textproduct: Indianapolis

KEY MESSAGES

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

- Strong to severe storms possible mainly Saturday; damaging winds and hail will be the primary concerns

- Drier and cooler weather Sunday through early next week. Potential for lows in the low to mid 30s Monday through Wednesday mornings. Frost or freeze conditions possible.

FORECAST UPDATE

Issued at 1000 PM EDT Fri Apr 3 2026

Some weak lift is generating scattered convection across areas from Indianapolis east and southeast this evening. Convection is behaving itself. MLCAPE values are around 1000 J/kg but shear isn't great. The storms are pulsing up and down as they move northeast. Wouldn't rule out some small hail or gusty winds, but the overall severe threat seems low.

Meanwhile, across the far northern forecast area, the airmass was modified by earlier convection. Canceled the Tornado Watch earlier due to these conditions limiting any severe threat. Some instability remains aloft, and isolated showers have been developing in this area.

Increasing 850mb flow will help keep some scattered convection around into the early overnight. Will keep some PoPs going, but will have them no higher than chance category. There will be a lull in rain coverage for the mid and latter parts of the overnight, so will mainly have some low PoPs across the far north (closer to the warm front) and across the west (closer to the approaching cold front).

Closer to 12Z, forcing from the cold front will allow some rain to enter the far western forecast area, so kept high PoPs there at that time.

Again, the severe threat is low, but nonzero. Gusty winds and small hail will be the main threats along with locally heavy rainfall.

MESOSCALE UPDATE

Issued at 630 PM EDT Fri Apr 3 2026

Early evening convection has developed across Central and Northcentral Indiana, mainly associated with a couple notable boundaries. All boundaries are found easily from the satellite imagery, with a weaker less potent boundary displaced to the southeast of the Indy Metro. The other is along the northern suburbs of the Indy Metro, then the more active boundary along the northern periphery of the forecast area from Warren/Fountain counties stretching east through Tippecanoe into Carroll county. This boundary is slowly drifting north, but along and just north there is considerable upscale growth to the convective elements. Unfortunately the boundary is equally adding some enhance helicity and allowing a few updrafts to demonstrate some rotation based off of latest radar imagery.

The environmental features are demonstrating around MUCAPE of 1000J/Kg within that northern boundary, further south MUCAPE is marginally less but still worth a mention. Along the northern half of the forecast area a layer of stronger wind shear is also found within the 0-6km layer roughly in the 35-45kt range. This would suggest that the continued development or sustaining the current/ongoing convection will occur. But as convection lifts north towards White County the environment is more favorable which is along the stronger gradient of dynamics in the lowest 3km of the atmosphere. Lapse rates are the one element keeping the atmosphere under some control around 6-6.5 deg C/km which should help to limit some stronger development and coverage for convection this evening across Central Indiana.

SHORT TERM (This evening through Saturday)

Issued at 302 PM EDT Fri Apr 3 2026

A warm front is lifting north across Indiana this afternoon, and stretches roughly from Champaign IL through Lafayette eastward through Kokomo then into Ohio. Satellite imagery reveals the front well, with a rough unstable cumulus field south of it and a stable wave-like stratus layer to the north. As the front lifts northward this afternoon, enough instability should develop for showers and thunderstorms.

THIS AFTERNOON

ACARS soundings out of IND confirm this with increasing instability, around 1200 J/Kg MUCAPE as of 2pm. Concurrently, radar imagery has started to show a few weak echoes around this time. We are likely beginning to reach convective temperatures which are in the mid 70s. As temperatures gradually increase, convection should become more widespread and gain intensity.

Convective coverage will be limited by relatively weak synoptic lift. Our primary lifting mechanisms are confined to buoyant forces and isentropic lifting from the front itself. This should help keep activity fairly discrete this afternoon. Effective shear is fairly modest, between 20-30 knots. However, this may be enough to allow for some storm-scale organization. A few multicell clusters or even an isolated supercell is possible.

Model soundings show modest lapse rates between 6-7 C/Km today, with a very moist profile up through the EL at 10-12 Km. Hodographs have some curvature within the lowest 3km, but not a whole lot. Still, enough is present to allow for an isolated mesocyclone as mentioned above. This could allow for a large hail, wind, and isolated tornado threat. The overall chances are low, but greatest near the front itself which will quickly lift northward out of our CWA this afternoon and evening.

