{"id":2363,"date":"2009-12-01T13:53:34","date_gmt":"2009-12-01T18:53:34","guid":{"rendered":"http:\/\/www.norman.noaa.gov\/?p=1336"},"modified":"2009-12-01T13:53:34","modified_gmt":"2009-12-01T18:53:34","slug":"u-s-tornado-droughts-since-1990","status":"publish","type":"post","link":"https:\/\/inside.nssl.noaa.gov\/nsslnews\/2009\/12\/u-s-tornado-droughts-since-1990\/","title":{"rendered":"U.S. tornado droughts since 1990"},"content":{"rendered":"<p><span style=\"font-family: PrimaSans BT,Verdana,sans-serif\">Preliminary reports indicate that 23 days passed between November 7th and 29th, 2009 without a single tornado report in the continental United States. That period turns out to be about the average duration of an annual\u00a0 tornado drought based on recent records.<br \/>\n<\/span><\/p>\n<p><span style=\"font-family: PrimaSans BT,Verdana,sans-serif\">The U.S. should experience tornado droughts spanning a little over 20 days about once per year. The longest tornado-free span in the last two decades occurred over a 45 day period from December 31, 2002 through mid-February, 2003.<\/span><\/p>\n<p><span style=\"font-family: PrimaSans BT,Verdana,sans-serif\">Other tornado droughts in the longer-term record include the following:<\/span><\/p>\n<p><span style=\"font-family: PrimaSans BT,Verdana,sans-serif\">57 days, ending on Nov. 14, 1952.<br \/>\n54 days, ending on Jan. 28, 1956.<br \/>\n52 days, ending on Feb. 2, 1986.<br \/>\n45 days, ending on Jan. 19, 1961.<br \/>\n45 days, ending on Jan. 22, 1981.<\/span><\/p>\n<p>In an attempt to better visualize tornado &#8220;drought&#8221; durations, and where those episodes have occurred on the calendar, I put together a chart depicting the longest annual tornado droughts since 1990.<\/p>\n<p><a href=\"https:\/\/inside.nssl.noaa.gov\/nsslnews\/wp-content\/uploads\/sites\/21\/2009\/12\/tordroughts.png\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-large wp-image-2397\" src=\"https:\/\/inside.nssl.noaa.gov\/nsslnews\/wp-content\/uploads\/sites\/21\/2009\/12\/tordroughts-632x391.png\" alt=\"U.S. Tornado Droughts (1990-2009)\" width=\"600\" height=\"371\" \/><\/a><\/p>\n<p><span style=\"font-family: PrimaSans BT,Verdana,sans-serif\">This chart seems to indicate that most November tornado droughts are relatively short in duration. There have been six November droughts in the last 20 years. The November 2002 drought was the longest, at 30 days, and continued into December before ending. Over half (11) of the tornado droughts began or ended in December but it is not uncommon for tornado droughts to span January\/February too.<\/span><\/p>\n<p><span style=\"font-family: PrimaSans BT,Verdana,sans-serif\">There are other times in the year when there may not be a tornado for a few days, or up to a week. Those spans are not shown here. Analysis of the records suggests that our most recent tornado-free November ended just about on schedule after 23 days.<\/span><\/p>\n<p><span style=\"font-family: PrimaSans BT,Verdana,sans-serif\">Incidentally, the <a href=\"http:\/\/www.spc.noaa.gov\/\">Storm Prediction Center<\/a> (SPC) issued no Tornado or Severe Thunderstorm Watches during November 2009. This is the <span style=\"text-decoration: underline\">only<\/span> November in the watch database (since 1970) when no watches have been issued during the month. But, that&#8217;s a subject for another post, perhaps!<br \/>\n<\/span><\/p>\n<p><span style=\"font-family: PrimaSans BT,Verdana,sans-serif\">Harold Brooks has been conducting a return period analysis on the tornado record for different tornado (E)F scales. He is likely to provide additional insight in an upcoming blog post on this subject so stay tuned!<br \/>\n<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>How does the 23-day tornado drought in November 2009 compare with other years?<\/p>\n","protected":false},"author":66,"featured_media":2397,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_eb_attr":"","ghostkit_customizer_options":"","ghostkit_custom_css":"","ghostkit_custom_js_head":"","ghostkit_custom_js_foot":"","ghostkit_typography":"","footnotes":""},"categories":[14],"tags":[],"class_list":["post-2363","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-svr-wx"],"acf":[],"wps_subtitle":"","_links":{"self":[{"href":"https:\/\/inside.nssl.noaa.gov\/nsslnews\/wp-json\/wp\/v2\/posts\/2363","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/inside.nssl.noaa.gov\/nsslnews\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/inside.nssl.noaa.gov\/nsslnews\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/inside.nssl.noaa.gov\/nsslnews\/wp-json\/wp\/v2\/users\/66"}],"replies":[{"embeddable":true,"href":"https:\/\/inside.nssl.noaa.gov\/nsslnews\/wp-json\/wp\/v2\/comments?post=2363"}],"version-history":[{"count":0,"href":"https:\/\/inside.nssl.noaa.gov\/nsslnews\/wp-json\/wp\/v2\/posts\/2363\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/inside.nssl.noaa.gov\/nsslnews\/wp-json\/wp\/v2\/media\/2397"}],"wp:attachment":[{"href":"https:\/\/inside.nssl.noaa.gov\/nsslnews\/wp-json\/wp\/v2\/media?parent=2363"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/inside.nssl.noaa.gov\/nsslnews\/wp-json\/wp\/v2\/categories?post=2363"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/inside.nssl.noaa.gov\/nsslnews\/wp-json\/wp\/v2\/tags?post=2363"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}