{"id":15917,"date":"2021-09-04T08:44:27","date_gmt":"2021-09-04T14:44:27","guid":{"rendered":"https:\/\/www.coloradofloodthreat.com\/?p=15917"},"modified":"2021-09-05T08:11:05","modified_gmt":"2021-09-05T14:11:05","slug":"spm-09-04-2021","status":"publish","type":"post","link":"https:\/\/archive-coftb.dewberryanalytics.com\/?p=15917","title":{"rendered":"SPM 09-04-2021: Widespread, Severe Thunderstorms for Urban Corridor, Palmer Ridge, and Eastern Plains"},"content":{"rendered":"<p>Issue Date: Saturday, September 4th, 2021<br>\nIssue Time: 10:05 AM MDT<\/p>\n<h3>Summary:<\/h3>\n<p>The end of the work week began with early morning showers and storms lingering around the Northeast Plains and Palmer Ridge before lifting and dissipating with the general eastward movement. However, it was not long before more <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;widespread&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;greater than 60% areal coverage&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>widespread<\/span> thunderstorm development across the state, including the necessary moisture and lift needed for some severe weather. <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;scattered&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;25-40% areal coverage&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>Scattered<\/span> thunderstorms began firing up in the late morning and early afternoon in the Northern, Central, and Front Range Mountains, moving eastward onto the Urban Corridor and becoming more organized. As the afternoon progressed, storms formed in the Western Slopes and Grand Valley as well. There was less available moisture for heavy rainfall west of the <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;Divide&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;&amp;lt;!-- wp:paragraph {&amp;quot;textColor&amp;quot;:&amp;quot;white&amp;quot;} --&amp;gt;\n&amp;lt;p class=&amp;quot;has-white-color has-text-color&amp;quot;&amp;gt;the dividing line that separates the watersheds of the western and eastern United States; rivers west of the divide empty into the Pacific Ocean, while rivers east of the divide empty into the Atlantic Ocean or Gulf of Mexico&amp;lt;\/p&amp;gt;\n&amp;lt;!-- \/wp:paragraph --&amp;gt;&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>divide<\/span>, but a different story to the east.<\/p>\n<p>An early afternoon <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;severe thunderstorm&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Thunderstorms that produce a tornado, winds of at least 58 mph (50 kts) and\/or hail at least 1&amp;quot; in diameter.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>severe thunderstorm<\/span> made its way across the South Denver Metro Area, causing 0.50-1.00 hail reports across a large swatch of the southern suburbs: Lakewood, Littleton, Highlands Ranch, and near Chatfield Reservoir. High winds were also reported &ndash; up to 64 mph gusts at KAPA in Centennial. Hail wasn&rsquo;t just large, there was enough to blanket the ground like snow Littleton!<\/p>\n<blockquote class=\"twitter-tweet tw-align-center\">\n<p dir=\"ltr\" lang=\"en\">This is what Littleton CO hail storm looked like at my place yesterday.<a href=\"https:\/\/twitter.com\/hashtag\/cowx?src=hash&amp;ref_src=twsrc%5Etfw\">#cowx<\/a> <a href=\"https:\/\/twitter.com\/9NEWSWeather?ref_src=twsrc%5Etfw\">@9NEWSWeather<\/a> <a href=\"https:\/\/twitter.com\/KDVR?ref_src=twsrc%5Etfw\">@KDVR<\/a> <a href=\"https:\/\/twitter.com\/hashtag\/cohail?src=hash&amp;ref_src=twsrc%5Etfw\">#cohail<\/a> <a href=\"https:\/\/twitter.com\/hashtag\/hail?src=hash&amp;ref_src=twsrc%5Etfw\">#hail<\/a> <a href=\"https:\/\/twitter.com\/hashtag\/SaturdayMorning?src=hash&amp;ref_src=twsrc%5Etfw\">#SaturdayMorning<\/a> <a href=\"https:\/\/t.co\/fAhvPKRitw\">pic.twitter.com\/fAhvPKRitw<\/a><\/p>\n<p>&mdash; Eric Graham (@egraham70) <a href=\"https:\/\/twitter.com\/egraham70\/status\/1434154310963654658?ref_src=twsrc%5Etfw\">September 4, 2021<\/a><\/p><\/blockquote>\n<p><script async src=\"https:\/\/platform.twitter.com\/widgets.js\" charset=\"utf-8\"><\/script><\/p>\n<p><strong>The Centennial Airport also received 1.62 inches of rain yesterday with most of that, 1.57 inches, falling in a single hour.<\/strong> Precipitation Frequency Estimates from NOAA Atlas 14 in this area put 1.57 inches in an hour to be between a 10-year and 25-year event or 4-10% chance of occurrence in any given year. <strong>Other high precipitation totals around the South Denver Metro Area include 1.64 in Highlands Ranch, 1.35 in Littleton, 1.29 in Parker, and 0.97 in Aurora.