{"id":6188,"date":"2017-08-31T12:16:52","date_gmt":"2017-08-31T18:16:52","guid":{"rendered":"https:\/\/www.coloradofloodthreat.com\/?p=6188"},"modified":"2017-09-04T11:47:55","modified_gmt":"2017-09-04T17:47:55","slug":"fto-08-31-2017-summer-to-leave-with-a-few-storms-and-lots-of-heat-fall-cool-front-to-bring-relief","status":"publish","type":"post","link":"https:\/\/archive-coftb.dewberryanalytics.com\/?p=6188","title":{"rendered":"FTO 08-31-2017: Summer To Leave With A Few Storms And Lots Of Heat; Fall Cool Front To Bring Relief"},"content":{"rendered":"<p>Issue Date: Thursday, August 31, 2017<br>\nIssue Time: 12:20PM MDT<br>\nValid Dates: 9\/1-9\/15<\/p>\n<p><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/08\/threat_timeline-7.png\"><img loading=\"lazy\" class=\"aligncenter wp-image-6189\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/08\/threat_timeline-7.png\" alt=\"\" width=\"880\" height=\"117\"\/><\/a><\/p>\n<p>The afternoon&rsquo;s water vapor imagery, below, shows a disturbance has finally penetrated the previously impressive upper-level ridge. This disturbance will cross Colorado on Friday, bringing <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> shower and storm activity statewide. This is identified as Event #1 in today&rsquo;s 15-day Flood Outlook. However, the ridge will not cede its ground that easily, and will return with a vengeance over the weekend. High temperatures up to 15F above normal are likely statewide with a few lower elevation locations likely to top 100F. For reference, here are the latest dates that long-term Colorado weather stations have recorded a 95F reading:<\/p>\n<ul><li>Alamosa &ndash; July 5 (only happened once),<\/li>\n<li>Colorado Springs &ndash; September 17,<\/li>\n<li>Denver &ndash; September 19,<\/li>\n<li>Pueblo &ndash; September 25 (though 94F has been observed as late as mid-October), and<\/li>\n<li>Grand Junction &ndash; September 18.<\/li>\n<\/ul><p><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/08\/wv_markup-17.png\"><img loading=\"lazy\" class=\"aligncenter wp-image-6191\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/08\/wv_markup-17.png\" alt=\"\" width=\"677\" height=\"392\"\/><\/a><\/p>\n<p>The upper-level ridge re-establishment will be temporary as a strong fall cold front will race southward out of Canada starting Monday. The frontal passage, identified as Event #2, will cause in increase in shower and storm coverage. However, as shown in the forecasted <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;precipitable water&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;The total atmospheric water vapor contained in a vertical column of the atmosphere. It is typically measured in inches, and anomalously (deviation from normal) high values of precipitable water generally correlate to heavy rainfall potential.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>Precipitable Water<\/span> plumes, below, we do not foresee a heavy rainfall threat due to limited moisture and quick storm motion. Thereafter, a slow decrease in available moisture will limit heavy rainfall chances, as well as precipitation in general.<\/p>\n<p><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/08\/gefs_pw-4.png\"><img loading=\"lazy\" class=\"aligncenter wp-image-6190\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/08\/gefs_pw-4.png\" alt=\"\" width=\"750\" height=\"261\"\/><\/a><\/p>\n<p>Below we describe each of the two identified precipitation events in more detail.<\/p>\n<h3><strong>Event #1: Friday (9\/1)<\/strong><\/h3>\n<p>Low-end <span style=\"color: #ff6600;\"><strong>Elevated Flood Threat <\/strong><\/span>as <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;shortwave&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A disturbance in the mid or upper part of the atmosphere which induces upward motion ahead of it.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>shortwave<\/span> moves across Colorado<\/p>\n<p>A <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;shortwave&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A disturbance in the mid or upper part of the atmosphere which induces upward motion ahead of it.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>shortwave<\/span> will continue moving across Colorado on Friday, temporarily increasing rainfall coverage and intensity. Afternoon and evening showers and thunderstorms are expected. Highest coverage will be in the foothills 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>, though some activity will make it farther east especially in the Southeast Plains. With the upper-level support, <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 are also expected across the eastern plains. A severe threat, mainly for large hail, will accompany the <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> heavy rainfall. Max 1-hour rainfall up to 1.1 inch (west) and 1.5 inch (east) can be expected. These rates are right at flood threat intensity and a low-end flood threat is expected 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>. The most vulnerable areas are likely to be burn scars in the Southeast Mountains (Junkins, Beulah Hill, Hayden Pass).<\/p>\n<div style=\"position: relative;\"><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/08\/FTO_20170831_e1.png\"><img loading=\"lazy\" class=\"aligncenter wp-image-6232\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/08\/FTO_20170831_e1.png\" alt=\"\" width=\"880\" height=\"499\"\/><\/a><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/05\/Legend.png\"><img loading=\"lazy\" class=\"alignnone size-full wp-image-230\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/05\/Legend.png\" alt=\"Legend\" width=\"94\" height=\"158\"\/><\/a><\/div>\n<h3><strong>Event #2: Monday (9\/4) through Wednesday (9\/6)<\/strong><\/h3>\n<p><span style=\"color: #0000ff;\"><strong>No Apparent Flood Threat <\/strong><\/span>as front passage likely, but return moisture limited<\/p>\n<p>Guidance is in excellent agreement today regarding the passage of a strong fall-like cool front starting on Monday, 9\/4. An increase in rainfall coverage is expected mainly 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>. However, moisture will be limited, and showers and the main precipitation type. <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 remain a possibility and it is not impossible that a low-end flood threat will develop as the amount of moisture becomes more certain. The best chances of precipitation exceeding 0.5 inches will be in south-central Colorado.<\/p>\n<div style=\"position: relative;\"><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/08\/FTO_20170831_e2.png\"><img loading=\"lazy\" class=\"aligncenter wp-image-6233\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2017\/08\/FTO_20170831_e2.png\" alt=\"\" width=\"880\" height=\"498\"\/><\/a><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/05\/Legend.png\"><img loading=\"lazy\" class=\"alignnone size-full wp-image-230\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/05\/Legend.png\" alt=\"Legend\" width=\"94\" height=\"158\"\/><\/a><\/div>","protected":false},"excerpt":{"rendered":"<p>Issue Date: Thursday, August 31, 2017 Issue Time: 12:20PM MDT Valid Dates: 9\/1-9\/15 The afternoon&rsquo;s water vapor imagery, below, shows a disturbance has finally penetrated the previously impressive upper-level ridge. This disturbance will cross Colorado on Friday, bringing <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> shower and storm activity statewide. This is identified as Event #1 in today&rsquo;s 15-day Flood Outlook. [&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\/6188"}],"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=6188"}],"version-history":[{"count":3,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/6188\/revisions"}],"predecessor-version":[{"id":6234,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/6188\/revisions\/6234"}],"wp:attachment":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6188"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6188"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6188"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}