SATURDAY

Further west, surface low pressure is expected to develop over Iowa this afternoon and move northeastward overnight. Thunderstorms are expected to develop along the system's cold front which extends north to south from Kansas down into Oklahoma. Convection is modeled to congeal into a line, progress eastward, and enter Indiana around 10-12z Saturday morning. Most if not all guidance show it in a weakening state as it arrives. Overall, severe potential seems low due to limited instability. However, a potent low-level jet may allow for sporadic wind gusts with any of the stronger convective cores. This potential increases through the day as the line heads eastward, and may pose a more organized severe weather threat by the time it reaches Ohio.

Temperatures remain warm through the night tonight within southerly flow. Readings overnight may not drop out of the 60s. However, as the cold front arrives an abrupt wind shift is expected with rapidly falling temperatures. Readings may drop from the 60s/near 70 quickly into the 50s during the afternoon hours. By Saturday night, lows in the 30s are expected. Frost is possible by Sunday morning, but breezy conditions may limit this somewhat.

LONG TERM (Saturday night through Friday)

Issued at 302 PM EDT Fri Apr 3 2026

A few day period of dry, yet colder conditions expected Sunday through the first half of next week before temperatures warm back toward and above seasonal norms.

Broad troughing moves in over the Great Lakes region on Sunday with Indiana being under the influence of northwesterly flow aloft. Surface high pressure becomes centered over the Plain while an area of low pressure races northeast into Quebec resulting in a much colder airmass advecting in from the northwest. This pattern sets the stage for a few day period of below normal temperatures with the threat for frost/freeze conditions by next week.

On Sunday, much drier and colder air is advected in by strong northwesterly flow. Aloft, the upper level trough axis pushes in overhead, potentially sparking off an afternoon shower. The threat for this is low; however forecast soundings and BUFKIT profiles show an environment conducive for widespread afternoon cumulus. There may be enough moisture for an isolated shower to develop during the early afternoon as the trough axis pushes through, but overall expect a dry day. Steep low level lapse rates from cold air advection aloft will allow for stronger wind gusts of 20-25 mph to mix down to the surface through the day, making it feel even colder. Temperatures Sunday morning bottom out around 40 and struggle to rise into the lower 50s.

A weak wave and surface boundary within the northwest flow move into the Great Lakes region late Sunday night. With limited moisture associated with this, the only sensible impacts for Central Indiana will be elevated winds around 5-10 mph overnight Sunday into Monday morning then gusts to 20-25 mph again Monday afternoon. These winds may help prevent frost/freezing conditions during the morning hours despite the cold airmass in place. Keeping forecast lows in the upper 30s for Central Indiana; thinking patchy frost could be possible in South Central Indiana where winds may be weaker allowing for better radiational cooling. Highs rebound into the mid 50s to near 60s by Monday afternoon.

Another Canadian high pressure system becomes centered over the Great Lakes by Tuesday afternoon bringing a reinforcing shot of colder air to the region. With the high center nearby Tuesday morning, winds may drop off enough to allow for better radiational cooling, especially for North Central and northwestern portions of Indiana. Best chance for lows near or below freezing will be along and north of I-70. Lower confidence if winds will diminish enough to allow for frost formation as the center of the high will be over Wisconsin early Tuesday. Despite slightly elevated winds, Tuesday morning looks like the best set up for potential frost or freezing conditions.

Later into the work week, strong low pressure traverses the US/Canadian border while high pressure shifts east, placing Indiana once again in a much warmer southerly flow pattern. An extensive, elongated frontal boundary extends west/southwestward from this low back to the central Plains and stalls out somewhere in or just north of the region. This will reintroduce chances for showers, and perhaps a few storms Thursday or Friday. Great forecast uncertainty exists toward the end of next week regarding the exact evolution of the set up and placement of synoptic features. Confidence is increasing through in a much warmer and potentially wetter pattern setting back up the latter half of next week and into the following weekend.

AVIATION (00Z TAF Issuance)

Issued at 800 PM EDT Fri Apr 3 2026

Impacts:

- Occasional gusts to 25kt mainly after 9Z Sat. - Widespread showers and embedded thunderstorms Saturday morning into afternoon.

Discussion:

Winds should range from 10-15kt with gusts between 20-25kt at times. Speeds decrease a bit overnight to around 10kt while becoming more southerly. A return to southwesterly is anticipated Saturday morning. Winds continue from the southwest until a cold front arrives late Saturday afternoon with a wind shift to westerly.

Most guidance shows showers and thunderstorms this afternoon along the warm front. However, this activity will be scattered in nature. Timing these showers/storms for any particular terminal will be tricky, so a Tempo group was added to cover the most probable time frame.

A stronger line of storms associated with the cold front arrives Saturday morning. Rain is likely, with embedded thunderstorms. A prob30 was included for thunderstorms with reductions in visibility.

IND WATCHES/WARNINGS/ADVISORIES

None.