textproduct: Indianapolis

KEY MESSAGES

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

- Wind Advisory for Thursday Afternoon for Central and North Central Indiana where southerly winds may gust to 45 to 50 mph.

- Warm with highs near 80 Thursday, then a few strong to potentially severe storms during the evening. Storms may produce damaging winds and isolated tornadoes.

- Drier and cooler weather for early next week. Potentially for lows in the low to mid 30s Monday morning. Frost and freeze conditions possible.

FORECAST UPDATE

Issued at 954 PM EDT Wed Apr 1 2026

The sharp temperature gradient continues across central Indiana this evening, with readings in the upper 30s north to the middle 60s southwest. Temperatures will likely remain near steady north, fall some south central, and maybe drop a few degrees far southwest. Readings will then rise some late tonight as the warm front returns north.

Lift above the cold air continues to generate scattered showers. Isolated lightning strikes have been noted in the southern third of the area, where elevated instability remains. As the warm front moves north, coverage of showers will increase some with the additional forcing. Isolated storms may also develop north as the elevated instability moves north as well. Instability will remain low enough that severe storms are not expected.

MESOSCALE UPDATE

Issued at 821 PM EDT Wed Apr 1 2026

Colder air is making more progress than expected in the north, with temperatures in the upper 30s across the far northeastern forecast area. Meanwhile, readings remain in the 60s across the far southern forecast area, even with northeast winds. Lowered hourly and forecast low temperatures based on this.

Readings in north may dip another degree or two, while portions of the southern forecast area will fall a few degrees. Far southern areas will likely remain near steady.

KIND ACARS sounding shows a sharp inversion with the front. Above the inversion, some lift is creating light showers, so kept scattered showers in the forecast this evening. Instability remains nil or very low across much of the area, even aloft, so have removed thunder mention this evening for all but the far south where the warmer air lingers.

SHORT TERM (This evening through Thursday)

Issued at 304 PM EDT Wed Apr 1 2026

An active short term period is in the forecast with numerous rounds of showers and storms through portions of the state, windy conditions, and large temperature swings.

This Evening and Tonight...

A frontal boundary remains draped across the state today leading to numerous showers and a few storms ongoing this afternoon. The front stretches from near Sullivan to Greensburg with temperatures in the 70s to the south and upper 40s to the north.

Relatively weak elevated instability north of the boundary will put a cap on embedded thunder chances this afternoon and evening, though modest surface based instability has develop south of the front supporting thunderstorm development. While light rain showers persists along and north of the I-70 corridor this evening, focus shifts to the thunderstorms developing in South Central Indiana. Radar imagery shows thunderstorms developing right along and south of the front, along a sharp temperature and instability gradient. Effective shear of 25-30 kts, surface dew points in the 60s, and just enough skinny cape depicted on forecast soundings shows an environment conducive for multicell clusters of storms capable of producing lightning, small hail, gusty winds, and heavy rain. Better dynamics remain further south toward the Ohio River and KY; however would not be surprised to see an isolated strong to severe storm this afternoon and evening from Martin County to Jennings County. The rest of Central Indiana should escape the severe weather threat for now. Another concern with these storms will be at least a minor flood threat as flow is largely parallel to the boundary, which could produce areas of training storms.

For tonight, the area reemerges into the open warm sector with the warm front pushing rapidly northward in response to a strong surface low and upper level wave moving northeastward out of the central Plains into the upper Great Lakes. CAMs are showing the possibility of widely scattered storms overnight tonight as the boundary surges back northward as a warm front and the low level jet strengthens overhead. Forecast soundings do support the threat for elevated thunderstorms capable of producing heavy rain, lightning, and small hail. The wind threat should be fairly marginal in this set up with a strong low level inversion in place. Best chance for storms looks to be in the 10pm to 5am timeframe for Central Indiana; however confidence is lower on how widespread convection will be.

Thursday...

Thursday will again be quite windy, with PBL mixing and steep low level lapse rates likely able to mix down frequent gusts of 35-50 MPH with isolated higher gusts possible. While widespread clouds within the warm sector may inhibit boundary strong layer heating, strong warm air advection should steepen low level lapse rates enough for good mixing into the low level jet aloft. Short term models have all been in agreement with showing deep mixing Thursday afternoon leading to wind gusts over 45 mph mixing down to the surface; therefore issued a wind advisory from 11am to 7pm for portions of Central and North Central Indiana. In addition to windy conditions, expect highs approaching 80 degrees once again, with any area seeing sunshine likely warming into the lower 80s.

