textproduct: Indianapolis

KEY MESSAGES

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

- Flooding threat for both river/non-river will increase through the early week from heavy rainfall on damp/saturated soils

- Temperatures will trend from slightly below normal to near normal through Saturday...trend to very warm/humid late in period

DISCUSSION (This evening through Sunday)

Issued at 302 PM EDT Sun Jun 21 2026

This afternoon through Monday...

Quiet weather conditions continue across central Indiana at this time ahead of an approaching MCS with an associated MCV. Look for this system to continue pushing eastward supporting widespread showers and thunderstorms towards this evening. Increasing clouds has limited destabilization to some degree, but moisture advection and daytime heating is allowing for gradual destabilization this afternoon. Deep-layer and low-level shear will also increase over the next several hours with the approaching disturbance promoting stronger flow. Favorable effective shear values around 30-50 kt combined with modest instability supports the potential for organized storms with all hazards possible.

Latest model guidance still depicts enlarging low-level hodographs across portions of central IN favoring an isolated tornado threat. The greatest tornado threat is across southwest portions of central Indiana where the greatest instability and low-level wind shear overlap. Some uncertainty remains on storm mode at least initially. There does appear to be at least a brief opportunity for discrete cells later this afternoon into the early evening before multiple linear segments then develop leading to a greater damaging wind gust threat with embedded tornadoes possible. Isolated large hail cannot be ruled out, but modest instability and linear storm mode by the evening hours should mostly limit this threat.

A Flood Watch is in effect through 8 AM Monday morning for much of central IN with the potential for 1 to 3 inches of rainfall from multiple rounds of storms. Locally higher amounts cannot be ruled out. Expect precipitation chances to diminish late tonight into Monday morning as the aforementioned disturbance shifts east. Surface high pressure will then build in providing quiet weather for much of the day Monday. Isolated showers are possible across east- central IN through the first half of the day. Lingering clouds and northerly surface flow will keep temperatures cooler. Look for highs in the 70s.

Monday night through Sunday...

Generally active pattern will continue this week amid overall zonal pattern. Established trough over northern North America that has been guiding mid-latitude pattern...will shift from south-central Canada to more pronounced, perhaps cut-off upper lows over SW Canada to the northern Rockies late this week. This transition will allow a subtropical ridge to build over the central US, bringing seasonably warm and humid conditions into Indiana next weekend.

The next round of broad and seasonably weak Canadian surface high pressure will pass through Indiana Monday night to Tuesday night, dropping dewpoints to the mainly low to mid-50s at night, and light northerly breezes under H850 temperatures as low as 10 degrees Celsius during the day Tuesday. Transition back to more summery weather Wednesday with light southwest flow returning moderate humidity ahead of next wave...which should bring periods of scattered RWs/few TRWs through the Wednesday night-Thursday night period as the disturbance's boundary slowly crosses the region.

Expect a shorter period of improvement around the Friday timeframe as western trough deepens near Vancouver...only allowing next northern surface ridge to graze the CWA, with isolated diurnal convective chances continuing...and increasing through Saturday as light southerly flow boosts humidity through moderate to high levels. Temperatures through the workweek to see subtle increase in afternoon maximums from around 80F to low 80s, although mid-80s should be more common along the US-50 corridor...while morning lows steadily climb from 50s to 65-70F by week's end.

AVIATION (18Z TAF Issuance)

Issued at 140 PM EDT Sun Jun 21 2026

Impacts:

- Scattered to numerous TSRA around 21Z-06Z...sct convection after - Outside of convection...CIGs to deteriorate from west to east, to MVFR 23Z-02Z...and to IFR, NW to SE, during 03Z-08Z - Winds veering to southerly by 04Z south of KLAF...and NNW by 18Z Monday

Discussion:

VFR conditions will continue near central Indiana terminals through 22Z at KLAF...and 23Z-02Z along/south of I-70. Surface low pressure, currently over northern Missouri, will slowly cross the region through the TAF period. Mid/high clouds will gradually give way to lower CIGs around 050-060 by 20Z-21Z. Associated area of convection currently over most of Illinois will reach KLAF/KHUF around 21Z...and KIND/KBMG by 23Z...continuing into the late evening. Expect further scattered -SHRA/convection through at least 12Z Monday. Winds to gust to 15-20KT at times through the period outside of convection...with flow veering with the passing surface low, from southeasterly this afternoon and early evening, to southerly by 04Z at sites south of KLAF.

IND WATCHES/WARNINGS/ADVISORIES

Flood Watch through Monday morning for INZ028>030-035>037-039- 043>048-051>057-060>065-067>072.