textproduct: Indianapolis

KEY MESSAGES

- Scattered showers/t-storms this evening and especially Monday, with greater coverage in afternoon...isolated flooding possible

- Humid and very warm this week...daily rain chances continue through Friday...readings near 90F on Thursday

- Slightly cooler weather for the weekend with lower rain chances

FORECAST UPDATE

Issued at 949 PM EDT Sun Jun 7 2026

Diurnal cooling in combination with diabatic cooling along and north of I-74 has removed much of the surface based instabilty across central Indiana, with only light stratiform rain still remaining over NE portions of the state. Any ongoing light rain should dissipate over the next few hours. There is an outside chance at a very isolated shower or thunderstorm if one can root itself above the PBL as a weak elevated front moves northward, otherwise, dry weather expected from 11PM through 5AM tonight.

Another round of showers and storms is expected to arrive along modest isentropic lift tomorrow morning. Generally this rain should not be impactful, but given highly saturated gounds NE of I-74, isolated areal flooding cannot be ruled out. The more problamtic rainfall is expected to be tomorrow afternoon as additional diurnal thunderstorms will be possible from 1PM onwards. These thunderstorms will once again be effecient rain producers, but there should be enough steering flow to limit the potential for localized flooding to areas with highly saturated soils.

MESOSCALE UPDATE

Issued at 607 PM EDT Sun Jun 7 2026

Surface and radar analysis shows a composite outflow boundary extending roughly along the I-74 corridor from southern Rush county all the way back into Warren and Fountain counties. ACARs sounding from KIND show around 1.9 inches of PWAT. Multiple storm scale boundary interactions, diabatic processes and meso-beta scale low pressure area circulations enhancing mass convergence will continue to support a heavy rain/flooding threat. Recent CREST streamflow data suggests that localized areas of flash flooding may develop in the 1-2 hrs across NE portions of the Indy Metro area, namely in the vicinity of Castleton and Lawrence.

Additional attention is also being focused along the outflow boundary in Warren, Fountain and Tippecanoe counties. These areas received between 4 and 7 inches of rain and any additional significant rainfall from developing convection may support a quick transition to flash flooding. This area remains in WPC's Day 1 slight risk for flash flooding.

In addition to the flash flooding threat, sufficient strong low level vorticity and 0-3 KM CAPE from 125-150 J/KG over northeastern portions of central Indiana favor some potential for brief landspout/non-supercell tornado through 9 PM.

Expectation is with loss of daytime heating, convection will quickly diminish. However localized areas of longevity may continue until 02- 03Z (10-11 PM) if diabatic processes can overcome the decreasing larger scale instability diminishment.

DISCUSSION (This evening through Sunday)

Issued at 428 PM EDT Sun Jun 7 2026

Surface analysis this afternoon shows a frontal boundary across northern Central Indiana, stretching into Central Ohio. This boundary was caught between high pressure over the Great Lakes and another high over the southeastern states. Warm and humid southerly flow was in place across the majority of Central Indiana. Dew point temperatures were in the upper 60s to lower 70s. Aloft, an upper trough was found over the Central Plains states, slowly pushing northeast. Water vapor shows a plume of tropical moisture ahead of the trough flowing into the Mississippi and Ohio River valleys, providing deeper moisture within the column. Radar shows some shower development associated with upper moisture developing across Indiana. GOES19 shows CU development across Central Indiana.

HRRR this afternoon continues to suggest light shower development through the afternoon, associated with the NW-SE upper level moisture band surging northward. SPC mesoanalysis suggests CAPE over 2000 J/KG in place across our forecast area. THus continue sct rain shower development will continue to be expected, particularly along and north of I-74.

As heating is lost this evening, showers are expected to diminish, leading to a mostly cloudy night. GOES19 shows plentiful cloud cover ahead of the trough pushing northward into Central Indiana within the tropical plume. This is expected to be with us overnight. Dew points near 70 will only allow lows to fall to around 70 overnight, resulting in a warm and humid night.

Monday and Monday Night...

The upper trough axis to the west is expected to approach Indiana tonight and arrive over Indiana on Monday. Ample forcing within the flow aloft will help to drive precipitation, as plentiful moisture will be win place with surface high surface dew points and a tropical plume aloft. Forecast soundings show a saturated column by Monday afternoon with high pwats over 1.8 inches. Heavy rain will be possible that could result in flooding, especially in areas like Covington and Attica which received several inches yesterday. HRRR is also on board for the moment, spreading scattered showers and storms across Indiana. Thus will use high pops. Clouds and rain may hamper high temperatures as we may only reach around 80.

