{"id":427,"date":"2026-08-13T11:53:04","date_gmt":"2026-08-13T16:53:04","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/?p=427"},"modified":"2026-08-13T11:55:14","modified_gmt":"2026-08-13T16:55:14","slug":"even-more-mcss","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/2026\/08\/13\/even-more-mcss\/","title":{"rendered":"Even more MCSs"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Multiple MCSs were riding a ridge of high theta-e air over the middle of the U.S. Over 900 wind reports were recorded from South Dakota to South Carolina, with the highest concentration from Illinois to West Virginia. Multiple tornadoes were recorded, including an EF2 tornado in the southwest Chicago suburbs.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"697\" src=\"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-content\/uploads\/sites\/29\/2026\/08\/image-2-1024x697.png\" alt=\"\" class=\"wp-image-429\" srcset=\"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-content\/uploads\/sites\/29\/2026\/08\/image-2-1024x697.png 1024w, https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-content\/uploads\/sites\/29\/2026\/08\/image-2-300x204.png 300w, https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-content\/uploads\/sites\/29\/2026\/08\/image-2-768x523.png 768w, https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-content\/uploads\/sites\/29\/2026\/08\/image-2-1536x1046.png 1536w, https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-content\/uploads\/sites\/29\/2026\/08\/image-2.png 1630w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">While the operational ProbSevere v3 performed well, the experimental ProbSevere v4, which is more spatially aware, surpassed it in many areas. The video below shows the PSv4 contours, along with reports valid 0-45 minutes after the timestamp of the image. The PSv4 model tries to predict the probability of severe reports within 15 km and 45 minutes of a point.<\/p>\n\n\n\n<figure class=\"wp-block-video\"><video height=\"720\" style=\"aspect-ratio: 1280 \/ 720;\" width=\"1280\" controls src=\"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-content\/uploads\/sites\/29\/2026\/08\/ps_20260811.mp4\"><\/video><figcaption class=\"wp-element-caption\">ProbSevere v4 probabilities (contours), preliminary local storm reports 0-45 minutes after the image timestamp (circles), NWS severe weather warnings (orange and red polygons) and MRMS MergedReflectivity (background).<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">PSv4 had higher swaths of probability (compared to PSv3 objects) when lines became less intense. However, both models struggled when lines weakened considerably in terms of reflectivity and lightning. You can see this in north-central Indiana and northern West Virginia, where there were several clusters of wind reports in decaying line segments. Clearly, the momentum of such lines is being transported to the ground, even during decay. These are cases that require further investigation.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">It was encouraging to see several things in this case. Please refer to the figure below:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The strongest probabilities were with the strongest line of storms, in northern Illinois<\/li>\n\n\n\n<li>There is very little &#8220;wasted&#8221; probability contours on the backsides of these MCSs. By contrast, there is much severe thunderstorm warning area on the backsides that could be pruned.<\/li>\n\n\n\n<li>The PSv4 probability swaths are further ahead of the storms, compared to warnings. You see this in Illinois and in southern Ohio. This helps produce longer and more equitable lead times, especially when coupled with the rapid updates of PSv4.<\/li>\n\n\n\n<li>In southern Ohio\/northeast Kentucky, moderate probabilities (~25%) were seen for a couple cluster of reports. It appears the model correctly anticipated developing storms in southwest Ohio might produce severe weather, but with &#8220;hedging&#8221; probabilities that the NWS warnings missed.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"671\" src=\"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-content\/uploads\/sites\/29\/2026\/08\/iTerm2.FXl6TG.PS_20260811-1500-1024x671.png\" alt=\"\" class=\"wp-image-431\" srcset=\"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-content\/uploads\/sites\/29\/2026\/08\/iTerm2.FXl6TG.PS_20260811-1500-1024x671.png 1024w, https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-content\/uploads\/sites\/29\/2026\/08\/iTerm2.FXl6TG.PS_20260811-1500-300x197.png 300w, https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-content\/uploads\/sites\/29\/2026\/08\/iTerm2.FXl6TG.PS_20260811-1500-768x503.png 768w, https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-content\/uploads\/sites\/29\/2026\/08\/iTerm2.FXl6TG.PS_20260811-1500.png 1062w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">ProbSevere v4 probabilities (contours), preliminary local storm reports 0-45 minutes after the image timestamp (circles), NWS severe weather warnings (orange polygons) and MRMS MergedReflectivity (background).<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Multiple MCSs were riding a ridge of high theta-e air over the middle of the U.S. Over 900 wind reports were recorded from South Dakota to South Carolina, with the highest concentration from Illinois to West Virginia. Multiple tornadoes were recorded, including an EF2 tornado in the southwest Chicago suburbs. While the operational ProbSevere v3 [&hellip;]<\/p>\n","protected":false},"author":14,"featured_media":431,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[5],"tags":[6],"class_list":["post-427","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-psv4","tag-psv4"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/posts\/427","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/users\/14"}],"replies":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/comments?post=427"}],"version-history":[{"count":3,"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/posts\/427\/revisions"}],"predecessor-version":[{"id":434,"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/posts\/427\/revisions\/434"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/media\/431"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/media?parent=427"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/categories?post=427"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/tags?post=427"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}