While Wisconsin endures a very cold airmass without the brightening benefit of snow, various satellites continue to take spectacular imagery.  The GOES-16 True Color imagery above, from the CSPP Geosphere site, shows a clear scene and snowless features over southern Wisconsin (except over Racine and Kenosha counties in far southeast WI where lake-effect snow fell earlier this month).  The resolution of the GOES-16 Visible channel (Band 2, 0.64 µm) is 0.5 km at the sub-satellite point, meaning an effective resolution of around 1 km over Wisconsin.  NOAA-20 overflew Wisconsin on 19 January and the scene below, from the VIIRS Today website, shows a similar view, but with nominally better resolution:  the visible channels (M03, M04, M05) used to create true-color imagery have 750-m resolution.  The ‘true color’ views do not look the same because of the different wavelengths that are used to create them.

Even better resolution imagery occurred when Sentinel-2A overflew Wisconsin on 17 January 2025 (link; to reproduce the imagery below, change the date at the website that opens; this site also allows a user to view southern California and the effects of recent fires).  The MSI (Multi-Spectral Imager) on Sentinel-2A has 10-m resolution at 0.49, 0.56 and 0.67 micrometers), so it can produce pictures with far higher resolution, but its temporal coverage is restricted.  Madison was lucky on the 17th: full coverage on a clear day. It really is that brown in Wisconsin without snowcover! Your blogger also finds the ice patterns on the lakes fascinating.

A zoomed-in view over Madison’s isthmus, below, includes the UW-Madison campus and the State Capitol.

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Thermal signatures of the still-unfrozen water of Lake Oahe reservoir (along the Missouri River, in central South Dakota) were evident in GOES-16 (GOES-East) Infrared, Low-level Water Vapor and Mid-level Water Vapor images on 19th January 2025 (above). As a result of cold arctic air (morning low temperatures across western/central SD were generally in the -10 to -20F range) flowing across the open water of Lake Oahe, there were also 2 brief periods of light lake effect snow at Pierre (KPIR), each which reduced the surface visibility to 2.5 miles (below).

With a cold/dry arctic air mass in place over the region, the GOES-16 Mid-level Water Vapor (Band 09) and Low-level Water Vapor (Band 10) weighting functions peaked at lower than normal altitudes (below) — with significant amounts of radiation from the surface reaching the satellite detectors (thereby enabling a signature of Lake Oahe in the Water Vapor imagery).

In fact, the Total Precipitable Water value derived from 1200 UTC Rapid City rawinsonde data (0.03 in) (above) was a record low value for 1200 UTC soundings on 19 January (below).

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) Visible images (above) revealed horizontal Convective Roll (HCR) clouds that are often associated with areas where blowing snow is occurring — such as was the case across parts of eastern North Dakota and western Minnesota on 17th January 2025. With strong N-NW winds (in the wake of an arctic cold front) gusting as high as 67 mph in ND and 65 mph in MN, widespread blowing snow was reducing the surface visibility to near zero at some locations. Interstate 29 was closed from Grand Forks (KGFK) to the Canadian border.

1-minute GOES-16 Blowing Snow RGB images created using Geo2Grid (below) provided a clearer depiction of where the HCRs coincided with blowing snow. Existing snow cover appeared as darker shades of red in the RGB imagery, while bare ground appeared as brighter shades of green; supercooled water droplet clouds appeared as brighter shades of white, with mixed phase or glaciating clouds taking on pale shades of green.

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5-minute CONUS Sector GOES-19 (Preliminary/Non-operational) True Color RGB images — created using Geo2Grid (below) displayed ice in southwestern/southern Lake Michigan that was being driven away from the coastlines of Wisconsin, Illinois and Indiana by gusty NW winds on 14th January 2025.

GOES-16 (GOES-East) Visible images (below) included plots of surface and buoy reports — which showed wind gusts in the 25-30 knot range at several sites near the Lake Michigan coast.

The presence of lake ice off the southwestern/southern coast of Lake Michigan was confirmed by a Water Temperature analysis (above) and Synthetic Aperture Radar (SAR) data (below). Lake ice in SAR imagery exhibits high backscatter values, represented by the yellow to red colors normally associated with higher wind speeds.

A longer sequence of GOES-19 True Color RGB images during the daytime hours on 13/14/15 January (below) revealed a gradual growth in nearshore ice across southwestern/southern Lake Michigan during that 3-day period, as cold air remained in place across that area.

A Landsat-9 Natural Color RGB image at 1635 UTC on 16th January (below) showed a high-resolution view of Lake Michigan ice (pale shades of cyan) off the coast near Chicago.

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