{"id":38648,"date":"2020-10-17T18:03:43","date_gmt":"2020-10-17T18:03:43","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=38648"},"modified":"2020-10-18T22:50:24","modified_gmt":"2020-10-18T22:50:24","slug":"noaa-20-sounder-observations-of-the-atmosphere-during-a-downslope-event","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/38648","title":{"rendered":"NOAA-20 sounder observations of the atmosphere during a downslope event"},"content":{"rendered":"
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GOES-16 Band 10 (7.3 \u00b5m) “Low-level water vapor” infrared imagery, 0831 – 1316 UTC (Click to animate)<\/p><\/div>\n

Low-level water vapor imagery, above, from early morning on 17 October 2020, shows the characteristics of strong low-level winds in the lee of the Colorado Rockies, namely a warm trench and herringbone-like structures that suggest turbulent flow. This region is near the Cameron Peak fire<\/a>, a long-lived conflagration to the west of Fort Collins (previous blog posts on this event are here<\/a>, here<\/a> and here<\/a>).<\/p>\n

Shortwave infrared imagery, below, captures the regions of hottest fire activity, both with Cameron Peak and with the newer East Troublesome fire<\/a> to its southwest. Clouds moving down from the north impede the satellite view of the fires at the end of the animation.<\/p>\n

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GOES-16 Band 7 (3.9 \u00b5m) shortwave infrared imagery, 0921 – 1241 UTC, with surface observation plots (Click to animate)<\/p><\/div>\n

\n

NOAA-20 overflies Colorado twice daily; do the NUCAPS soundings produced from radiances observed by the CrIS (Cross-track Infrared Sounder) and ATMS (Advanced Technology Microwave Sounder) instruments on board NOAA-20 detect atmospheric structures (i.e., inversions) that trap energy and accompany downslope wind events?\u00a0 On 16 October, in the afternoon, NOAA-20 NUCAPS soundings, below, did not show inversions.<\/p>\n

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NOAA-20 NUCAPS Profiles at the locations indicated, at ~1900 UTC on 16 October 2020 (click to enlarge)<\/p><\/div>\n

Similarly, NUCAPS profiles from the morning pass on 17 October, however, around 0900 UTC,\u00a0 did not show mid-tropospheric inversions over eastern Colorado, over the High Plains.<\/p>\n

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NOAA-20 NUCAPS Profiles at the locations indicated, at ~0900 UTC on 17 October 2020 (click to enlarge)<\/p><\/div>\n

Some NUCAPS profiles upstream of the Front Range of the Rockies, however, showed ample evidence of inversions, especially in a region over central Colorado.<\/p>\n

\"\"<\/a>

NOAA-20 NUCAPS Profiles at the locations indicated, at ~0900 UTC on 17 October 2020 (click to enlarge)<\/p><\/div>\n

The 7.3 \u00b5m infrared image (Band 10, low-level water vapor), below, has turbulent structure near the regions where inversions were detected by NUCAPS.<\/p>\n

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GOES-16 ABI Band 10 (7.3 \u00b5m) at 0931 UTC, 17 October 2020. The blue-circled region roughly corresponds to the region where NUCAPS profiles show a mid-tropospheric inversion consistent with downslope winds to the east (Click to enlarge)<\/p><\/div>\n

A wind speed plot from the NCAR Mesa Lab in Boulder, below (source<\/a>), shows the periodic strong and gusty winds on 17 October.<\/p>\n

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Wind speeds and gusts for the 24 hours ending 11:52 MDT (1652 UTC) on 17 October 2020 (Click to enlarge)<\/p><\/div>\n

Use NUCAPS profiles to gauge the strength of the inversion that is associated with downslope events.<\/p>\n

Thanks to Paul Schlatter, SOO at WFO BOU, for the idea for this blog post!<\/p>\n","protected":false},"excerpt":{"rendered":"

Low-level water vapor imagery, above, from early morning on 17 October 2020, shows the characteristics of strong low-level winds in the lee of the Colorado Rockies, namely a warm trench and herringbone-like structures that suggest turbulent flow. This region is near the Cameron Peak fire, a long-lived conflagration to the west of Fort Collins (previous […]<\/p>\n","protected":false},"author":19,"featured_media":38652,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[6,74,78,83],"tags":[],"class_list":["post-38648","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-fire-detection","category-goes-16","category-noaa-20","category-nucaps"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/38648","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/users\/19"}],"replies":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/comments?post=38648"}],"version-history":[{"count":11,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/38648\/revisions"}],"predecessor-version":[{"id":38669,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/38648\/revisions\/38669"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media\/38652"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=38648"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=38648"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=38648"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}