Minor Snow Squalls across NRN Indiana // 18 December 2023

 Low-level convergence was maximized along the southeast lee-side of Lake Michigan during 18 December 2023 and aided in the generation of mainly non-impactful snow squalls. Squalls moved southeast across Northern Indiana during late morning and early afternoon, generally becoming aligned with the 0-3 km mean flow. Midlevel temperatures centered within cyclonic flow aloft were very cold (near -30C at 500 mb), and low-level lapse rates were steep (~7 C/km), which yielded MUCAPE values close to 100 J/kg. The mean boundary layer wind speed was also around 30 kt, which supported periods of gusty winds occurring with maximal mixing in stronger squalls. Although impacts were mainly non-existent, I was entertained as this was my first experience with lake enhanced snowfall.

Early afternoon base reflectivity from the KIXW radar. Note the initiation of snow showers on the southeast side of Lake Michigan, and loosely organized bands extending southeastward across SWRN MI and NRN IN.

Water vapor imagery showing the large-scale pattern over the Great Lakes region. Cyclonic flow aloft was positioned across the area associated with an upper trough. Snow showers formed on the western periphery of the trough.

Northern Indiana NAM NEST forecast sounding valid 18 UTC 18 December 2023. A humid steep-lapse rate environment characterized the boundary layer, and flow was moderately strong out of the northwest.

500 mb SPC mesoanalysis chart valid at 18 UTC 18 December 2023. A very cold airmass (~-30C) was located within the western periphery of the trough situated over the Great Lakes region.

Steep 0-3 km lapse rates were positioned southeast downstream from Lake Michigan over SRN MI and NRN IN.

Boundary layer convergence was maximized along the southeast lee-side of Lake Michigan and aided in snow shower initiation. Showers then developed into loosely organized northwest-southeast oriented bands aligned with the mean boundary layer flow.

Non-zero snow-squall parameter values were located east and south of Lake Michigan. Perhaps a useful signal for future snow-squallish activity.