<\/strong><\/p>\n<p><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/mm_time_chart_dyn-1.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-15925\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/mm_time_chart_dyn-1.png\" alt=\"\" width=\"600\" height=\"270\" srcset=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/mm_time_chart_dyn-1.png 600w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/mm_time_chart_dyn-1-300x135.png 300w\" sizes=\"(max-width: 600px) 100vw, 600px\"\/><\/a><\/p>\n<p>The heavy rain and hail caused street flooding across the area, prompting response from South Metro Fire Rescues for vehicles stranded in high water.<\/p>\n<blockquote class=\"twitter-tweet tw-align-center\">\n<p dir=\"ltr\" lang=\"en\">SMFR is responding to <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;severe thunderstorm&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Thunderstorms that produce a tornado, winds of at least 58 mph (50 kts) and\/or hail at least 1&amp;quot; in diameter.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>severe thunderstorm<\/span> related incidents including several vehicles stranded in high water. No injuries have occurred and no rescues have been needed. Please do not drive into water of unknown depth. <a href=\"https:\/\/twitter.com\/hashtag\/COwx?src=hash&amp;ref_src=twsrc%5Etfw\">#COwx<\/a> <a href=\"https:\/\/t.co\/NikFFS5lnK\">pic.twitter.com\/NikFFS5lnK<\/a><\/p>\n<p>&mdash; South Metro Fire Rescue (@SouthMetroPIO) <a href=\"https:\/\/twitter.com\/SouthMetroPIO\/status\/1433881324796874756?ref_src=twsrc%5Etfw\">September 3, 2021<\/a><\/p><\/blockquote>\n<p><script async src=\"https:\/\/platform.twitter.com\/widgets.js\" charset=\"utf-8\"><\/script><\/p>\n<p>The storms quickly moved off the Urban Corridor with eastward movement of the <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;trough&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;An elongated area of relatively low atmospheric pressure; the opposite of a ridge.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>trough<\/span> axis, forming a line of storms from the northeast corner of the state all the way to Colorado Springs in the afternoon. Fast-moving storms produced heavy rainfall across the Northeast Plains and Palmer Ridge including:<strong> 1.95 inches in Burlington, 1.40 inches in Vernon, 1.30 inches in Woodrow, 0.93 inches in Akron, and 0.71 inches south of Greeley<\/strong>.<\/p>\n<p>A second round of thunderstorms on the Southeast Plains prompted three <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;severe thunderstorm&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Thunderstorms that produce a tornado, winds of at least 58 mph (50 kts) and\/or hail at least 1&amp;quot; in diameter.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>severe thunderstorm<\/span> warnings for counties on the Colorado-Kansas border overnight. Up to 57 mph wind gusts were reported in Aroya, CO. Storms continued well into the early morning hours before moving eastward out of the state, but not before dropping impressive, and much needed, heavy rain. Rainfall totals in Southeast Colorado include: <strong>1.95 inches in Holly, 1.94 in Timpas, 1.40 in Haswell, 1.33 in Rocky Ford, and 1.00 inch in Lamar.<\/strong> The 1.95 inches in Holly was likely also in just under an hour, with PF estimates placing this event between a 2-year and 5-year rainfall event (20-50% chance in any given year).<\/p>\n<p>Further west, a <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;flash flood&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;&amp;lt;!-- wp:paragraph {&amp;quot;textColor&amp;quot;:&amp;quot;white&amp;quot;} --&amp;gt;\n&amp;lt;p class=&amp;quot;has-white-color has-text-color&amp;quot;&amp;gt;flash flooding can refer to usually dry areas becoming rapidly inundated with water, or rapid water level rises on streams, creeks, or rivers beyond flood stage; typically caused by heavy rainfall, but can also be caused by meltwater&amp;lt;\/p&amp;gt;\n&amp;lt;!-- \/wp:paragraph --&amp;gt;&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>flash flood<\/span> <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;Warning&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;&amp;lt;!