{"id":13946,"date":"2021-05-21T09:45:46","date_gmt":"2021-05-21T15:45:46","guid":{"rendered":"https:\/\/www.coloradofloodthreat.com\/?p=13946"},"modified":"2021-05-21T09:45:46","modified_gmt":"2021-05-21T15:45:46","slug":"ftb-05-21-2021-widespread-precipitation-west-severe-weather-east","status":"publish","type":"post","link":"https:\/\/archive-coftb.dewberryanalytics.com\/?p=13946","title":{"rendered":"FTB 05-21-2021: Widespread Precipitation West &#038; Severe Weather East"},"content":{"rendered":"<p>Issue Date: Friday, May 21st, 2021<br>\nIssue Time: 9:45AM MDT<\/p>\n<p><em>&mdash; Flooding is&nbsp;<\/em><strong><em>NOT&nbsp;<\/em><\/strong><em>expected today<\/em><\/p>\n<p>The upper Low (shown below) will continue to dig in-place today just to our west. A jet on the east side of the Low has is producing southeasterly and southerly winds, which has pulled a nice plume of moisture into western Colorado and eastern Utah. Not surprisingly, <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 has rebounded quite a bit to 0.63 inches with this band of moisture, which is around the 90<sup>th<\/sup> percentile for this time of year. The combination of the two, along with some weak mid-level energy, is helping to produce <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 snow (~9-10K feet) across the western portion of the state this morning. Expecting this precipitation to pick up intensity (north) and coverage throughout the day as mid-level energy continues to move through the flow into the moisture-rich environment. However, a fairly dry surface layer, mild lapse rates, drier spring soils and a mixed precipitation at the highest elevations will limit the heavy rainfall and runoff threat. This should be a nice soaking through this evening with the highest totals by morning expected over the south and southwest facing slopes.<\/p>\n<p><img loading=\"lazy\" class=\"aligncenter wp-image-13947\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/vis_20210521.png\" alt=\"\" width=\"550\" height=\"436\" srcset=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/vis_20210521.png 1036w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/vis_20210521-300x238.png 300w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/vis_20210521-768x609.png 768w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/05\/vis_20210521-1024x812.png 1024w\" sizes=\"(max-width: 550px) 100vw, 550px\"\/><\/p>\n<p>Over the eastern portion of the state, another <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;dryline&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A low-level, small-scale boundary that separates dry air from moist air. Storms develop along it because the dry air (behind the boundary) is less dense than the moisture-rich air (ahead of the boundary). Typically, it advances eastward during the afternoon and retreats westward at night.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>dryline<\/span> is forecast set up over the plains near Highway 59 with lee cyclone development. This means storms that develop on the west side of this line (eastern mountain and ridges) are expected to produce lower rainfall totals with 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>\/wind. Mid-level lift moving through the flow should help pop storms along the <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;dryline&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A low-level, small-scale boundary that separates dry air from moist air. Storms develop along it because the dry air (behind the boundary) is less dense than the moisture-rich air (ahead of the boundary). Typically, it advances eastward during the afternoon and retreats westward at night.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>dryline<\/span> this afternoon in an environment ripe for <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>. The main threat from storms will be large hail, 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 perhaps a tornado before 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> develops. Although there will be plenty of moisture in the area for high rain rates in the storm cores, fast storm motion with the jet overhead, should limit the flood threat. Thus, flooding is NOT forecast this Friday.<\/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=\"wp-image-13436 aligncenter\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/04\/FTB_No_Flood_Threat_2021.png\" alt=\"\" width=\"717\" height=\"538\" srcset=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/04\/FTB_No_Flood_Threat_2021.png 1292w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/04\/FTB_No_Flood_Threat_2021-300x225.png 300w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/04\/FTB_No_Flood_Threat_2021-768x576.png 768w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/04\/FTB_No_Flood_Threat_2021-1024x768.png 1024w\" sizes=\"(max-width: 717px) 100vw, 717px\"\/><\/p>\n<h3><strong>Zone-Specific Forecasts:<\/strong><\/h3>\n<h4><strong>San Juan Mountains, Central Mountains, Northern Mountains, Northwest Slope, Grand Valley &amp; Southwest Slope:<\/strong><\/h4>\n<p>Expect storms to become 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> across these regions by early afternoon as instability and increased lift develop over the area. South, ongoing rainfall and cloud cover will limit the amount of instability that can build, so only mild rainfall rates are forecast. Over the higher elevations, a snow\/rain mix should also help limit the flood threat. <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> precipitation totals up to 2.50 inches will be possible by morning with max 1-hour rain rates up to 0.40 inches.<\/p>\n<p>Further north, some embedded <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 likely this afternoon with heating and mid-level energy moving through the flow. Max 1-hour rain rates up to 0.40 inches will be possible with snow for the highest elevations. <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 totals up to 1 inch will be possible over the western Central Mountains\/Grand Valley higher terrains by morning. Flooding is NOT forecast.<\/p>\n<p>Primetime: Ongoing to Midnight<strong>&nbsp;<\/strong><strong>&nbsp;<\/strong><\/p>\n<h4><strong>Palmer Ridge, Southeast Plains &amp; Northeast Plains:<\/strong><\/h4>\n<p>Severe weather returns to the plains with brisk southerly winds forecast throughout the day with the tightening pressure gradient. Expect storms to develop along a <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;dryline&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A low-level, small-scale boundary that separates dry air from moist air. Storms develop along it because the dry air (behind the boundary) is less dense than the moisture-rich air (ahead of the boundary). Typically, it advances eastward during the afternoon and retreats westward at night.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>dryline<\/span> this afternoon and 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> by this evening. Although local heavy rainfall is possible with the storm cores, storm motion should be quick enough to limit the flood threat. Max 1-hour rain rates up to 1.50 inches (north) and 1.25 inches (south) will be possible. Large hail, 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 a couple tornadoes are also possible with the severe storms that develop. Flooding is NOT forecast.<\/p>\n<p>Primetime: 4PM to Midnight<\/p>\n<h4><strong>Raton Ridge, Front Range, San Luis Valley, Southeast Mountains, &amp; Urban Corridor:<\/strong><\/h4>\n<p>Another warm day is ahead with breezy conditions. <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> storms may develop over the Front Range and northern Southeast Mountains favoring areas along 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>. With surface moisture decreasing and strong upper-level steering flow, storms that are able to pop will have limited rainfall potential. <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> totals up to 0.20 inches (north) will be possible with lower totals further south. As storms move off the high terrains, high cloud bases mean the main threat will be wind with the <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> producing storms. Flooding is NOT forecast.<\/p>\n<p>Primetime: 12:30PM to 8PM<\/p>\n<p><strong>&nbsp;<\/strong><\/p>","protected":false},"excerpt":{"rendered":"<p>Issue Date: Friday, May 21st, 2021 Issue Time: 9:45AM MDT &mdash; Flooding is&nbsp;NOT&nbsp;expected today The upper Low (shown below) will continue to dig in-place today just to our west. A jet on the east side of the Low has is producing southeasterly and southerly winds, which has pulled a nice plume of moisture into western [&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\/13946"}],"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=13946"}],"version-history":[{"count":2,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/13946\/revisions"}],"predecessor-version":[{"id":13949,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/13946\/revisions\/13949"}],"wp:attachment":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13946"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=13946"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=13946"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}