{"id":16154,"date":"2021-09-18T09:20:05","date_gmt":"2021-09-18T15:20:05","guid":{"rendered":"https:\/\/www.coloradofloodthreat.com\/?p=16154"},"modified":"2021-09-18T09:20:05","modified_gmt":"2021-09-18T15:20:05","slug":"ftb-09-18-2021-breezy-and-hot-with-scattered-pmovernight-showers-and-weak-storms","status":"publish","type":"post","link":"https:\/\/archive-coftb.dewberryanalytics.com\/?p=16154","title":{"rendered":"FTB 09-18-2021: Breezy And Hot With Scattered PM\/Overnight Showers And Weak Storms"},"content":{"rendered":"<p>Issue Date: Saturday, September 18th, 2021<br>\nIssue Time: 9:20AM MDT<\/p>\n<p><em>&mdash; Flooding is <strong>NOT<\/strong> expected today<\/em><\/p>\n<p>The visible satellite image, below, shows that a vigorous <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> disturbance is located over CA\/NV this morning. Just downstream, deep southerly flow is pumping an impressive moisture surge northward towards the Four Corners region. <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> (<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>) in the southern portion of this plume is well above 1 inch, which is much above normal for mid-September. The main issue in terms of generating rainfall for us here in Colorado is the extremely dry atmosphere overhead. Morning <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 only 0.30 and 0.43 inches in Denver and Grand Junction, respectively. Thus, it will take the majority of the afternoon hours to saturate the atmosphere enough over western Colorado to produce 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> showers and weaker storms. The timing of this also implies that solar heating will not be able to contribute to generate instability, with maximum <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;CAPE&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;(Stands for: Convective Available Potential Energy) CAPE is a measure of the amount of available energy in the atmosphere for convection. Higher values indicate a greater potential for stronger updrafts, thus an increase in the potential for thunderstorms and severe weather.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>CAPE<\/span> of only a few hundred J\/kg expected late today. However, once the atmosphere does become saturated, with a sustained period of lift overhead, <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> showers and an <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> storm are expected to continue over the higher terrain of the Western Slope into the overnight hours. But with limited instability, only modest moisture and fast steering flow, flooding is NOT expected today.<\/p>\n<p>Elsewhere, strong <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;downsloping&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Refers to the winds that blow from higher elevations down towards lower elevations. As air parcels descend, they warm, which often results in rapid warming of areas near the higher terrains. It also promotes lower relative humidity values and stability, which prevents thunderstorm development.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>downsloping<\/span> flow will push temperatures up to 12F above normal 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> today. With this deep <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;boundary layer&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;\/p&amp;gt;\n&amp;lt;!-- \/wp:paragraph --&amp;gt;&amp;lt;br \/&amp;gt;&amp;lt;p&amp;gt;&amp;lt;span style=&amp;quot;color: #ffffff;&amp;quot;&amp;gt;The lower portion of the atmosphere that is directly influenced by the earth&amp;#039;s surface. Primarily, the boundary layer is driven by solar heating during the day and radiational cooling at night.&amp;lt;\/span&amp;gt;&amp;lt;\/p&amp;gt;&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>boundary layer<\/span>, gusty winds are expected during the afternoon hours.<\/p>\n<p><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/vis_markup-1.png\"><img loading=\"lazy\" class=\"size-full wp-image-16156 aligncenter\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/vis_markup-1.png\" alt=\"\" width=\"746\" height=\"503\" srcset=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/vis_markup-1.png 746w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/vis_markup-1-300x202.png 300w\" sizes=\"(max-width: 746px) 100vw, 746px\"\/><\/a><\/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. If there is a threat, hover over the threat areas for more details, and click on burn areas to learn more about them. For Zone-Specific forecasts, scroll below the threat map.<br><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/No_Flood_Threat_2021.png\"><img loading=\"lazy\" class=\" wp-image-13663 aligncenter\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/No_Flood_Threat_2021.png\" alt=\"\" width=\"891\" height=\"668\" srcset=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/No_Flood_Threat_2021.png 768w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/No_Flood_Threat_2021-300x225.png 300w\" sizes=\"(max-width: 891px) 100vw, 891px\"\/><\/a><\/p>\n<h3><strong>Zone-Specific Forecasts:<\/strong><\/h3>\n<h4><strong>Front Range, Northern Mountains, Northwest Slope, Southwest Slope, Grand Valley, Central Mountains, San Juan Mountains, San Luis Valley and Southeast Mountains: <\/strong><\/h4>\n<p>Increasing clouds, warm and breezy with <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> to <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;widely scattered&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;10-25% areal coverage&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>widely scattered<\/span> showers and weaker storms developing late afternoon and persisting into the overnight hours. Max 1-hour rainfall up to 0.5 inches possible, with total precipitation up to 0.7 inches over the higher terrain of the San Juan Mountains and Central Mountains by tomorrow morning. Flooding is NOT expected today. Very gusty winds will be possible with the strongest storms this afternoon and evening.<\/p>\n<p>Primetime: 4PM through 6AM<\/p>\n<h4><strong>Raton Ridge, Southeast Plains, Palmer Ridge, Urban Corridor, Northeast Plains: <\/strong><\/h4>\n<p>Mostly sunny, breezy and hot today with temperatures up to 12F above normal (especially over the Northeast Plains). An <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> shower cannot be ruled out over the higher foothills overnight. However, little in any precipitation is expected. Flooding is NOT expected today.<\/p>","protected":false},"excerpt":{"rendered":"<p>Issue Date: Saturday, September 18th, 2021 Issue Time: 9:20AM MDT &mdash; Flooding is NOT expected today The visible satellite image, below, shows that a vigorous <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> disturbance is located over CA\/NV this morning. Just downstream, deep southerly flow is pumping an impressive moisture surge northward towards the Four Corners region. <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> (<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>) in the [&hellip;]<\/p>","protected":false},"author":4,"featured_media":0,"comment_status":"closed","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\/16154"}],"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=16154"}],"version-history":[{"count":2,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/16154\/revisions"}],"predecessor-version":[{"id":16157,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/16154\/revisions\/16157"}],"wp:attachment":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=16154"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=16154"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=16154"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}