{"id":721,"date":"2015-06-05T09:23:19","date_gmt":"2015-06-05T15:23:19","guid":{"rendered":"https:\/\/www.coloradofloodthreat.com\/?p=721"},"modified":"2015-06-06T06:29:41","modified_gmt":"2015-06-06T12:29:41","slug":"stp-06-05-2015-widespread-hail-saved-many-from-major-flooding-but-heavy-rainfall-still-observed","status":"publish","type":"post","link":"https:\/\/archive-coftb.dewberryanalytics.com\/?p=721","title":{"rendered":"STP 06-05-2015: Widespread Hail Saved Many From Major Flooding, But Heavy Rainfall Still Observed"},"content":{"rendered":"<p>Issue Date: Friday, May 5th, 2015<br>\nIssue Time: 9:00 AM MDT<\/p>\n<h3>Summary:<\/h3>\n<p>FLOOD WARNINGS\/ADVISORIES CONTINUE FOR PORTIONS OF THE CACHE LA POUDRE RIVER, SOUTH PLATTE RIVER, SOUTH BOULDER CREEK AND LITTLE THOMPSON RIVER.<\/p>\n<p>Very high dewpoints, approaching 60 to 65 F over eastern Colorado fueled a very impressive array of strong and <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;severe thunderstorms&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 thunderstorms<\/span>. Action began along the Palmer <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> in the early afternoon where slow moving, or even stationary thunderstorms first began to cause hail. The first cell, by Elizabeth, CO, caused an <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;outflow boundary&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A surface boundary formed by the horizontal spreading of thunderstorm-cooled air. Outflow boundaries may intersect with each other or with other features (fronts, dry line, low-level jet) and initiate new convection. Brief strong winds are possible with outflow boundaries, and they can also persist for more than 24 hours.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>outflow boundary<\/span> that jump-started a wave of cells lasting into the afternoon, evening and even overnight hours. The following severe weather was observed:<\/p>\n<p><em>Tornadoes<\/em><\/p>\n<p>At least two separate supercells produced tornadoes. One near Simla, and the other near Berthoud. Both were well documented on various social media outlets. There was some reported damage with the Simla storm, and both were certainly quite impressive for Colorado tornado standards.<\/p>\n<p><em>Hail<\/em><\/p>\n<p>Though it is not enjoyable when big hail damages and destroys objects on our property, the incredible amount of hail in yesterday&rsquo;s storms saved many from a much more serious flooding threat. Hail takes time to melt and add to runoff, and can be a huge difference maker in preventing flooding. For example, one <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;CoCoRaHS&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;&amp;lt;strong&amp;gt;Co&amp;lt;\/strong&amp;gt;mmunity &amp;lt;strong&amp;gt;Co&amp;lt;\/strong&amp;gt;llaborative &amp;lt;strong&amp;gt;Ra&amp;lt;\/strong&amp;gt;in, &amp;lt;strong&amp;gt;H&amp;lt;\/strong&amp;gt;ail, and &amp;lt;strong&amp;gt;S&amp;lt;\/strong&amp;gt;now Network, a volunteer network of precipitation observers across the country&amp;lt;\/p&amp;gt;\n&amp;lt;!-- \/wp:paragraph --&amp;gt;&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>CoCoRaHS<\/span> observer noted that about 25% of the total reported rainfall, came from hail! Yesterday&rsquo;s list of hail reports is lengthy and covers many cities and counties in the Palmer <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>, Northeast Plains and Urban Corridor areas. Some of the more impressive reports include:<\/p>\n<ul><li>2.75 inches in Simla, breaking windows and severely damaging cars<\/li>\n<li>2.5 inch in Lyons<\/li>\n<li>1.5 inch in Loveland<\/li>\n<li>Many reports of 0.5 to 1.0 inch hail lasting up to 30 minutes<\/li>\n<\/ul><p><em>Heavy Rainfall<\/em><\/p>\n<p>Thunderstorm rainfall increased in intensity as the evening wore on. Early storms were capable of producing about 1.0 &ndash; 1.25 inches per hour. During the late afternoon and early evening, max 1-hr rainfall rates increased to about 1.7 inches per hour. However, this does not do justice in describing short-term rainfall, which was well observed on the Urban Drainage ALERT network. Several gauges picked up 0.35 to 0.50 inches of rain <em>in 5 minutes<\/em>! Fortunately, most individual storm updrafts were only sustained for 30-45 minutes.<\/p>\n<p>The highest 24-hour rain total came from the tornadic cell near Berthoud where several observers noted over 3 inches of rain. Several other 2 inch + reports were received from Boulder and Larimer counties. Many other locations in the Northeast Plains, Urban Corridor and Palmer Ridge experienced anywhere from 1 to 1.8 inches of rain.<\/p>\n<p>For estimated rainfall in your area, be sure to check out the rainfall map below. <em>NOTE: hail contamination caused severe overestimates in rainfall amounts. For example, radar estimates of the Berthoud storm (Larimer\/Boulder counties) were in the 5-7 inch range, while highest observed values were around 3.5 inches. This is also likely the case with the Simla cell (Elbert County).<\/em><\/p>\n<p>&nbsp;<\/p>\n<div style=\"position: relative;\"><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/06\/06052015_STPImage.png\"><img loading=\"lazy\" class=\"alignnone  wp-image-740\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/06\/06052015_STPImage.png\" alt=\"06052015_STPImage\" width=\"867\" height=\"485\"\/><\/a><br><img loading=\"lazy\" class=\"alignright wp-image-136\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/04\/stormtotalprecip_legend.png\" alt=\"Storm Total Precip Legend\" width=\"470\" height=\"32\"\/><\/div>","protected":false},"excerpt":{"rendered":"<p>Issue Date: Friday, May 5th, 2015 Issue Time: 9:00 AM MDT Summary: FLOOD WARNINGS\/ADVISORIES CONTINUE FOR PORTIONS OF THE CACHE LA POUDRE RIVER, SOUTH PLATTE RIVER, SOUTH BOULDER CREEK AND LITTLE THOMPSON RIVER. Very high dewpoints, approaching 60 to 65 F over eastern Colorado fueled a very impressive array of strong and <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;severe thunderstorms&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 thunderstorms<\/span>. Action [&hellip;]<\/p>","protected":false},"author":4,"featured_media":0,"comment_status":"open","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\/721"}],"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\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=721"}],"version-history":[{"count":6,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/721\/revisions"}],"predecessor-version":[{"id":742,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/721\/revisions\/742"}],"wp:attachment":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=721"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=721"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=721"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}