textproduct: Indianapolis

KEY MESSAGES

- Slightly elevated fire danger today with wind gusts to 30 mph and RH as low as 30 percent

- Numerous rain showers with a few thunderstorms Friday

- Rain returns early next week with the potential for strong to severe storms and renewed flooding

DISCUSSION (This evening through Thursday)

Issued at 216 PM EDT Thu Apr 9 2026

Through Tonight.

The primary focus for the rest of today remains the unseasonably warm temperatures and slightly elevated fire danger. With central Indiana situated in the warm sector of a low pressure system over the Great Lakes, strong WAA is occurring. Deep mixing of the boundary layer is expected to tap into 25-30 kt winds at the top of the layer, resulting in surface gusts near 30 mph this afternoon. These mixing processes, combined with a persistent dry layer sampled in recent soundings, will likely drop afternoon relative humidity values to near 30 percent. When combined with the breezy conditions and temperatures reaching the mid-70s, roughly 15 degrees above the norms slightly elevated fire danger persists. Cloud cover will increase late tonight as the cold front nears the Wabash Valley, but precipitation is expected to hold off until the predawn hours for the northwestern counties.

Friday Through Saturday.

The cold front is progged to gradually sag southeastward across the forecast area on Friday. Guidance suggests that the primary upper level forcing will become increasingly detached from the surface boundary as the parent low moves further into Canada. Consequently, while widespread rain showers are expected, the lack of robust deep- layer shear and marginal instability, generally under 500 J/kg of CAPE, will limit the convective threat. An isolated thunderstorm cannot be ruled out, particularly for areas south of the I-70 corridor where slightly better moisture return may overlap with the frontal passage, but severe weather is not anticipated. Total rainfall amounts should remain manageable, generally under half an inch. Frontal passage will occur by Friday evening, ushering in a slightly cooler but still mild airmass for Saturday with highs ranging from the mid-60s to low 70s.

Sunday Through Thursday.

The long-term period features a highly amplitude pattern shift that warrants close monitoring for severe weather potential. Sunday serves as a transition day as surface high pressure slides east and intense southwesterly flow resumes. Ensembles, including the GEFS and EPS, are in strong agreement regarding a rapid surge in 850mb temperatures, which should propel surface highs into the low 80s by Sunday afternoon. This ridge-building phase will be short-lived as a potent western CONUS trough begins its eastward ejection. By Monday and Tuesday, a broad theta-e ridge will establish itself over the Midwest, characterized by dewpoints climbing into the 60s. The deepening surface low will then move toward the Upper Mississippi Valley, resulting in the strengthening of the low-level jet (LLJ) and steepening mid-level lapse rates which will create a classic spring setup for organized convection. While deterministic models still show timing discrepancies regarding individual shortwaves, the ensemble mean suggests a significant severe weather window centering on Tuesday and Wednesday. Given the projected kinematic profiles and degree of instability, all modes of severe weather may be possible across central Indiana during this timeframe.

AVIATION (18Z TAF Issuance)

Issued at 216 PM EDT Thu Apr 9 2026

Impacts:

- VFR conditions through at least 101300Z

- MVFR conditions spreading across Central Indiana toward 101800Z

Discussion:

A stalled, elongated frontal boundary will remain across northern Indiana and northern IL this evening and through much of the overnight. This will keep the TAF sites within the warm sector with south to southwest flow across central Indiana. GOES16 shows little in the way of cloud cover across the Taf sites and the region. Forecast soundings through the evening and into the overnight show a dry column.

On Friday, the elongated, weak front will sag southward into Central Indiana. This will bring a change in wind direction during the late morning and early afternoon. MVFR clouds will arrive with the front along with chances for some scattered light showers. Here, forecast soundings suggest a nearly saturated column by mid to late afternoon. Thus given heating and lower level convergence, scattered light rain showers cannot be ruled out.

IND WATCHES/WARNINGS/ADVISORIES

None.