{"id":334,"date":"2026-05-12T08:49:42","date_gmt":"2026-05-12T13:49:42","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/?p=334"},"modified":"2026-05-12T08:49:42","modified_gmt":"2026-05-12T13:49:42","slug":"low-lightning-lines","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/2026\/05\/12\/low-lightning-lines\/","title":{"rendered":"Low-Lightning Lines"},"content":{"rendered":"\n

The severity of convective lines with low total lightning activity (generally < 5 fl\/min) can be difficult to predict, especially prior to the onset of severe hazards being produced. They’re difficult to predict in part because there aren’t often regions that stick out. Cores of storms tend to blend in with the rest of the line. Furthermore, damaging wind reports occur in what looks like weaker parts of the line.<\/p>\n\n\n\n

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ProbSevere v4 (contours), MRMS MergedReflectivity (background), NWS severe weather warnings (red and orange polygons), and preliminary severe wind reports (blue dots) in the NEXT 45 minutes after the image timestamp.<\/figcaption><\/figure>\n\n\n\n

In the eastern Great Lakes region, we had a sweeping cold front come through last weekend. Severe wind reports valid in the ensuing 45 minutes from the image stamp are plotted. These correspond to the “truth” that ProbSevere v4 is trying to predict (the probability of severe weather in the next 45 minutes). You can see that the PSv4 model has low probabilities overall. Generally 10-25%, with some higher maxima < 50%. The effective shear (35-45 kt) and low-level mean wind (40 kt) were decent, as well as the 0-3 km lapse rate (8.5-9.0 C\/km), all important predictors in this type of regime. The lack of lightning, robust reflectivity, and strong azimuthal shears probably kept predictions lower over an extended area, as it couldn’t localize where the greatest threat may be. You often see large severe thunderstorm warnings in these scenarios, too, as humans often have a hard time picking out where there may be damaging wind mixing down in the atmosphere (in the absence of a robust doppler velocity signature).<\/p>\n\n\n\n

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ProbSevere v4 (contours), MRMS MergedReflectivity (background), NWS severe weather warnings (red and orange polygons), and preliminary severe wind reports (blue dots) in the NEXT 45 minutes after the image timestamp.<\/figcaption><\/figure>\n\n\n\n

Further northeast in western New York, we can see large warnings issued by NWS, on the order of 3-4 counties in area. There are a number of severe wind reports, but again, it is appears difficult to pinpoint where wind damage may occur both for forecasters and for the PSv4 model. However, the orientation of the line is more north-south oriented, which may be helping the model here to have a bit more robust probabilities, evidenced by larger areas of \u2265 25% contour.<\/p>\n\n\n\n

The boundary of the 10% PSv4 contour matches well with the boundary of the NWS severe thunderstorm warning.<\/p>\n\n\n\n

\"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

The severity of convective lines with low total lightning activity (generally < 5 fl\/min) can be difficult to predict, especially prior to the onset of severe hazards being produced. They’re difficult to predict in part because there aren’t often regions that stick out. Cores of storms tend to blend in with the rest of the […]<\/p>\n","protected":false},"author":14,"featured_media":339,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[5],"tags":[],"class_list":["post-334","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-psv4"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/posts\/334","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=334"}],"version-history":[{"count":3,"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/posts\/334\/revisions"}],"predecessor-version":[{"id":340,"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/posts\/334\/revisions\/340"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/media\/339"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/media?parent=334"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/categories?post=334"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/probsevere\/wp-json\/wp\/v2\/tags?post=334"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}