GOES-16 (GOES-East) Day Snow-Fog RGB and Land Surface Temperature product images on 01 January 2021 (above) showed a large portion of western and southwestern Texas in the wake of a winter storm that occurred on the previous day. On the RGB images, snow cover appeared as shades of red, with low clouds and fog taking on shades of white (shades of green denoted bare ground).

Wondering how much snow ? the winter storm brought? ? Here is a map depicting total snow fall amounts. Notice the sharp cutoff between the areas that got snow vs areas that didn’t get any! #TXwx #NMwx #Winterstorm pic.twitter.com/MMCpxTqaYS

— NWS Midland (@NWSMidland) January 1, 2021

With some areas receiving storm total accumulations of 8-15 inches, the deep snow cover kept Land Surface Temperature (LST) values from rising past the low-mid 30s F during the day — even at locations such as Fort Stockton (KFST), which remained generally cloud-free during the daytime hours (their daily maximum temperature was only 36ºF). Over adjacent bare ground areas, LST values rose into the 50s and 60s F with a full day of sunshine. Air temperatures — measured by sheltered sensors located about 5 feet above the ground — were sometimes 10-15ºF cooler than LST values over bare ground, but over deep snow cover the air temperatures were generally only 5-8ºF warmer than the LST values.

===== 02 January Update =====

On the following day, a lack of clouds allowed a good view of the areal coverage of remaining snow cover (above). During the peak of daytime heating, GOES-16 LST values were held to the middle 30s F over the areas with deeper snow cover — while air temperatures rose into the 40s F  (although the daily maximum temperature was only 40 at Big Spring KBPG). Over adjacent areas of bare ground, afternoon air temperatures rising into the 50s and 60s F were seen.

===== 04 January Update =====

A sequence of GOES-16 True Color RGB images during the period 02-04 January created using Geo2Grid (above) showed the gradual melting of most of the snow cover across western Texas.

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As noted here, the ftp site that holds imagery from the CIMSS/SSEC Direct Broadcast site (link) includes daytime True-Color imagery (spectacular imagery!) derived from the NOAA-20 and Suomi-NPP VIIRS instrument. Daily sectorized views of each of the Great Lakes are created, and these can be strung together, as in this web post, to show the changes around the Great Lakes during the month of December. The animation above shows the changes over Lake Superior during December. (Click here to view an mp4 animation rather than the very large animated gif).

The toggle below compares the view over/around Lake Superior on 1 and 31 December 2020. The increase in snowcover is apparent. Ice does not appear widespread on Lake Superior however.  The 31 December 2020 Lake Ice Analysis (image available here) from the Great Lakes Environmental Research Lab (GLERL) (source, from here), shows little ice.  The MIRS Lake Ice Concentration (shown at bottom, available via an LDM feed from CIMSS), similarly shows little ice in the Lakes.

Animations similar to Lake Superior’s can be accessed in this webpost as mp4s: (Lake Michigan, Lake Huron, Lake Erie, Lake Ontario) or as animated gifs (Lake Michigan, Lake Huron, Lake Erie, Lake Ontario).

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GOES-17 (GOES-West) Air Mass RGB and Mid-level Water Vapor (6.9 µm) images (above) showed an anomalously-deep Hurricane Force low pressure system as it approached the western Aleutian Islands and moved into the Bering Sea on 31 December 2020 (surface analyses). The peak wind gust at Shemya (PASY) was 72 knots (83 mph) at 09 UTC.

A closer view using a GOES-17 Water Vapor image at 0910 UTC (below) included plots of Metop ASCAT surface scatterometer winds — the highest ASCAT wind speeds were 66 knots north of the storm center, and 78 knots south of the storm center.

A toggle between Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images (below) showed the cloud circulation associated with the low at 1457 UTC — ample illumination from a Full Moon provided a superb visible image at night.

In another comparison of Suomi NPP VIIRS Infrared Window and Day/Night Band images about 10 hours later at 0053 UTC on 01 January (below), note the ship report approximately 300 miles west-northwest of Shemya: 50 knot winds, with blowing spray (which is plotted with the symbol normally used to indicate blowing sand).

Model fields indicated that the height of the Dynamic Tropopause — taken to be the pressure of the PV1.5 surface — descended to the 600 hPa pressure level as the storm moved across the Shemya area (below).

Of particular significance was the fact that a new low pressure record for the State of Alaska was set when Shemya dropped to 924.8 hPa at 2159 UTC (below).

A new Alaska land-based low pressure record has been set! Shemya, AK dropped to 924.8mb at 2159Z (1259 AKST) today. The previous accepted record was from a ship in Dutch Harbor at 925mb in 1977. Pressure is now slowly rising at Shemya. #akwx #hurricaneforce pic.twitter.com/1yiYOPvsTr

— NWS Anchorage (@NWSAnchorage) December 31, 2020

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1-minute Mesoscale Domain Sector GOES-17 (GOES-West) Night Fog brightness temperature difference (BTD) and “Red” Visible (0.64 µm) images (above) showed the nighttime and daytime signature of a fog/stratus layer that had persisted throughout much of the Snake River Basin in southern Idaho on 29 December 2020. Some sites along the Interstate 84 corridor were reporting freezing fog — and the surface visibility was restricted to less than 1/4 mile at times in Boise (KBOI).

During the preceding nighttime hours, the extent of fog/stratus cloud within the Basin was well-illuminated by a nearly-full Moon (which was in the Waxing Gibbous phase, at 99% of Full) as seen in a Suomi NPP VIIRS image at 0856 UTC (below).

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