textproduct: Indianapolis

KEY MESSAGES

- Quiet pattern lingers today, more summerlike humidity and warmth by this afternoon

- Rain and storms chances return tonight and linger into early next week, with greatest chances Thursday and Friday

- Localized flooding will be possible at times from repeated rounds of convection

- A few strong/severe storms are possible this weekend into early next week...with low confidence on exact details

DISCUSSION (Today through Tuesday)

Issued at 404 AM EDT Wed Aug 5 2026

Today through Thursday night...

Last portion of recent quieter, yet summery pattern will linger through this afternoon as modest surface high pressure finally exits east. Broad and stronger early-autumn H500 trough spinning over western Hudson Bay, and sending solid Canadian air into the Upper Midwest...will twist a couple weaker vorts along its southeastern periphery over the Midwest into the late workweek. This mild forcing along with a weaker low-level jet will slowly shift noticeably better moisture just to our northwest...into at least the Wabash Valley tonight, with perhaps a couple widely scattered showers getting as far as the northwestern two-thirds of the CWA Thursday. However, latest trends suggest coverage/intensity of any showers to trend downward Thursday as soon as mid-level support slides east of the region.

Nevertheless, areas northwest of a Rockville to Kokomo line can expect more scattered shower coverage from late this evening into at least Thursday morning, where isolated storms could have a could robust gusts...with low chances of a few disorganized t-storms far southeast along the I-69 corridor. Lack of organized ridging and a rather damp column through the latter half of Thursday will still facilitate at least a few showers and a stray TRW. Another, more subtle wave with associated small bump up of precipitable water should enter the region Thursday night, so kept likely POPs for pre- dawn hours Friday, albeit with still lower confidence in any appreciable rainfall or stronger cells.

Dewpoints today should actually display a narrow minimum axis under the lingering ridge, with mid-60 values possible into early evening from Washington to Brown County to Muncie. Otherwise light southwest winds will bring more humid and warmer conditions with highs 83-89. Clouds Thursday to keep readings more moderated with higher humidity with highs mainly low 80s, and mid-80s for far south/southeast zones. Early morning minimums 65-70F through the short term.

Friday Through Saturday.

An upper-level shortwave trough currently traversing the Upper Midwest will drive a surface cold front south-southeastward into the Ohio Valley by Friday afternoon. Guidance from the latest GFS and ECMWF along with ensemble clusters shows the main upper-level dynamics lifting northeastward into eastern Canada, causing the surface boundary to lose upper support and become quasi-stationary across central Indiana. Deep tropical moisture transport will precede the front, with ensemble mean PWAT values exceeding 1.8 to 2.0 inches, which sits well above the 90th percentile for early August climatology.

HREF members indicate modest surface heating beneath cloud cover on Friday, yielding MLCAPE values between 1200 and 1800 J/kg by late afternoon. Kinematic forcing remains weak, with 0-6 km bulk shear generally around 15-20 knots, precluding organized severe convection. However, convective initiation along the front and lingering mesoscale outflow boundaries will produce multi-cell clusters capable of high precipitation efficiency. Given slow storm motion parallel to the surface boundary, localized training of storms and localized flash flooding remain the primary hydrologic hazards through Saturday evening before the main moisture axis finally pushes south into Kentucky.

Sunday Through Tuesday.

A broader synoptic pattern shift occurs Sunday as an expansive upper- level ridge over the central Plains expands eastward while a broader longwave trough settles across the northeastern US. This will establish northwesterly flow aloft across central Indiana. With broad ridging to the southwest, rain chances will mostly be limited to the central and northern counties through the period with weak shortwaves within the broader upper level flow. Daytime highs will remain near or slightly above seasonal normals in the mid to upper 80s, accompanied by very humid dewpoints in the low to mid 70s combining to bring a return to upper 90 to near 100 heat index values.

AVIATION (12Z TAF Issuance)

Issued at 705 AM EDT Wed Aug 5 2026

Impacts:

- MVFR/IFR in fog through 12Z-13Z

Discussion:

MVFR visibility possible at KHUF/KBMG through at least 12Z...with high confidence in widespread VFR across central Indiana by 13Z. Pattern to gradually transition over local region through the TAF period as narrow SW-NE axis of weak high pressure drifts across KIND and KBMG through late day...with increasing high/mid cloud over at least KLAF after 00Z this evening, although high confidence in CIGs staying in VFR levels through 12Z Thursday.

Likely VCSH leading to -SHRA after 01Z Thursday, with chances of isolated -TSRA too low to include in TAF at this time. Meanwhile VCSH across most of the territory between KLAF and KHUF/KIND after 06Z, but confidence too low for these terminals to mention before 12Z. Overall light winds to continue today with weak gradient surrounding approaching system...with gusts nearing 10KT at both KLAF 17Z-22Z today, and KIND after 16Z Thursday.

IND WATCHES/WARNINGS/ADVISORIES

None.