Lake Erie lake effect snow band produces thundersnow in western New York
1-minute Mesoscale Domain Sector GOES-16 (GOES-East) Day Cloud Phase Distinction RGB images with an overlay of GLM Flash Extent Density (above) showed a glaciating (brighter shades of green) to glaciated (pale shades of yellow) lake effect snow (LES) band streaming inland off Lake Erie on 17 November 2023. There were 4 brief periods of lightning activity seen just south of the Buffalo, New York metro area. Note: since Flash Extent Density (FED) values were relatively low, the maximum value of the default FED colormap range was adjusted to 2.5 (to emphasize peaks within the low-FED areas).
A closer view (below) showed that the FED-indicated lightning activity was centered over the Southtowns (southern suburbs) of Boston — which had received up to 8.5 inches of snow by about 2300 UTC on 27 Novembver.
Cursor sampling of 2-km resolution GOES-16 CLAVR-x Cloud Top Temperature and Cloud Top Height derived products (below) indicated that the coldest cloud top temperatures within the lightning-producing LES band were in the -18 to -19°C range, with maximum cloud top heights in the 12000-13000 ft range.
During the next several hours, the LES cloud band slowly migrated southward — GOES-16 Nighttime Microphysics RGB images with an overlay of GLM Flash Extent Density (below) suggested that the cloud tops were mixed phase (ice crystals and supercooled water droplets — shades of tan to light brown), which is a necessary condition for charge separation processes within the cloud that lead to lightning production. Another favorable thundersnow factor was a sufficiently high -10°C air temperature level of 1.1 km (reference), as seen in 0000 UTC Buffalo rawinsonde data.
Beginning at 0253 UTC on 28 November, notable bursts of FED lightning activity were seen in the vicinity of Chautauqua County/Dunkirk Airport (KDKK) — which reported a thunderstorm (TS) that lasted from from 0257 UTC to 0312 UTC, and thundersnow (TSSN) at 0306 UTC (below). The surface visibility at that site dropped from 6 miles at 0310 UTC to 1-1/4 mile at 0320 UTC. Thanks to Rick DiMaio (Loyola University) for bringing these KDKK observations to our attention.