textproduct: Indianapolis

KEY MESSAGES

- Flood Watch in effect through 8AM today across the northern half of central IN with localized flash flooding possible

- Scattered to numerous showers and storms to slowly depart south through the early morning hours

- Generally drier late this week through early next week, but there is a chance for showers and storms late Friday into Saturday

DISCUSSION (Today through Wednesday)

Issued at 315 AM EDT Thu Aug 20 2026

Early This Morning...

Following a surprisingly potent quasi-linear convective system that twisted from the western I-70 corridor down to the I-69 corridor immediately south of Indianapolis through the wee hours...a few non- severe cells amid overall scattered convection, will continue to track to the east-southeast into pre-dawn hours. Localized flash flooding will continue to be the greatest threat...as is the case in the Putnam County to northwestern Morgan County area from the recent cell whose head sat and spun over these counties while producing heavy rainfall rates. Locally dense fog will be another concern towards daybreak...with deteriorating visibility trending from NW to SE. Most of the storms and heavier showers should be south of the area by 12Z (8 AM EDT).

Today...

Will keep some low PoPs going early today in the far south to account for any lingering rain.

Otherwise, outflows from previous convection will be south of the area today, but the cold front might still ignite isolated showers or storms this afternoon in the far south part of central Indiana. Better shear should be south of the area, so severe storms are not expected.

Most of the drier air won't arrive until tonight, so it will still feel humid. Highs will be in from around 80 to the lower 80s.

Tonight and Friday...

Surface high pressure will build in and provide quiet weather during this period. Slightly drier air will briefly move in tonight, but upper 60s dewpoints could return by Friday afternoon. Lows will be in the lower to middle 60s tonight with highs in the lower to middle 80s on Friday.

Friday night into Saturday...

An upper wave will help push a cold front through the area during this time. Current expected timing has storms moving in Friday night and likely weakening as they move in. Storms then redevelop Saturday afternoon, mainly east as the front moves through and exits. Of course will have to monitor in case timing of the system changes. Depending on the timing of the front and rain, highs on Saturday may only be in the upper 70s north to middle 80s south.

Saturday night through Tuesday night...

Surface high pressure will likely dominate during this period, providing dry weather. Northwest flow will keep hot air well west of the area, and central Indiana will see near to below normal temperatures. Lows in the 50s will become widespread by Sunday night, with highs generally in the mid 70s to lower 80s.

Wednesday onward...

Another upper wave/surface cold front will move through around Wednesday. Best moisture will be kept south of the area, so for now will only have some low PoPs. Seasonable temperatures are expected.

AVIATION (06Z TAF Issuance)

Issued at 1252 AM EDT Thu Aug 20 2026

Impacts:

- MVFR to IFR cigs and vis from fog at times through 13z - Rising cigs and improving conditions today - Chance of fog at KLAF, KHUF, and KBMG after 06z tonight.

Discussion:

Latest satellite and radar imagery shows earlier convection is now south and east of all terminals, with areas of MVFR to IFR cigs and vis in its wake. Best chance at fog this morning remains in the Wabash River Valley before 13z. Expect rising cigs later this morning as high pressure settles in from the north and drier air advects in. Cigs this afternoon should be largely VFR as afternoon cu develops. No wind issues today as light and variable winds this morning become northerly below 10 kts this afternoon. Leftover moisture trapped near the surface may lead to fog develop after 06z tonight within the Wabash River Valley with periods of MVFR or worse conditions possible.

IND WATCHES/WARNINGS/ADVISORIES

Flood Watch until 8 AM EDT this morning for INZ021-028>031- 035>049-054>057.