{"id":37227,"date":"2020-06-12T23:59:52","date_gmt":"2020-06-12T23:59:52","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=37227"},"modified":"2020-06-14T22:46:31","modified_gmt":"2020-06-14T22:46:31","slug":"cutoff-low-over-northern-alaska","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/37227","title":{"rendered":"Cutoff low over northern Alaska"},"content":{"rendered":"

\"GOES-17<\/a>

GOES-17 Mid-level Water Vapor (6.9 \u00b5m)<\/em> images, with contours of PV1.5 Pressure plotted in red [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>GOES-17 (GOES-West)<\/em> Mid-level Water Vapor (6.9 \u00b5m<\/strong><\/a>) images (above)<\/strong> <\/em>showed the circulation of an anomalous middle-tropospheric cutoff low<\/a><\/strong> over the northwestern portion of Alaska on 12 June 2020. A Potential Vorticity (PV) anomaly associated with this low was causing the dynamic tropopause — represented by the pressure of the PV1.5 surface — to descend as low as the 500 hPa pressure level.<\/p>\n

\"GOES-17<\/a>

GOES-17 Mid-level Water Vapor (6.9 \u00b5m)<\/em> images, with contours of PV1.5 Pressure plotted in red and available NUCAPS sounding profiles denoted by green\/yellow points [click to enlarge]<\/p><\/div>Just after 21 UTC, an overpass of the Suomi NPP satellite provided NUCAPS soundings (above)<\/strong><\/em> within much of the core of the cutoff low — the green NUCAPS sounding profile about 40 miles east\/southeast of the 500 hPa PV1.5 pressure contour (below)<\/strong><\/em> displayed an apparent tropopause near the 400 hPa pressure level.<\/p>\n

\"NUCAPS<\/a>

NUCAPS sounding profile [click to enlarge]<\/p><\/div>GOES-17 “Red” Visible (0.64 \u00b5m<\/strong><\/a>) images (below)<\/strong><\/em> revealed the development of numerous showers and thunderstorms across the Brooks Range and North Slope of Alaska, aided by instability beneath the cutoff low.<\/p>\n

\"GOES-17<\/a>

GOES-17 “Red” Visible (0.64 \u00b5m)<\/em> images, with hourly surface reports plotted in red [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>A higher spatial resolution view of these showers and thunderstorms was provided by a sequence of VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 \u00b5m) images from NOAA-20 and Suomi NPP, as viewed using RealEarth<\/strong><\/a> (below)<\/strong><\/em>. A few of these thunderstorms moved toward the Arctic Coast, with one fairly impressive storm just southwest of Katovik<\/strong><\/a> which exhibited cloud-top infrared brightness temperatures near -60\u00baC (red enhancement)<\/em>\u00a0around 23 UTC.<\/p>\n

\"VIIRS<\/a>

VIIRS True Color (RGB) and Infrared Window (11.45 \u00b5m)<\/em> images from NOAA-20 and Suomi NPP [click to enlarge]<\/p><\/div>

<\/p>\n
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Summer thunderstorms stretched across the North Slope and near the Arctic Coast today. Data from the GLD360 depicted over 800 Cloud-to-Ground lightning events in the area! Here is the scene at Atqasuk, Utqiagvik, Nuiqsut, and Deadhorse this afternoon and evening. #akwx<\/a> #lightning<\/a> pic.twitter.com\/tGeqswONW5<\/a><\/p>\n

\u2014 NWS Fairbanks (@NWSFairbanks) June 13, 2020<\/a><\/p><\/blockquote>\n