{"id":13816,"date":"2021-05-15T09:30:17","date_gmt":"2021-05-15T15:30:17","guid":{"rendered":"https:\/\/www.coloradofloodthreat.com\/?p=13816"},"modified":"2021-05-16T07:33:59","modified_gmt":"2021-05-16T13:33:59","slug":"ftb-05-15-2021-severe-weather-threat-continues-east-with-a-low-flood-threat-issued","status":"publish","type":"post","link":"https:\/\/archive-coftb.dewberryanalytics.com\/?p=13816","title":{"rendered":"FTB 05-15-2021: Severe Weather Threat Continues East with a Low Flood Threat Issued"},"content":{"rendered":"<p>Issue Date: Saturday, May 15th, 2021<br>\nIssue Time: 9:30AM MDT<\/p>\n<p><em>&mdash; <\/em><em>A&nbsp;<\/em><strong><em>LOW<\/em><\/strong><em>&nbsp;flood threat has been issued for the Palmer Ridge and portions of the Urban Corridor, Northeast Plains and Southeast Plains<\/em><\/p>\n<p>On tap for today is a very similar pattern to yesterday with a few key differences. Below in the water vapor imagery, you&rsquo;ll see two distinct areas of lift. The orange &ldquo;X&rdquo; over NV and ID is associated with the approaching <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;cutoff low&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;an upper-level low pressure system that has been &amp;quot;cut off&rdquo; from the prevailing winds that steer weather systems; cut-off lows typically become stationary or move very slowly, bringing prolonged periods of unsettled weather&amp;lt;\/p&amp;gt;\n&amp;lt;!-- \/wp:paragraph --&amp;gt;&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>cutoff low<\/span>, while the &ldquo;X&rdquo; over Utah is the <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> that will help spark <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;numerous&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;40-60% areal coverage&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>numerous<\/span> storms across the eastern mountains this afternoon. Moisture remains high to the east and low to the west. <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> at Grand Junction was measured at 0.35 inches with the majority of the moisture around 500mb. This indicates that <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;virga&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Wisps or streaks of precipitation falling out of a cloud that evaporate before reaching the surface. Virga can cause strong, but short-lived, localized winds (dry microburst).&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>virga<\/span> and cloud cover will be prevalent again this afternoon, and the <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> high-based storms that develop over the southern high terrains could again mix down some strong winds to the surface. However, measurable rainfall is not forecast.<\/p>\n<p><img loading=\"lazy\" class=\"aligncenter wp-image-13817\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/wv_20210515.png\" alt=\"\" width=\"650\" height=\"434\" srcset=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/wv_20210515.png 1182w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/wv_20210515-300x201.png 300w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/wv_20210515-768x513.png 768w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/wv_20210515-1024x684.png 1024w\" sizes=\"(max-width: 650px) 100vw, 650px\"\/><\/p>\n<p>Back to the east, moisture has been building over the last couple of days with <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> at Denver going from 0.38 inches 48-hours ago to 0.64 inches this morning. To put that in perspective, that&rsquo;s close to the 90<sup>th<\/sup> percentile for this time of year. Fog and <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> in the upper 40Fs and 50Fs across the adjacent plains are another indication that storms that develop this afternoon and evening will be developing in a moisture-rich environment. Moderate upslope flow (east and southeast surface winds) around 10 mph will continue to hold this moisture in place throughout the day.<\/p>\n<p>Expect storms to fire over the eastern mountains and ridges early this afternoon and move into the adjacent plains where they should pick up in intensity with the pooling moisture, increased <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> and eroding <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>. Slow steering flow from the west and <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;training&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Continuous or repeated rainfall over the same region&nbsp;in a relatively short time span. Training thunderstorms can produce very high rainfall totals and cause flash flooding.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>training<\/span> storms will produce a flood threat over the Palmer Ridge.&nbsp;Except storms to quickly form a line of <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;convection&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Refers to vertical atmospheric motion driven by buoyancy, i.e., warm air is less dense than cool air, and therefore rises. One of the primary drivers of thunderstorm development, especially during monsoon season.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>convection<\/span> as the move into the plains&nbsp;due to the high <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> and moisture environment. More <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> severe storms will be possible today with the main threats being local heavy rainfall, hail and strong <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;outflow&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A cool pool of air that results when a thunderstorm downdraft reaches the surface and spreads horizontally.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>outflow<\/span> winds. A Low flood threat has been issued.<\/p>\n<p>With the <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;low-level jet&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A jet stream that is typically found in the lower 2&ndash;3 km of the atmosphere. At night, this may be referred to as the &amp;quot;nocturnal jet&rdquo; and help sustain storms.