{"id":4636,"date":"2017-05-25T15:03:05","date_gmt":"2017-05-25T21:03:05","guid":{"rendered":"https:\/\/www.coloradofloodthreat.com\/?p=4636"},"modified":"2017-05-29T10:03:39","modified_gmt":"2017-05-29T16:03:39","slug":"fto-05-25-2017-two-elevated-flood-threat-events-then-snow-melt-begins-in-earnest-later-next-week","status":"publish","type":"post","link":"https:\/\/archive-coftb.dewberryanalytics.com\/?p=4636","title":{"rendered":"FTO 05-25-2017: Two Elevated Flood Threat Events, Then Snow Melt Begins In Earnest Later Next Week"},"content":{"rendered":"<p>Issue Date: Thursday, May 25th, 2017<br>\nIssue Time: 3:00PM<br>\nValid Dates: 5\/26 &ndash; 6\/9<\/p>\n<p><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/05\/threat_timeline-4.png\"><img loading=\"lazy\" class=\"aligncenter wp-image-4637\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/05\/threat_timeline-4.png\" alt=\"\" width=\"880\" height=\"104\"\/><\/a><\/p>\n<p>In today&rsquo;s eastern Pacific water vapor imagery, shown below, we get a glimpse at many of the features that will be affecting Colorado&rsquo;s weather over the next 15 days. The first feature is the disturbance located over southern Canada with a <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> draped southwest across Colorado. This will provide a few days of elevated flood threat conditions mainly for <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;isolated&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;less than 10% areal coverage&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>isolated<\/span> <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> (along with severe weather) in eastern Colorado. Looking slightly farther west we see a ridge of modest strength located just offshore of North America. This ridge will attempt to bulge into Colorado but should be help back from doing so over the next week or so, in part due to the disturbance that will be causing our second precipitation event (Event #2) next week. Thereafter, the ridge will appear to regain the upper hand which will provide an extended warm period for most of the state. With a healthy snowpack still in place, we have labeled Event #3 as a string of days where substantial melt is expected.<\/p>\n<p><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/05\/wv_markup-13.png\"><img loading=\"lazy\" class=\"aligncenter wp-image-4638\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/05\/wv_markup-13.png\" alt=\"\" width=\"700\" height=\"427\"\/><\/a><\/p>\n<p>Below we describe each Event in more detail.<\/p>\n<h3><strong>Event #1: Friday (5\/26) through Sunday (5\/28) <\/strong><\/h3>\n<p><span style=\"color: #ff6600;\"><strong>Elevated Flood Threat<\/strong><\/span> through Saturday for eastern Colorado, followed by more steady rain<\/p>\n<p>The upper-level <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> responsible for today&rsquo;s (Thursday) shower and storm activity will actually generate a daily low-level circulation east of the <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;Continental 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\"}]'>Continental Divide<\/span>. Friday&rsquo;s system will have the best chances of generating <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> heavy rainfall. We anticipate 1-2 waves of organized shower and storm activity beginning late morning over the higher terrain, then moving east into the Plains. Very heavy rainfall will be possible especially towards the Kansas border, with max 1-hour rain rates up to 2.4 inches and 3-hour rain rates up to 2.9 inches. <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;isolated&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;less than 10% areal coverage&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>Isolated<\/span> <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> will accompany the strongest storms, and street flooding will be likely for low-lying municipal areas. In addition to the heavy rainfall, severe weather in the form of large hail (up to 2.5 inches), damaging winds (up to 75mph) and <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;isolated&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;less than 10% areal coverage&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>isolated<\/span> tornadoes will be possible. Heading into Saturday, cooler, more <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;stable&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 atmosphere is considered stable if it resists air attempting to rise; the opposite of unstable&amp;lt;\/p&amp;gt;\n&amp;lt;!-- \/wp:paragraph --&amp;gt;&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>stable<\/span> air will slowly overtake northern Colorado, but instability will still be present in the southeast. At least one round of showers and storms will develop across the Southeast Plains with 1-hour rain rates up to 1.6 inches, causing <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;isolated&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;less than 10% areal coverage&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>isolated<\/span> <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>. By Sunday, cooler air will overtake most of the state, but residual moisture will allow for upslope shower and maybe a weak thunderstorm. However, flooding is not expected on Sunday.