textproduct: Indianapolis

KEY MESSAGES

- Heavy rain and severe storms are possible this afternoon into early Monday

- Flooding threat both river and non-river will increase with heavy rain on already saturated soils in some areas

- Below normal temperatures will continue for much of the period

FORECAST UPDATE

Issued at 926 AM EDT Sun Jun 21 2026

The forecast remains in great shape with only minor adjustments made. Current Regional Mosaics depict an MCS pushing across MO and parts of IL with a developing MCV. This complex of storms will continue to push eastward towards the area bringing the threat for severe thunderstorms and flooding late this afternoon into the overnight hours. More information regarding these threats can be found in the discussion below.

Much of the day will remain quiet before precipitation eventually arrives. Expect moisture advection to result in greater cloud cover through the day while also leading to rising dewpoints. Dewpoints in the 50s this morning should return well into the 60s to near 70F towards this evening. Look for winds to also gradually strengthen and become more southerly as the system approaches. Southerly flow will help warm temperatures well into the 70s to mid 80s.

DISCUSSION (Today through Saturday)

Issued at 251 AM EDT Sun Jun 21 2026

Today and Tonight...

This morning will be quiet with increasing cloudiness. A few showers are possible early this afternoon with some lift ahead of the main system.

Mid afternoon into the evening, an area of thunderstorms will move west to east across central Indiana. Mid and low level jets, an area of surface low pressure and associated warm front, and a Mesoscale Convective Vortex (MCV) will all combine to provide forcing for the thunderstorms. Strong moisture advection will bring high moisture content to the atmosphere. Will go high PoPs all areas at some point in this time frame.

Shear will be good with the surface low and warm front in the area, and forecast hodographs show this. Instability should be sufficient to interact with the shear to provide a threat of severe convection. There is some uncertainty in the overall strength of instability given increasing clouds, but advection behind the warm front should help overcome this some.

Additional thunderstorms may develop behind the initial line per CAMs, but this is not certain. Will keep PoPs relatively high behind the line, but then gradually lower them overnight as forcing diminishes.

The high moisture content of the atmosphere plus the threat of multiple rounds of storms will keep heavy rain and resultant flooding a threat across much of the area.

However, there remain some uncertainties that need to be mentioned. Regarding the severe threat, the MCV may enhance the surface low, which would increase the threat for tornadoes. The eventual location of the warm front is uncertain, which will impact where the higher severe threat is.

Regarding the heavy rain threat, some guidance continues to show a split of the heavy rain, north of the area (and the surface low) and down to the south of the area where more storms could rob the moisture here. Ensemble means also show the heavy rain farther north, but there are several members still showing heavy rain across central Indiana.

Thus, even though that parts of the flood watch area may not see heavy rain, given the anomalously high integrated vapor transport expected feel the threat remains high enough to continue the flood watch for all of its current area.

Highs will be dependent on how fast clouds increase, but for now expect middle 70s north to middle 80s far south. Lows tonight will be mainly in the 60s.

Monday...

An upper trough combined with some lingering forcing from the exiting surface low pressure system will keep mainly chance PoPs around during the day. However, there could be a surface trough extending west from the surface low which could increase PoPs higher than expected. Highs will be in the middle and upper 70s.

Tuesday...

Tuesday will be quiet with high pressure. Cooler than normal temperatures will persist.

Wednesday and beyond...

A weaker upper trough and cold front could bring some showers and thunderstorms Wednesday into Thursday. Will keep low PoPs going.

A stronger upper wave may bring more widespread rain again around Saturday. That far out some uncertainty still exists in the specifics, so will carry chance PoPs for now. Cooler than average temperatures will continue.

AVIATION (12Z TAF Issuance)

Issued at 632 AM EDT Sun Jun 21 2026

Impacts:

- Scattered to numerous thunderstorms around 21Z-06Z then scattered convection lingers - Outside of convection, MVFR and IFR ceilings developing mainly after 00Z Monday

Discussion:

Some brief ceilings around BKN060 are possible early at KHUF/KBMG. Otherwise, mid and high clouds will gradually give way to ceilings around BKN060 by 18-20Z.

An area of convection will likely move in from the west around 21Z then march to the east through around 04Z Monday. However, additional scattered convection will develop and persist through the night. IFR and worse are possible in convection, then overall ceilings will gradually lower into MVFR this evening and then likely IFR overnight.

A few wind gusts around 20kt may occur this afternoon late this afternoon outside of convection.

IND WATCHES/WARNINGS/ADVISORIES

Flood Watch from 2 PM EDT this afternoon through Monday morning for INZ028>030-035>037-039-043>048-051>057-060>065-067>072.