus to central and southern Indiana while the northern counties experience a gradual drying trend from north to south. By Sunday morning, rain chances will be limited to just the far southern counties with little to no rain chance towards I-70 and points to the north.

Monday through Friday.

Global ensembles, including the GEFS and EPS, are in good agreement in a broader synoptic pattern shift beginning Sunday. The departing upper trough will move eastward, allowing broad mid-level ridging over the central United States to expand into the Great Lakes and Ohio Valley. From Monday through Wednesday, strong large-scale subsidence beneath the core of the building ridge will suppress convective development entirely, keeping conditions dry across central Indiana. As the ridge axis centers over the area, low-level thermal profiles warm significantly, with 850 mb temperatures progged to reach 18-20C. This will translate to surface high temperatures rising from the upper 80s on Monday to near 90 by Tuesday and Wednesday. Surface dewpoints in the upper 60s to lower 70s will yield heat indices climbing into the mid-90s.

Toward Thursday, ensemble guidance hints at the ridge retrograding slightly toward the western United States, placing the Great Lakes into northwest flow aloft, which could introduce a weak northern stream shortwave and a return of convective chances late in the period. Confidence is low on details, but somewhere in the Ohio Valley will likely end up being impacted by convective clusters riding the ridge to the southeast.

AVIATION (12Z TAF Issuance)

Issued at 553 AM EDT Sat Jul 11 2026

Impacts:

-MVFR to briefly LIFR vsbys through 13Z due to fog -MVFR to IFR cigs through 15Z with low stratus -Chances for MVFR vsbys due to -RA through the day, mainly at BMG and HUF

Discussion:

Any lingering fog should dissipate by 13Z with low stratus persisting through mid to late morning. Occasional showers will continue through the morning before coverage increases in the mid to late afternoon. Chances are low at any given time, but confidence in any rain is highest at HUF and BMG. There may be a few thunderstorms as well, but confidence is low. Winds will generally remain northerly to northeasterly at 5-10kts through the TAF period.

IND WATCHES/WARNINGS/ADVISORIES

None.