textproduct: Indianapolis

KEY MESSAGES

- Potential for showers/storms early this morning, better chances in the afternoon and evening

- Dry and quiet this weekend

- Strong to severe storms likely Monday into Monday night

DISCUSSION (Today through Thursday)

Issued at 302 AM EDT Fri Apr 24 2026

A cold front is approaching Indiana from the west, and extends from Iowa southward through Missouri as of 2am. Extensive shower and thunderstorm activity is occurring along the entirety of the front. This activity has been gradually weakening as it outruns its source of lift and encounters a more stable air mass. Additionally, available wind shear greatly diminishes with eastward extent, allowing ongoing storms to quickly become cold pool dominant. CAM guidance is in good agreement showing these storms diminishing as the reach Indiana, with some showing complete dissipation.

The majority of guidance shows at least some isolated to scattered shower activity arriving as early as 12z. We will include chance PoPs through the morning hours to account for this. Shower and storm chances then increase during the afternoon hours as daytime heating allows for some modest destabilization (MLCAPE 500-1000 J/Kg). Wind shear is modest as well, roughly 20-30kt through the depth of the column. From a storm-relative standpoint, however, shear is almost non-existent. As such, storms today should display mostly single cell to multicell characteristics.

Taking a look at hazard potential, the overall threat seems low. Model soundings show some dry air in the lower levels, which may allow for a brief downburst within stronger cells. Additionally, should storms congeal into a cluster than cold pool dynamics could allow for a brief surge capable of damaging winds.

Aside from storm activity, increasing clouds and precipitation should keep temperatures fairly muted compared to yesterday. Highs in the 70s will be common. The aforementioned cold front arrives just after midnight Saturday, with clearing skies and a wind shift to northerly. Cooler air gradually filters in, with high temps remaining in the low to mid 70s for the next several days. Expect nightly low temperatures in the upper 40s (north) to mid 50s (south) through the weekend.

MONDAY SEVERE WEATHER POTENTIAL

Attention then shifts to the significant synoptic event unfolding for Monday. Recent global model guidance, including the GFS and ECMWF, has shown remarkable consistency in depicting a vigorous, negatively-tilted mid-level wave ejections out of the Southwest. This feature is expected to induce rapid surface cyclogenesis over the Central Plains by Sunday night, with the resulting sub-995mb surface low tracking toward the Upper Mississippi Valley by Monday afternoon. This will result in a significant northward surge of Gulf moisture, with dewpoints expected to reach the mid 60s as far north as the I-70 corridor.

Scientifically, the Monday setup is particularly concerning due to the coupling of strong kinematics and significant instability. Guidance indicates a 55-65 kt LLJ will be in place across central Indiana by Monday afternoon, which will not only provide intense low- level moisture transport but also contribute to enlarged, curved low- level hodographs. 0-1 km SRH values exceeding 250 m2/s2 are currently being modeled, which would be more than sufficient for a tornado threat if storms can remain discrete. CAPE values in the 2000-3000 J/kg range appear plausible given the WAA regime. While some global models show a faster progression with a QLCS along the cold front, the potential for pre-frontal supercells within the open warm sector cannot be ruled out, especially given the degree of forcing from the approaching shortwave.

Furthermore, the high PWAT values approaching 1.5 to 1.7 inches, which is near the 90th percentile for late April, will introduce a risk for flash flooding. The orientation of the LLJ relative to the advancing front suggests the possibility of training cells or back- building convection during the Monday night period. As the primary surface low moves into the Great Lakes by Tuesday, a powerful cold front will sweep through the Ohio Valley, effectively shunting the moisture south and ushering in a much cooler, drier airmass for the middle of next week. In the wake of this system, GEFS and EPS means show a period of high-pressure dominance with temperatures returning to near or slightly below seasonal norms.

AVIATION (12Z TAF Issuance)

Issued at 639 AM EDT Fri Apr 24 2026

Impacts:

- Wind gusts around 20-25 kt this afternoon - Showers and possibly a thunderstorm today - Wind shift to northerly as cold front passes tonight

Discussion:

A cold front is approaching from the west and will arrive late in the TAF period. Shower and thunderstorm activity is associated with the front, which extends from northern Illinois south through Missouri. Over Indiana, only thin high cirrus has been observed as of this writing. Clouds are expected to increase, thicken, and lower with time as the front approaches.

Showers and storms along the front should gradually weaken, but not completely dissipate, as they reach Indiana by 15z. As such, we will include a VCSH group in the TAFs to start before introducing a PROB30 for thunderstorms in the afternoon. Most guidance shows thunderstorm activity redeveloping during the afternoon, especially from IND to BMG eastward.

Ceilings remain VFR for most of the day, gradually lowering during the afternoon as shower/storm activity increases. Stratocumulus may persist into the night with gradual clearing by the end of the TAF period.

Winds remain out of the south through this morning, before becoming southwesterly during the day. Gusts may top 20-25kt at times. Winds diminish and become westerly as the front passes through. Afterward, roughly around 04z-06z, winds become northerly and increase slightly as the cooler air mass behind the front arrives. Mainly clear skies and northerly winds around 10kt persist through Saturday.

IND WATCHES/WARNINGS/ADVISORIES

None.