textproduct: Indianapolis

KEY MESSAGES

- Widespread minor/moderate river flooding continues south of I-70

- Locally heavy rainfall is expected late Tuesday into Wednesday, which will exacerbate or prolong ongoing flooding

- Scattered severe storms with all hazards are possible Tuesday night and Wednesday

- Well above normal temperatures expected through Wednesday

- Cooler temperatures for late this week

SHORT TERM (Today through Wednesday)

Issued at 249 AM EDT Mon Mar 9 2026

Clear skies across the Ohio Valley early this morning with a high pressure ridge centered to our southeast. S/SW winds around 10mph were keeping temperatures up with mid and upper 40s across much of the forecast area at 06Z.

The surface ridge will maintain its influence over the Ohio Valley today in particular...but a developing frontal boundary extending from the High Plains to the Great Lakes will increasingly become a focal point for convective development by late Tuesday as a surface wave kicks east into the mid Mississippi Valley. Severe storms and heavy rainfall will impact the forecast area Tuesday night and Wednesday as the cold front slowly sags across the forecast area.

Through Early Tuesday

Low pressure will track across the northern Great Lakes this morning and into western Quebec later today. As it does the pressure gradient will tighten with the surface ridge centered over the lower Appalachians resulting in breezy conditions across central Indiana for this afternoon. Peak gusts will be around 25mph before dropping off with the development of an inversion this evening.

Sunshine will be plentiful across the region for much of the day but the onset of warm advection in tandem with a plume of moisture lifting into the lower Oho Valley will support a gradual expansion of stratus into the forecast area from the southwest late today into this evening. The development of a boundary layer inversion will effectively trap moisture beneath it with stratus becoming widespread tonight. Model soundings support the potential for pockets of drizzle tonight with a broad area of dry air and subsidence present above the inversion.

Tuesday through Wednesday

A frontal boundary shifting south will align across the lower Great Lakes by Tuesday afternoon with a progressively moist airmass south of the boundary across the Ohio Valley as dewpoints surge into the 60s. Showers may develop in the vicinity of the boundary but conditions will remain benign for much of the day as a capping inversion develops over much of the region south of the boundary. The approach of a stronger surface wave in tandem with an increase in 850mb flow will help to unlock the convective development near the boundary late Tuesday with the potential for explosive organization with a supercell mode across northeast Missouri into the northern half of Illinois as the cap breaks in a highly sheared and modestly unstable environment with steep mid level lapse rates.

The cap will hold into Tuesday evening before weakening further south across central Indiana with the primary focus for severe convection remaining to the northwest of the forecast area. Storms Tuesday evening will carry a tornado risk with impressive 0-1km SRH values and hodographs showing strong curvature in the lowest 2-3km. Plenty of instability within the hail growth zone also supports the potential for large hail. Not out of the question that the supercells that develop may end up clipping the northern Wabash Valley by mid to late evening as the front shifts south but for the most part...any convective impacts will be minimal across the forecast area through the evening.

Convection will gradually grown upscale into clusters or lines as storms shift southeast into the forecast area Tuesday night. Model soundings continue to advertise ample directional shear and SRH within the boundary layer that supports a continued risk for rotating storms and tornadoes...but damaging winds are likely to become an increasing threat Tuesday night into Wednesday morning as convective mode becomes more chaotic and storms tap into 50+kt winds in the lowest 2-3km. After a brief lull...additional convective development along the eastward moving cold front is expected Wednesday afternoon focused across the southeast half of the forecast area. With weaker instability and less directional shear present...convection will primarily carry a risk for damaging winds before shifting east of the forecast area by early Wednesday evening.

While the severe weather threat is valid even with the timeframe of greatest impacts expected overnight Tuesday into Wednesday morning...the flooding concern is greater as confidence continues to grow in heavy rainfall impacting much of the forecast area. Precipitable water values will peak late Tuesday night and Wednesday morning in excess of 1.50 inches which is about 300% of the climatological normal. A broad 1 to 2 inches of rain is anticipated with pockets of higher amounts expected. This will exacerbate and potentially worsen ongoing river flooding while offering the risk for localized flash flooding due to high rainfall rates.

Temps...low level thermals support highs near 70 this afternoon. The record high at Indianapolis today is 72 from 1878 and it will be close. The potential to break a record high will come Tuesday as mid 70s abound across the forecast area. The record high for Tuesday at Indy is 74 from 2009 and the current forecast is for a high of 75. Temperatures will remain well above normal Wednesday but expect temps to begin falling in the afternoon as the front passes. Lows tonight and Tuesday night will surge into the 60s over much of the area.

LONG TERM (Wednesday Night through Sunday)

Issued at 249 AM EDT Mon Mar 9 2026

The upper level pattern across the country will transition to more of a northwest flow orientation in the wake of the midweek system with a flat ridge off the California coast. Fast moving storm systems will track through the progressive flow aloft and largely remain north of the region into the first part of the weekend. Deepening upper level energy diving out of western Canada will help to strengthen low pressure over the central Plains Sunday. The low with a trailing cold front will sweep across the region late Sunday bringing another opportunity for rainfall to wrap up the weekend. Behind this system...colder air will spread into the region for early next week as the upper level pattern becomes increasingly amplified with a ridge west and a trough east.

Lingering rain showers across southeast parts of the area will depart Wednesday evening with clearing into early Thursday as deep subsidence overspreads the Ohio Valley with a broad area of high pressure. This will bring dry and seasonable weather to the region for Thursday with warmer temperatures Friday as low level flow swings back around to southerly. A fast moving surface wave will track across the Great Lakes early Friday and may bring a few light showers to the northern half of the forecast area...otherwise dry conditions will reign into the first part of the weekend.

A warm front will extend into the region by late Saturday as low pressure begins to organize over the central Rockies. Precipitation should remain to the north of the boundary as it aligns across the lower Great Lakes. The ejection of the surface low out into the Plains then E/NE into the Great Lakes by late Sunday will bring a convective threat as the attendant cold front sweeps across the region Sunday evening. The fast moving nature of the boundary should limit heavier rainfall amounts. In the wake of this system...colder air will filter into the area with an amplified upper level ridge west-trough east developing for the first half of next week. Highs in the 60s Sunday will be followed by highs 20 to 25 degrees colder next Monday through Wednesday.

AVIATION (12Z TAF Issuance)

Issued at 535 AM EDT Mon Mar 9 2026

Impacts:

- Gusts to 20-25kt this afternoon - MVFR ceilings arriving from the southwest late today, lowering to IFR predawn Tuesday

Discussion:

Mainly clear skies will continue into the early afternoon but lower stratus currently developing in the Tennessee and lower Mississippi Valleys will advect into the region from the southwest as the afternoon progresses with MVFR ceilings encompassing the terminals by late day. Ceilings will gradually lower to near or below IFR late tonight as moisture becomes trapped beneath a sharp inversion. Cannot rule out patchy drizzle late tonight as well.

Southwest winds will persist through much of the day...increasing this afternoon as the pressure gradient gradually tightens. Peak gusts at 20 to 25kts are possible this afternoon before dropping back to 10 to 15kts this evening.

IND WATCHES/WARNINGS/ADVISORIES

None.