{"id":10714,"date":"2019-09-06T08:39:16","date_gmt":"2019-09-06T14:39:16","guid":{"rendered":"https:\/\/www.coloradofloodthreat.com\/?p=10714"},"modified":"2019-09-07T07:38:29","modified_gmt":"2019-09-07T13:38:29","slug":"ftb-09-06-2019-heavy-post-frontal-rainfall-is-forecast-for-the-eastern-mountains-and-urban-corridors-with-slow-moving-storms","status":"publish","type":"post","link":"https:\/\/archive-coftb.dewberryanalytics.com\/?p=10714","title":{"rendered":"FTB 09-06-2019: Heavy Post-Frontal Rainfall is Forecast for the Eastern Mountains and Urban Corridors with Slow Moving Storms"},"content":{"rendered":"<p>Issue Date: Friday, September 6th, 2019<br>\nIssue Time: 8:40AM MDT<\/p>\n<p><em>&mdash; A&nbsp;<b>MODERATE&nbsp;<\/b>flood threat has been issued for the Front Range, Urban Corridor, Junkins and the Spring Creek burn areas<\/em><\/p>\n<p><em>&mdash; A <strong>LOW <\/strong>flood threat has been issued for the Southeast Mountains, Central Mountains, and eastern portions of the Palmer Ridge, Raton Ridge and Southeast Plains. This threat includes the Hayden Pass burn area.<\/em><\/p>\n<p>Marked in the water vapor imagery below is the aforementioned cold front from yesterday&rsquo;s FTO. This feature is currently pushing south and returning lots of moisture to the atmosphere behind it. This low level moisture return is presenting itself with high <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;dew points&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;The temperature to which a given air parcel must be cooled (at constant pressure and water vapor content) in order for saturation to occur.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>dew points<\/span>, heavy cloud cover and a few light showers over the Northeast Plains, Urban Corridor and Palmer Ridge. <span class=\"glossaryLink\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;PW&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;(Stands for: Precipitable Water) 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\"}]'>PW<\/span> was a whopping 1.06 inches in the Denver sounding this morning! As the cold front pushes south it looks to stall out somewhere south of the Palmer Ridge. Post frontal upslope flow behind the front and slow storm motion will set the stage for the heavy rainfall threat this afternoon. As the next approaching <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> to our west moves eastward, upper flow is forecast to turn more westerly. This will allow storms to spill into the adjacent plains this afternoon and evening with another round of lighter rainfall possible overnight with continuous upslope flow in a moisture rich environment.<\/p>\n<p><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2019\/09\/wv_20190906.png\"><img loading=\"lazy\" class=\"aligncenter wp-image-10715\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2019\/09\/wv_20190906.png\" alt=\"\" width=\"600\" height=\"403\"\/><\/a><\/p>\n<p>As the <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> showers and weak thunderstorms kick off over the higher terrains during the early afternoon, storm movement will be to the west at 10 mph. Trailing storms may allow for higher accumulations, thus the Low flood threat for the eastern mountains. With nearly stationary\/slow moving storms, a Moderate flood threat has been issued for the Spring Creek and Junkins burn areas. The Low flood threat should suffice for the Hayden Pass burn area as the better moisture will be to the west of the scar. Storms may pick up in intensity as they slide off the foothills, so a couple <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> may be possible along the I-25 corridor this afternoon and early evening. Heavy rainfall is possible over the Urban Corridor, so a Moderate flood threat has been issued for the Denver Metro area. Storms are anticipated to weaken as the move east due to a <span class=\"glossaryLink\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;cap&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;The area where a parcel of air has negative buoyancy or sinks. The intensity of the cap is measured by its convective inhibition. If the cap is sufficiently large, it may prevent thunderstorms from forming at all.&lt;\/div&gt;\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>cap<\/span> and decreasing instability, so expect storms to start to disband just east of Highway 71\/104&deg;W. A Moderate\/Low flood threat has been issued for Friday. For rain rates, please see the zone-specific discussions below.