{"id":67759,"date":"2025-11-10T10:59:00","date_gmt":"2025-11-10T10:59:00","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=67759"},"modified":"2025-11-14T20:38:03","modified_gmt":"2025-11-14T20:38:03","slug":"satellite-indicators-of-thundersnow-during-a-lake-effect-snow-event-in-southern-lake-michigan","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/67759","title":{"rendered":"Satellite indicators of thundersnow during a lake effect snow event in southern Lake Michigan"},"content":{"rendered":"
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1-minute GOES-19 Infrared images with overlays of GLM Flash Extent Density (large blue\/cyan pixels) and GLM Flash Points (white dots), along with plots of surface reports (red) and fixed buoy reports (yellow), from 0501-1000 UTC on 10 November [click to play MP4 animation]<\/p><\/div>\n

1-minute Mesoscale Domain Sector GOES-19 (GOES-East)<\/em>\u00a0Infrared images (above)<\/strong><\/em> showed a lake effect cloud band — exhibiting cloud-top infrared brightness temperatures as cold as -49 C (darker shades of orange) — over far southern Lake Michigan that was moving inland across parts of northwest Indiana and northeast Illinois after midnight on 10 November 2025<\/strong><\/a>. Air temperatures in the mid-30s F flowing across lake buoy<\/strong><\/a> water temperatures of 53\u00baF<\/strong><\/a> created sufficient instability in the marine boundary layer to enhance and sustain these lake effect cloud bands.<\/p>\n

Overlays of GLM<\/strong><\/a> Flash Extent Density and Flash Points highlighted 3 brief instances of satellite-detected lightning activity — along the coast of Indiana at 0519 UTC, and then along the coast of Illinois (near Chicago) at 0622 UTC and 0642 UTC (below)<\/strong><\/em>. Note that the GLM Flash Points are parallax-corrected (to match their location at the surface), while the GLM Flash Extent Density<\/strong><\/a> gridded product is *not* parallax<\/strong><\/a>-corrected (and therefore exhibits a slight NNW displacement in GOES-19 imagery). None of the nearby METAR sites explicitly reported thundersnow or lightning around the times of these GLM signatures.<\/p>\n

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GOES-19 Infrared image at 0519 UTC on 10 November with overlays of GLM Flash Extent Density (large blue\/cyan pixels) and GLM Flash Points (white dots), along with plots of surface reports (red) and fixed buoy reports (yellow) [click to enlarge]<\/p><\/div>\n

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GOES-19 Infrared image at 0622 UTC on 10 November with overlays of GLM Flash Extent Density (large blue\/cyan pixels) and GLM Flash Points (white dots), along with plots of surface reports (red) and fixed buoy reports (yellow) [click to enlarge]<\/p><\/div>\n

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GOES-19 Infrared image at 0642 UTC on 10 November with overlays of GLM Flash Extent Density (large blue\/cyan pixels) and GLM Flash Points (white dots), along with plots of surface reports (red) and fixed buoy reports (yellow) [click to enlarge]<\/p><\/div>\n\n\n

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Thundersnow in Downtown #Chicago<\/a> captured by the Chicago Loop Live webcam! This was the first one around 12:23 am #ilwx<\/a> ????@NWSChicago<\/a> pic.twitter.com\/fBs1C26PDx<\/a><\/p>— Kaitlyn Jesmonth (@wxkaitlynj) November 10, 2025<\/a><\/blockquote>