{"id":39463,"date":"2020-12-31T23:59:11","date_gmt":"2020-12-31T23:59:11","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=39463"},"modified":"2021-01-01T22:35:49","modified_gmt":"2021-01-01T22:35:49","slug":"hurricane-force-low-moves-into-the-bering-sea","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/39463","title":{"rendered":"Hurricane Force low moves into the Bering Sea"},"content":{"rendered":"

\"GOES-17<\/a>

GOES-17 Air Mass RGB and Mid-level Water Vapor (6.9 \u00b5m)<\/em> images [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>GOES-17 (GOES-West)<\/em> Air Mass RGB<\/strong><\/a> and Mid-level Water Vapor (6.9 \u00b5m<\/strong><\/a>) images (above)<\/strong> <\/em>showed an anomalously-deep<\/a><\/strong> Hurricane Force low pressure system as it approached the western Aleutian Islands and moved into the Bering Sea on 31 December 2020 (surface analyses<\/a><\/strong>). The peak wind gust at Shemya (PASY) was 72 knots (83 mph) at 09 UTC.<\/p>\n

A closer view using a GOES-17 Water Vapor image at 0910 UTC (below)<\/strong> <\/em>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.<\/p>\n

\"GOES-17<\/a>

GOES-17 Mid-level Water Vapor (6.9 \u00b5m)<\/em> image at 0910 UTC, with plots of Metop ASCAT surface scatterometer winds [click to enlarge]<\/p><\/div>A toggle between Suomi NPP VIIRS Infrared Window (11.45 \u00b5m) and Day\/Night Band (0.7 \u00b5m) images (below)<\/strong><\/em> showed the cloud circulation associated with the low at 1457 UTC — ample illumination from a Full Moon provided a superb visible image at night.<\/p>\n

\"Suomi<\/a>

Suomi NPP VIIRS Infrared Window (11.45 \u00b5m)<\/em> and Day\/Night Band (0.7 \u00b5m)<\/em> images [click to enlarge]<\/p><\/div>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)<\/strong>,<\/em> 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).<\/p>\n

\"Suomi<\/a>

Suomi NPP VIIRS Infrared Window (11.45 \u00b5m)<\/em> and Day\/Night Band (0.7 \u00b5m)<\/em> images [click to enlarge]<\/p><\/div>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)<\/strong><\/em>.<\/p>\n

\"GOES-17<\/a>

GOES-17 Mid-level Water Vapor (6.9 \u00b5m)<\/em> images, with contours of PV1.5 pressure [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>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)<\/strong><\/em>.<\/p>\n

\"Plot<\/a>

Plot of surface report data from Shemya [click to enlarge]<\/p><\/div>
\n

<\/p>\n
\n

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<\/a> #hurricaneforce<\/a> pic.twitter.com\/1yiYOPvsTr<\/a><\/p>\n

\u2014 NWS Anchorage (@NWSAnchorage) December 31, 2020<\/a><\/p><\/blockquote>\n