<\/p>\n<p><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/05\/FTO_20170525_e1.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-4687\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/05\/FTO_20170525_e1.png\" alt=\"\" width=\"892\" height=\"505\"\/><\/a><\/p>\n<div id=\"FTOlegend\" align=\"right\"><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/05\/Legend.png\"><img loading=\"lazy\" class=\"alignright wp-image-230 size-full\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/05\/Legend.png\" alt=\"Legend\" width=\"94\" height=\"158\"\/><\/a><\/div>\n<p>&nbsp;<\/p>\n<h3><strong>Event #2: Wednesday (5\/31) through Thursday (6\/1)<\/strong><\/h3>\n<p><span style=\"color: #ff6600;\"><strong>Elevated Flood Threat <\/strong><\/span>as disturbance approaches Colorado from the southwest<\/p>\n<p>After a short break following Event #1, a southern stream disturbance will penetrate through the west coast ridge and will affect mainly southern Colorado beginning Wednesday 5\/31. The strength of the atmospheric dynamics are uncertain right now, but it does appear that there will be enough moisture for at least <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;isolated&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;less than 10% areal coverage&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>isolated<\/span> thunderstorms capable of producing heavy rainfall. The areas most likely to be impacted are the San Juans, stretching east into southeast Colorado. Up to 1.5 inches of rainfall will be possible, based on current guidance.<br><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/05\/FTO_20170525_e2.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-4687\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/05\/FTO_20170525_e2.png\" alt=\"\" width=\"892\" height=\"505\"\/><\/a><\/p>\n<div id=\"FTOlegend\" align=\"right\"><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/05\/Legend.png\"><img loading=\"lazy\" class=\"alignright wp-image-230 size-full\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/05\/Legend.png\" alt=\"Legend\" width=\"94\" height=\"158\"\/><\/a><\/div>\n<h3>Event #3: Sunday (6\/4) through Wednesday (6\/7)<\/h3>\n<p>Snow melt to accelerate but <strong><span style=\"color: #0000ff;\">No Anticipated Flood Threat<\/span><\/strong> at this time<\/p>\n<p>A high-pressure ridge will begin to control the western North American circulation starting later next week. High temperatures will climb to above normal levels for a multi-day period, allowing for high-elevation snow melt to begin in earnest. Locations below 9,000 feet have already generally melted out (with some exceptions due to the recent late season snowstorm). However, a solid snowpack remains above 9,000 feet. At this time, only modestly above average temperatures are expected, thus we do not expect major flood-related issues. However, this will need to be monitored. The basins that are most prone to snow-melt related high flows will be the South Platte and San Juan region, as shown in the <span class=\"glossaryLink\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;SWE&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;S&amp;lt;\/strong&amp;gt;now &amp;lt;strong&amp;gt;W&amp;lt;\/strong&amp;gt;ater &amp;lt;strong&amp;gt;E&amp;lt;\/strong&amp;gt;quivalent, the liquid water content of snowpack&amp;lt;\/p&amp;gt;\n&amp;lt;!-- \/wp:paragraph --&amp;gt;&lt;\/div&gt;\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>SWE<\/span> charts below. Nonetheless, other <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;isolated&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;less than 10% areal coverage&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>isolated<\/span> locations with a high snowpack may be vulnerable to high flows as well. Time to book those rafting trips, if you have not already done so!<br><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/05\/swe_2panel.png\"><img loading=\"lazy\" class=\"aligncenter wp-image-4639\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/05\/swe_2panel.png\" alt=\"\" width=\"880\" height=\"300\"\/><\/a><\/p>","protected":false},"excerpt":{"rendered":"<p>Issue Date: Thursday, May 25th, 2017 Issue Time: 3:00PM Valid Dates: 5\/26 &ndash; 6\/9 In today&rsquo;s eastern Pacific water vapor imagery, shown below, we get a glimpse at many of the features that will be affecting Colorado&rsquo;s weather over the next 15 days. The first feature is the disturbance located over southern Canada with a [&hellip;]<\/p>","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[3],"tags":[],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/4636"}],"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=4636"}],"version-history":[{"count":3,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/4636\/revisions"}],"predecessor-version":[{"id":4689,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/4636\/revisions\/4689"}],"wp:attachment":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4636"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4636"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4636"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}