Full Disk JMA Himawari-8 True Color Red-Green-Blue (RGB) images (above) showed the shadow of an annular solar eclipse as it moved from west to east across the Indian Ocean, Indonesia and West Pacific Ocean on 26 December 2019.

A closer view using images centered over Indonesia is shown below. The small eye of Category 1 Typhoon Phanfone could be seen in the northern portion of the satellite scene. Bright areas of sun glint (south of the eclipse shadow) highlighted regions having light winds — and therefore a relatively flat water surface which behaved like a mirror to reflect a larger amount of sunlight back toward the satellite.

The solar eclipse shadow was also seen on Visible (0.73 µm) images from the CMA FY-2G satellite (below), which is positioned father west over the Equator at 105ºE longitude.

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A sequence of GOES-17 (GOES-West) Low-level (7.3 µm), Mid-level (6.9 µm), Upper-level (6.2 µm) Water Vapor and “Clean” Infrared Window (10.35 µm) images (above) showed a long-lived orographic banner cloud that formed in Southern California and extended about 200 miles to the northeast across southern Nevada on 22 December 2019. The banner cloud was formed by anomalously-strong southwesterly winds (925 hPa | 250 hPa) interacting with the high terrain of Southern California’s Transverse Ranges. At the surface, wind gusts as high as 86 mph were observed.

Within the banner cloud, the coldest GOES-17 Infrared brightness temperatures were in the -60 to -65ºC range — according to rawinsonde data from Vandenberg, California (below), those temperatures corresponded to altitudes in the 12-15 km range.

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GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed that most of Antarctica experienced 24 hours of full solar illumination during the Southern Hemisphere’s Summer Solstice on 21 December 2019. Through breaks in the cloud cover, a few bright areas of sun glint were also evident, moving from west to east, due to the reflection of sunlight off ice-free water.

In spite of receiving 24 hours of sunlight, interior areas of the continent remained quite cold — due to high elevation and deep snow cover. For example, surface air temperatures at station 8927 near the center of Antarctica remained within the -25 to -35ºF range on 21 December (source).

In the Northern Hemisphere, GOES-17 (GOES-West) Visible images (below) revealed a few hours of illumination of the southern summits of Denali and nearby portions of the Alaska Range. Note the presence of much colder surface air temperatures (-20s and -30s F) north of the Alaska Range.

Farther to the north across Interior Alaska, some locations reported minimum air temperatures in the -40s to -50s F. A Suomi NPP VIIRS Infrared image (below) showed surface brightness temperatures as cold as -50ºC or -58ºF (brighter yellow enhancement) in the Yukon Flats area around Fort Yukon (PFYU).

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A comparison of GOES-17 (GOES-West) Nighttime Microphysics RGB and “Clean” Infrared Window (10.35 µm) images (above) showed the formation and motion of patchy stratus clouds (RGB shades of yellow) over Interior Alaska on 17 December 2019.  Note how the clouds are difficult to detect and track on the 10.35 µm images, since the temperatures of cold land surfaces and stratus cloud tops were similar. Since these high latitudes receive little to no sufficient solar illumination to allow useful visible imagery during the winter season, the RGB product can be a helpful tool for monitoring the evolution of such low clouds.

Plots of surface data from Bettles (PABT) and Fort Yukon (PFYU) (below) showed that the stratus cloud deck — with bases in the 6,000-10,000 feet range — had an impact on surface air temperature trends, with warming occurring as radiational cooling was slowed and/or reversed as the clouds moved overhead. Temperatures continued to rise at Bettles as the cloud coverage remained broken to overcast, while the temperature briefly dropped again at Fort Yukon as the cloud coverage thinned to scattered.

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