-- wp:paragraph {&amp;quot;textColor&amp;quot;:&amp;quot;white&amp;quot;} --&amp;gt;\n&amp;lt;p class=&amp;quot;has-white-color has-text-color&amp;quot;&amp;gt;a weather warning is issued when a specific weather event is imminent or occurring&amp;lt;\/p&amp;gt;\n&amp;lt;!-- \/wp:paragraph --&amp;gt;&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>warning<\/span> was issued for the Grizzly Creek burn scar in Glenwood Canyon after 4:00 pm yesterday, which prompted an I-70 safety closure. Up to 0.60 inches of rain fell yesterday in Glenwood Springs and the surrounding area of Glenwood Canyon. Fortunately, no flooding or debris flows were reported and I-70 reopened last night.<\/p>\n<p>For rainfall estimates in your area, check out the State Precipitation Map below.<\/p>\n<h4 class=\"collapseomatic \" id=\"id6a1c1bcfe7e30\" tabindex=\"0\" title=\"Click Here For Map Overview\">Click Here For Map Overview<\/h4><div id=\"target-id6a1c1bcfe7e30\" class=\"collapseomatic_content \">\nThe map below shows radar-estimated, rainfall gage-adjusted Quantitative Precipitation Estimates (<span class=\"glossaryLink\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;QPE&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;&amp;lt;strong&amp;gt;Q&amp;lt;\/strong&amp;gt;uantitative &amp;lt;strong&amp;gt;P&amp;lt;\/strong&amp;gt;recipitation &amp;lt;strong&amp;gt;E&amp;lt;\/strong&amp;gt;stimate; an estimate of the amount of precipitation that has fallen at a particular location or across a region based on several different data sources, such as radar or satellite; QPE is often calculated using remotely-sensed data sources&lt;\/div&gt;\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>QPE<\/span>) across Colorado. The map is updated daily during the operational season (May 1 &ndash; Sep 30) by 11AM. The following six layers are currently available: 24-hour, 48-hour and 72-hour total precipitation, as well as maximum 1-hour, 2-hour and 6-hour precipitation over the past 24 hour period (to estimate where <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;flash flooding&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;&amp;lt;!-- wp:paragraph {&amp;quot;textColor&amp;quot;:&amp;quot;white&amp;quot;} --&amp;gt;\n&amp;lt;p class=&amp;quot;has-white-color has-text-color&amp;quot;&amp;gt;flash flooding can refer to usually dry areas becoming rapidly inundated with water, or rapid water level rises on streams, creeks, or rivers beyond flood stage; typically caused by heavy rainfall, but can also be caused by meltwater&amp;lt;\/p&amp;gt;\n&amp;lt;!-- \/wp:paragraph --&amp;gt;&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>flash flooding<\/span> may have occurred). The accumulation ending time is 7AM of the date shown in the bottom right corner. Also shown optionally are vulnerable fire burn areas (post 2012), which are updated throughout the season to include new, vulnerable burn areas. The home button in the top left corner resets the map to the original zoom.<br><\/div>\n<p><img loading=\"lazy\" src=\"http:\/\/www.dewberry-hydromet.com\/STP\/Snapshots\/SPM\/SPM_20210904_snap.png\" width=\"880\" height=\"616\" class=\"alignnone size-large\"\/><\/p>","protected":false},"excerpt":{"rendered":"<p>Issue Date: Saturday, September 4th, 2021 Issue Time: 10:05 AM MDT Summary: The end of the work week began with early morning showers and storms lingering around the Northeast Plains and Palmer Ridge before lifting and dissipating with the general eastward movement. However, it was not long before more <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;widespread&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;greater than 60% areal coverage&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>widespread<\/span> thunderstorm development across the state, [&hellip;]<\/p>","protected":false},"author":14,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[4],"tags":[],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/15917"}],"collection":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/users\/14"}],"replies":[{"embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=15917"}],"version-history":[{"count":4,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/15917\/revisions"}],"predecessor-version":[{"id":15930,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/15917\/revisions\/15930"}],"wp:attachment":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=15917"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=15917"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=15917"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}