textproduct: Indianapolis

KEY MESSAGES

- Wind gusts of 30 to 40 MPH at times this afternoon and Thursday.

- Wet pattern through the week and into the weekend, with multiple rounds of showers and storms expected, which may produce renewed flooding along area waterways

- A few strong to severe storms and locally heavy rainfall are possible mainly northern portions of central Indiana tonight.

- Potential for additional heavy rainfall and severe weather for late Thursday and again late Saturday.

- Drier and cooler weather for early next week.

SHORT TERM (This evening through Wednesday)

Issued at 329 PM EDT Tue Mar 31 2026

Rest of this afternoon...

Subtle shortwave trough will continue to push east through the lower Great Lakes. Ample elevated instability (MUCAPE around 1000 j/kg) and limited instability will support a threat for scattered thunderstorms with small hail, gusty winds up to 45 mph and locally heavy rain for the next 1-3 hrs before weakening and ending from the west by 22Z.

Tonight...

Thunderstorms have begun to develop along a line from the western Chicago Suburbs back towards the Quad Cities. This activity is forming in a region of deep moisture convergence ahead of the main frontal boundary. Expected storm motions and current location agree with bulk of CAM guidance which moves this activity into far NW portions of central Indiana around 00Z. Similar to this mornings activity, threat will initially be large hail thanks to steep mid level lapse rates up to 7.5 C/KM. Elevated TS activity that moved through NW portions of the forecast area in the last 1-2 hrs has stabilized the BL. However, sufficient heating should redevelop before 00Z that near surface based parcels will support an additional threat for damaging winds. Activity will also be working with around 1.3 inch PWAT, which combined with slow storm motions will lead to threat for locally heavy rainfall. The threat for severe down to I-70 per recent SPC day 1 outlooks seems a little too far south given the slow storm motions and increasing cinh with southward extent. However the WPC day 1 marginal location looks reasonable. As the cold front accelerates southward later tonight, aided by CAA of Lk. Michigan, expect the greatest the for heavy rain to gradually shift south towards I-70 by 12Z Wednesday.

Wednesday...

Given strong convective overturning and weakening mid level lapse rates owing to building heights and latent heat processes, thunderstorm activity will continue to weaken and diminish in coverage during the morning. However, strong deep convectively enhanced frontal convergence aided by 30-40 kt 850mb jet will support the threat for multiple rounds of heavy showers along the frontal boundary during the day. Uncertainty exists on the exact QPF amounts, so decided to not hoist a Flood Watch, but over 1 inch of QPF is possible between 12-00Z. Expecting the frontal boundary to push much further south than NBM guidance and thus have undercut highs by 1-2 categories, remaining in the 40s/50s along and north of I-70.

Wednesday night...

Frontal boundary will lift northward as a warm front as strong pressure falls develop associated with another shortwave trough digging southward through the rockies and surface low pressure intensifying over the high plains. Showers and isolated TS chances will end quickly from the south early in the period as the front moves north of the CWA by 06Z. In fact Wednesday's high temps for most areas north of I-70 will occur just before 04Z.

Thursday and Thursday night...

As the next shortwave kicks eastward into the plains into the western Great Lakes, an associated frontal zone will push eastward to near the upper MS river by Thursday afternoon. Early morning TS over the Ozarks may move far enough east to aid in a convective outflow boundary ahead of the primary frontal forcing to support renewed convection along this boundary by afternoon just west of central IN. With little to no mid level height falls, soundings indicate substantial inversion centered around 500 mb robbing a deeper CAPE profile. Thus the slight risk has a lot of conditional nature to it, with many negatives limiting the threat at the moment. NBM Pops were lowered some, but possibly not enough given the limited deep forcing and marginal instability.

LONG TERM (Wednesday night through Tuesday)

Issued at 329 PM EDT Tue Mar 31 2026

Unseasonably warm and anomalously humid pattern to continue into the late week amid continued chances of rain/thunder..before mid-weekend transition to dry and much cooler conditions early next week. Indiana's position, Friday and into Saturday, in the subtropical warm sector south of a rather quick zonal mid-level flow near the CONUS-Canada border...will provide a quasi-continuous ribbon of anomalously high precipitable water off the Gulf, separated by perhaps a shorter period of drier mid-levels between passing. rounds of forcing. Steady S/SSW surface flow will hold 55-65F dewpoints over the CWA, promoting high-POPs of low-QPF around the Friday timeframe. Overall breezy conditions will likely include one more windy day Thursday where gusts to at least 25-35 mph will be possible.

Final period of steadier rainfall is expected to precede a regime- changing cold front expected to cross Indiana around the late Saturday-Saturday night timeframe. Widespread moderate rainfall and isolated to scattered thunder would be the most likely solution, with potential for an additional 1.00-2.00 inches of rainfall under heavier downpours/storms...as the boundary takes a slower passage across the region. This final round of rain may be the one to take a few local creeks and river points from Action Stage into Minor Flooding, or at least prolong ponding of low-lying areas into early next week.

A distinct transition to below normal temperatures will follow into Sunday, with rain-free conditions and dewpoints falling to around 30F as seasonably strong surface high pressure builds into the Great Lakes/Midwest into Monday. Current NBM timing would only allow maximums 10 degrees below normal Sunday...with subsequent clearing and diminishing winds promoting frost late Sunday night. Any moderation into the mid-week to be modest and towards near normal conditions. The normal max/min at Indianapolis through the long term is 60/40.

AVIATION (18Z TAF Issuance)

Issued at 148 PM EDT Tue Mar 31 2026

Impacts:

- Thunderstorms in vicinity of all terminals except BMG this afternoon with coverage increasing between 00-06Z.

- Southwest winds gusting 30-37KT during the afternoon

- Wind shift to North with MVFR conditions in light rain developing at KIND after 09Z.

Discussion:

Scattered thunderstorms have been persistent over eastern portions of IL and have moved into far western parts of IN the last hour. This activity will move east and be in the vicinity of KHUF, KIND and KIND through the 20-21Z period. Gusty SW winds from 30-37 kts will continue this afternoon before diminishing around 00Z.

Additional TS activity is expected to form across northern portions of Indiana along a cold front between 21-23Z. This activity will push gradually SE and affect all terminals except KBMG between 00- 06Z with occasional MVFR visibility in the heavier showers. A cold front will push south and move through KIND after 09Z with MVFR ceilings expected.

IND WATCHES/WARNINGS/ADVISORIES

None.