![](\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/images\/2024\/03\/240323_goes16_visible_surfaceObservations_IA_IL_WI_snow_cover_anim.gif\")
<\/a>GOES-16 “Red” Visible (0.64 \u00b5m) images, with\/without hourly plots of surface observations, from 1301-2001 UTC on 23 March [click to play animated GIF | MP4<\/strong><\/a>]<\/p><\/div>GOES-16 (GOES-East)<\/em> “Red” Visible (0.64 \u00b5m<\/strong><\/a>) images (above)<\/strong><\/em> showed 2 swaths of fresh snow cover across central\/eastern Iowa, far northern Illinois and far southern Wisconsin on 23 March 2024<\/strong><\/a> — which were produced\u00a0 by consecutive systems on 21 March and 22 March (below)<\/strong><\/em>. Total snowfall accumulations contributing to the 22 March southern snow swath included 8.0″ in eastern Iowa and 9.3″ in northern Illinois (NWS Quad Cities<\/strong><\/a> | NWS Chicago<\/strong><\/a>).<\/p>\n As daytime air temperatures warmed as a result of abundant incoming solar radiation, the zone of lesser snow depth (along the Wisconsin\/Illinois border) between the 2 primary swaths of deeper snow cover revealed their northern and southern boundaries. The sharp southern boundary of the Illinois snow cover was particularly notable.<\/p>\n Maps of 24-hour snowfall ending at 1200 UTC on 22 March and 23 March (source<\/strong><\/a>)<\/p><\/div>\n GOES-16 Land Surface Temperature derived product at 1201 UTC, with\/without plots of METAR sites [click to enlarge]<\/p><\/div>The GOES-16 Land Surface Temperature<\/strong><\/a> (LST) derived product at 1201 UTC (above)<\/strong><\/em> revealed several pockets of LST values as cold as +5\u00baF (darker shades of purple) within the swath of snow cover across Iowa and northern Illinois. The coldest minimum shelter air temperature reported<\/strong><\/a> that morning was +9\u00baF at Webster City, Iowa (KEBS), which was located within one of the darker purple pockets of coldest LST.<\/p>\n A toggle between the GOES-16 Land Surface Temperature derived product at 1201 UTC and a Visible image at 1331 UTC (below)<\/strong><\/em> demonstrated how the LST product could be useful for identifying areas where snow depth was likely the greatest (especially in areas having sparse observations) — with deeper snow cover exhibiting a colder LST value.<\/p>\n GOES-16 Land Surface Temperature derived product at 1201 UTC and “Red” Visible image at 1331 UTC [click to enlarge]<\/p><\/div>\n GOES-16 Visible image and Land Surface Temperature derived product at 1301 UTC [click to enlarge]<\/p><\/div>A comparison of GOES-16 Visible and Land Surface Temperature at 1301 UTC (above)<\/strong><\/em> showed that shortly after sunrise the METAR air temperatures were generally several degrees F colder over the deeper snow cover (and colder LSTs), as would be expected — but air temperatures were several degrees warmer than LST values. 5 hours later at 1801 UTC (below)<\/em><\/strong> the air temperatures lagged the rate of warming seen in LST (often by about 20-25\u00baF), especially to the south of snow cover over bare ground in Illinois.<\/p>\n GOES-16 Visible image and Land Surface Temperature derived product at 1801 UTC [click to enlarge]<\/p><\/div>\n _______________________________________<\/p>\n It bears mentioning that some lightning activity was seen during the 22 March snowfall event, with two sites — Cedar Rapids, Iowa (KCID) and Savanna, Illinois (KSFY) — briefly reporting thundersnow<\/strong><\/a>. Toggles between GOES-16 Water Vapor (6.9 \u00b5m<\/strong><\/a>) images + GLM<\/strong><\/a> Flash Extent Density<\/strong><\/a> on 22 March and Visible images on 23 March (below)<\/strong><\/em> indicated that the lightning occurred near the southern edge of the resulting swath of heavy snow across Iowa and Illinois.<\/p>\n<\/a><\/a><\/a><\/a><\/a>