Rain is expected to continue to on Monday evening before diminishing overnight. The upper trough axis is expected to push into Ohio on Monday night. This results in the arrival of subsidence as seen within forecast soundings as top down drying comes into play.

Tuesday...

The upper trough will still be in place over Ohio on Tuesday and models continue to suggest some lingering lower level moisture during the morning hours. This could lead to some very light rain showers as through the morning, particularly across the eastern parts of the forecast area. Much better clearing is expected to arrive by afternoon as the trough axis exits farther east. Forecast soundings at that time suggest a dry column on Tuesday afternoon, but warm temperatures in the upper 80s.

Tuesday Night...

There is low confidence for precipitation on Tuesday Night at the moment. Models are showing sufficient low and mid level saturation overnight as a poorly defined upper wave passes, amid what should be ridging building in the wake of the departed trough. The lower levels appear unorganized also, just depicting warm and humid southerly flow in place. Thus will continue to keep some mention of pops in the forecast due to model trends, but confidence is low.

Wednesday...

More warm and humid SW flow will be in place on Wednesday with little in the way of forcing available other than diurnal heating. Forecast sounding suggest typical afternoon and evening instability showers will be possible given the warm and humid air mass. Will include pops for now. Low confidence.

Thursday and Friday.

The commencement of the long-term period on Thursday and Friday features central Indiana deeply embedded within a progressive, moisture-rich warm sector. Recent global deterministic runs of the GFS and ECMWF, along with support from the GEFS and EPS ensemble means, show a consensus that a stagnant subtropical ridge off the Carolinas will keep the local area under a regime of steady low- level warm air advection and moisture convergence. Boundary layer moisture will be robust for mid-June, with surface dewpoints progged to consistently reach into the upper 60s and lower 70s. Strong diabatic heating operating on this high theta-e airmass will lift afternoon maximum temperatures into the upper 80s and lower 90s on Thursday, yielding highly unstable atmospheric profiles. Soundings show MLCAPE values exceeding 2000 to 2500 J/kg during peak afternoon heating. While mid-level lapse rates remain somewhat modest, the lack of significant convective inhibition means that isolated to scattered pulse-type thunderstorms will easily trigger along any remnant mesoscale outflow boundaries.

A more organized severe weather and heavy rainfall threat materializes by late Thursday into early Friday as a deeper mid- level trough pivots out of the Upper Midwest and pushes a cold front toward central Indiana. This synoptic feature will provide the necessary large-scale dynamic ascent and wind shear to organize the highly unstable environment. Forecast models indicate 0-6 km bulk shear vectors increasing to 35 to 45 knots, shifting the convective mode from unorganized pulse cells into a forward-propagating linear structure or robust multi-cell clusters. Damaging straight-line winds and isolated large hail will be the primary hazards with any severe cores ahead of the front. Furthermore, precipitable water values are projected to climb toward 1.75 to 2.00 inches, which sits well above the 90th percentile for early June. These high moisture profiles indicate extreme precipitation efficiency, and any training convective elements ahead of the slow-moving boundary will pose a localized flash flooding threat, particularly across areas with saturated antecedent soils.

Saturday and Sunday.

A pattern shift then takes place late Friday night into Saturday morning as the surface cold front clears the southern counties of Indiana. Strong anticyclonic building will commence as a sprawling 1024 mb Canadian high pressure system drops southward across the Great Lakes. Robust cold air advection will take hold through Saturday morning, driven by a sharp northwesterly wind shift. Deep- layer subsidence and dry air entrainment will rapidly clear out the tropical moisture plume, forcing precipitable water values down to under 0.75 inches by Saturday afternoon. There are some signs of another system towards Sunday with the Canadian model and its ensembles showing a mesoscale driven system, but confidence is very low at this time, especially considering how far it lies from the other global models.

AVIATION (00Z TAF Issuance)

Issued at 746 PM EDT Sun Jun 7 2026

Impacts:

- VFR tonight; showers diminishing near KLAF and KIND - MVFR Cigs expected on Monday with scattered showers and thunderstorms late morning through afternoon.

Discussion:

Shower and thunderstorm activity will continue to weaken across northern portions of central Indiana the remainder of the evening. Have removed VCTS from both KIND and KLAF terminals as only lingering showers are expected next few hours.

VFR conditions are expected at all terminals overnight, before MVFR ceilings develop around 12Z ahead of approaching system moving NE out of the Ozarks. With this system, scattered showers will move into all terminals during the late morning. Peak in diurnal heating is expected to support greater instability with scattered thunderstorms developing after 16Z lasting until late afternoon. Have covered this with VCTS and TEMPO -TSRA for all terminals during this period.

IND WATCHES/WARNINGS/ADVISORIES

None.