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>low-level jet<\/span> kicking back in tonight, some nocturnal <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;convection&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Refers to vertical atmospheric motion driven by buoyancy, i.e., warm air is less dense than cool air, and therefore rises. One of the primary drivers of thunderstorm development, especially during monsoon season.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>convection<\/span> may be possible over the far Southeast Plains. High moisture and slow steering winds means storms will be capable of producing heavy local rainfall. Additionally, this is the same area that received decent rainfall yesterday. Thus, the Low flood threat has been extended eastward.<\/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><img loading=\"lazy\" class=\"aligncenter wp-image-13823\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/FTB_snapshot_20210515.png\" alt=\"\" width=\"880\" height=\"592\" srcset=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/FTB_snapshot_20210515.png 1784w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/FTB_snapshot_20210515-300x202.png 300w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/FTB_snapshot_20210515-768x517.png 768w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/FTB_snapshot_20210515-1024x689.png 1024w\" sizes=\"(max-width: 880px) 100vw, 880px\"\/><\/p>\n<p>&nbsp;<\/p>\n<h3><strong>Zone-Specific Forecasts:<\/strong><\/h3>\n<h4><strong>Front Range, Urban Corridor, Northeast Plains, Southeast Plains, Southeast Mountains, Raton Ridge &amp; Palmer Ridge: <\/strong><\/h4>\n<p>Once again by early afternoon, <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> storms are forecast to develop over the high terrains and elevated Ridges with more <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> activity over&nbsp;the Front Range. Max 1-hour rain rates up to 0.25 inches will be possible over the foothills along with small hail. As storms move into the adjacent plains and develop over the ridges, expect rainfall to intensify due to pooling moisture and higher <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>. Over the Palmer Ridge, slow storm motion and <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;training&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Continuous or repeated rainfall over the same region&nbsp;in a relatively short time span. Training thunderstorms can produce very high rainfall totals and cause flash flooding.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>training<\/span> storms mean 1-2 hour rainfall totals around 1.50 inches will be possible along with hail. This combination of hail and heavy rainfall could cause street, low-land and local stream flooding issues. A Low flood threat has been issued. Brief strong <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;outflow&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A cool pool of air that results when a thunderstorm downdraft reaches the surface and spreads horizontally.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>outflow<\/span> winds and severe hail will also be possible with the stronger storms that develop across the Urban Corridor this afternoon.<\/p>\n<p>As storms move into higher moisture and increased instability over the plains, a line of <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;convection&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Refers to vertical atmospheric motion driven by buoyancy, i.e., warm air is less dense than cool air, and therefore rises. One of the primary drivers of thunderstorm development, especially during monsoon season.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>convection<\/span> is expected to form (southern Northeast Plains and Southeast Plains). These severe storms could produce winds around 60 mph, large hail (2 inches) and local heavy rainfall. Evening and overnight storms will likely continue&nbsp;over the eastern plains with 1-hour rain rates up to 1.75 inches. Thus, the Low flood threat has been extended east for excessive runoff, local stream flooding, road flooding and field ponding.<\/p>\n<p>Primetime: 1PM to 3AM<\/p>\n<h4><strong>Northwest Slope, Northern Mountains, Grand Valley, Central Mountains, San Juan Mountains, Southwest Slope &amp; San Luis Valley:<\/strong><\/h4>\n<p>A few high-based storms are possible over the San Juan and Central Mountains with an increase in cloud cover across all these regions today. Storms that develop south are forecast to produce plenty of <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;virga&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Wisps or streaks of precipitation falling out of a cloud that evaporate before reaching the surface. Virga can cause strong, but short-lived, localized winds (dry microburst).&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>virga<\/span>, which could mix some strong winds down the surface (50 to 60mph gusts) similar to yesterday. Unfortunately, measurable rainfall is not forecast, but a few sprinkles will be possible along and near 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>. Flooding is NOT forecast.<\/p>","protected":false},"excerpt":{"rendered":"<p>Issue Date: Saturday, May 15th, 2021 Issue Time: 9:30AM MDT &mdash; A&nbsp;LOW&nbsp;flood threat has been issued for the Palmer Ridge and portions of the Urban Corridor, Northeast Plains and Southeast Plains On tap for today is a very similar pattern to yesterday with a few key differences. Below in the water vapor imagery, you&rsquo;ll see [&hellip;]<\/p>","protected":false},"author":8,"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\/13816"}],"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=13816"}],"version-history":[{"count":5,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/13816\/revisions"}],"predecessor-version":[{"id":13824,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/13816\/revisions\/13824"}],"wp:attachment":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13816"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=13816"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=13816"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}