<\/p>\n<h3><strong>Today&rsquo;s Flood Threat Map<\/strong><\/h3>\n<p>For more information on today&rsquo;s flood threat, see the map below. For Zone-Specific forecasts, scroll below the map.<\/p>\n<div style=\"position: relative;\"><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2019\/09\/FTB_20190906_snap.png\"><img loading=\"lazy\" class=\"aligncenter wp-image-10725 size-full\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2019\/09\/FTB_20190906_snap.png\" alt=\"\" width=\"880\" height=\"550\"\/><\/a><\/div>\n<div><img loading=\"lazy\" class=\"alignright wp-image-135\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/04\/floodthreat_legend2.png\" alt=\"Flood Threat Legend\" width=\"275\" height=\"71\"\/><\/div>\n<p>&nbsp;<\/p>\n<h3><strong>Zone-Specific Forecasts:<\/strong><\/h3>\n<h4><strong>Front Range, Central Mountains, Southeast Mountains, Raton Ridge, Urban Corridor, Northeast Plains, Palmer Ridge, Southeast Plains:<\/strong><\/h4>\n<p><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> showers and thunderstorms are forecast for this afternoon. Over the mountains, storms will be capable of producing max 1-2 hour rain totals up to 1.40 inches (over the Moderate threat area) and 1.25 inches (south). With slower storm motion, a Moderate flood threat has been issued for the Junkins and Spring Creek burn areas, with the Hayden Pass burn area under the Low threat. Threats this afternoon include <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> of local streams\/creeks, mud flows and debris slides. Those threats are more likely over burn areas if a storm tracks overhead.<\/p>\n<p>A couple <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> may be possible as the storms move into the adjacent plains. Threats from the severe storms include severe hail (1-1.25 inch diameter), gusty winds and heavy, local rainfall. Max 1-hour rain rates up to 1.5 inches will be possible with some <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>, slightly higher storm totals. Thus, the heavy rainfall threats include field ponding, flooding of local streams\/creeks, road flooding and flooding of low-lying areas. A Moderate flood threat has been issued for the Denver Metro area. Another round of light showers and weak thunderstorms is possible overnight with the continuous upslope flow.<\/p>\n<p>Primetime: 1PM to 2AM<\/p>\n<h4><strong>Northwest Slope, Grand Valley, Southwest Slope, Northern Mountains, San Juan Mountains, San Luis Valley:<\/strong><\/h4>\n<p>Unfortunately, the moisture return isn&rsquo;t quite as strong west 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>, but there should be an uptick in storm coverage this afternoon over the high terrains. Expecting another round of <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>, afternoon\/evening showers and weak thunderstorms to kick off during the afternoon. Highest accumulations will again be near 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> and over the San Juan Mountains with up to 0.75 inches possible in the stronger storm cores. 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> moves over the southwest corner early tomorrow morning, which may help spark another round of weak showers over the San Juan and Central Mountains. Accumulations up to 0.25 inches may be possible with these storms. Flooding is not forecast.<\/p>\n<p>Primetime: 1PM to 9AM<\/p>","protected":false},"excerpt":{"rendered":"<p>Issue Date: Friday, September 6th, 2019 Issue Time: 8:40AM MDT &mdash; A&nbsp;MODERATE&nbsp;flood threat has been issued for the Front Range, Urban Corridor, Junkins and the Spring Creek burn areas &mdash; A LOW flood threat has been issued for the Southeast Mountains, Central Mountains, and eastern portions of the Palmer Ridge, Raton Ridge and Southeast Plains. [&hellip;]<\/p>","protected":false},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[6],"tags":[],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/10714"}],"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\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10714"}],"version-history":[{"count":3,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/10714\/revisions"}],"predecessor-version":[{"id":10726,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/10714\/revisions\/10726"}],"wp:attachment":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10714"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10714"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10714"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}