The shower and thunderstorm threat will ramp back up again on Thursday evening into Thursday night as one or more rounds of prefrontal convection associated with the aforementioned system move through the region. A deamplifying negatively tilted trough and associated weakening surface low pushes into the Great Lakes tomorrow. While the best forcing for ascent will be further northwest toward Chicago and the track of the overall system, enough forcing should be present across Indiana to support some convective development. Deep layer shear will remain plentiful, and low level shear will be substantial as well owing to strong low level flow and some veering in the warm advection regime. The degree of destabilization is in question giving the threat a somewhat conditional nature, but even modest instability in such a flow environment would pose at least a decent wind threat with minimal trouble mixing down 50+KT flow within a few thousand feet of the surface, as well as concern for a tornado or two. Greatest threat for severe storms will be across Northwest portions of Central Indiana, where a better instability, shear, and helicity will be present to support organized severe storms and supercells. Forecast soundings for Thursday evening show a fairly saturated column with "skinny" CAPE, generally under 1000 J/kg. Any sunshine tomorrow may significantly increase lapse rates and instability leading to a more conducive environment locally for severe weather. But overall, best dynamics will be northwest of the region. This set up still supports storms capable of producing strong to damaging winds, a few tornadoes, and flash flooding. Expect convection to develop in Illinois during the afternoon hours, then shift eastward into Indiana during the evening. Best threat for any supercells will be along the IL/IN border and in NW portions of Central Indiana before storms begin congealing into clusters and bowing segments further east. CAMs shows several rounds of storms possible extending into the Thursday night timeframe as the front stalls out over the state again.

LONG TERM (Thursday night through Wednesday)

Issued at 304 PM EDT Wed Apr 1 2026

A progressive and modestly amplified upper-level flow pattern currently exists across the CONUS. Broad troughing is found over the western US with ridging over the east. Low-level flow has largely been out of the southwest across the Mississippi and Ohio River valleys, which has lead to generally warmer-than-average temperatures over the past week. Additionally, occasionally shortwaves have been ejecting from the deeper trough over the west. These features have provided us with periodic chances for showers and storms as well.

Things change as we head into the long range, however, as the western trough begins to drift eastward. By late Sunday into early Monday, the trough axis is modeled to be over the Great Lakes. Northwesterly flow aloft returns to the Midwest, with colder air streaming southward. Ensemble guidance is in good agreement showing a trend towards cooler temperature through much of next week. Near to slightly below normal readings are favored, with daily highs in the 50s to near 60 and lows in the 30s. Multiple nights next week have the potential to be near or even below freezing. As such, the probability of frost and freeze conditions is increasing.

Days 8 - 14: Longer range ensembles hint at a return to the current pattern, featuring troughing out west with ridging to the east. A trend towards warmer-than-average temperatures and a more active storm track is favored around mid-month.

AVIATION (06Z TAF Issuance)

Issued at 205 AM EDT Thu Apr 2 2026

Impacts:

- MVFR to IFR ceilings persist through this morning

- A few showers early in the period, with showers and storms again possible late today into this evening

- Winds become southerly today sustained at 20-25KT with gusts approaching 40KT at times

Discussion:

widespread IFR ceilings are in place north of the currently stationary boundary to the south. This boundary will begin to lift northward late tonight into tomorrow, with winds shifting to the south and ceilings gradually improving as it does so. VFR conditions should return to all sites by 17-19Z.

Winds will strengthen significantly as we reemerge into the warm sector with deep PBL mixing and strong flow just off the surface. Sustained winds will reach as high as 20-25KT with gusts as high as 35-40KT at times. An isolated higher gust is possible. Gusts will remain, though drop back into the mid 20KT range this evening.

A few showers will be possible early in the period though chances will drop steadily through the morning hours before ramping back up late today. Will carry showers and VCTS where chances are highest this evening, and PROB30 elsewhere.

IND WATCHES/WARNINGS/ADVISORIES

Wind Advisory from 11 AM this morning to 7 PM EDT this evening for INZ021-028>031-035>049-051>057-060>065-067>072.