{"id":12777,"date":"2020-08-15T09:16:45","date_gmt":"2020-08-15T15:16:45","guid":{"rendered":"https:\/\/www.coloradofloodthreat.com\/?p=12777"},"modified":"2020-08-16T07:56:05","modified_gmt":"2020-08-16T13:56:05","slug":"ftb-08-15-2020-severe-thunderstorms-and-heavy-rainfall-possible-over-the-eastern-plains","status":"publish","type":"post","link":"https:\/\/archive-coftb.dewberryanalytics.com\/?p=12777","title":{"rendered":"FTB 08-15-2020: Severe Thunderstorms and Heavy Rainfall Possible over the Eastern Plains"},"content":{"rendered":"<p>Issue Date: Saturday, August 15th, 2020<br>\nIssue Time: 9:15AM MDT<\/p>\n<p><em>&mdash; A <strong>LOW<\/strong> flood threat has been issued for the Raton Ridge, Northeast Plains, Southeast Plains, and eastern Palmer Ridge<\/em><\/p>\n<p>The High has shifted west and will start to build northward later today and into tonight, which will start to give the upper flow more of a northerly component over the state. This is especially true over eastern Colorado. Dry air will continue to dominate the majority of the state 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> measured at 0.39 inches in Grand Junction this morning, so this will keep precipitation chances low to nil over western Colorado and most of the high terrains. At the surface, more southeasterly and easterly surface winds are expected over the eastern plains and southern border due to a surface High over the High Plains, which will pull in some higher low-level moisture. Over the Front Range and Urban Corridor, expecting more of a drying, northwesterly surface wind. Paired with more westerly upper flow (also drying), the Front Range and Urban Corridor should stay dry today.<\/p>\n<p><img loading=\"lazy\" class=\"wp-image-12775 size-full aligncenter\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2020\/08\/wv_20200815.png\" alt=\"\" width=\"587\" height=\"440\" srcset=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2020\/08\/wv_20200815.png 587w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2020\/08\/wv_20200815-300x225.png 300w\" sizes=\"(max-width: 587px) 100vw, 587px\"\/><\/p>\n<p>The combination of the surface winds will help set up a convergence boundary further east, which could initiate some <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> this afternoon and evening over the plains. With more northerly steering winds and 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> moving around the ridge helping to spark and maintain <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>, the storms could drop some heavy rainfall as they move south. It also looks like a moderately strong <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> could aid in keeping the <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> going into the late hours of the night. Additionally, stronger upslope flow over the Southeast Mountains, Raton and Palmer Ridge should generate some additional storms, and as the storms move off the mountains, they will be capable of producing some heavier rainfall. A Low flood threat has been issued for the plains as well as over the Raton Ridge where extra convergence will give a better chance for some higher rainfall totals.<\/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.<\/p>\n<p><img loading=\"lazy\" class=\"aligncenter wp-image-12785 size-full\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2020\/08\/FTB_20200815_snap.png\" alt=\"\" width=\"880\" height=\"616\" srcset=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2020\/08\/FTB_20200815_snap.png 880w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2020\/08\/FTB_20200815_snap-300x210.png 300w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2020\/08\/FTB_20200815_snap-768x538.png 768w\" sizes=\"(max-width: 880px) 100vw, 880px\"\/><\/p>\n<h3><strong>Zone-Specific Forecasts:<\/strong><\/h3>\n<h4><strong>Palmer Ridge<\/strong><strong>, <\/strong><strong>Southeast Mountains, Northeast Plains, Southeast Plains, &amp; Raton Ridge:<\/strong><\/h4>\n<p>These areas will have the higher moisture this afternoon and evening, giving them the best chance for some rainfall. <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>, heavier rain will be possible over the Raton Ridge\/Southeast Mountain intersect and slightly east with extra convergence along the ridge. Max 1-hour rain rates up to 1.2 inches will be possible, so a Low flood threat has been issued. Over the Southeast Mountains, rain rates up to 0.25 inches will be possible.<\/p>\n<p><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> over the eastern plains today and tonight could produce max 1-hour rain rates up to 2.75 inches. Some of the guidance is showing <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> staying more <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>, but if the <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> can become upscale tonight (<span class=\"glossaryLink\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;MCS&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;(Stands for: Mesoscale Convective System) A complex of thunderstorms that produces a large, contiguous area of precipitation on the order of 100 km or more in the horizontal scale and normally persist for several hours or more.&lt;\/div&gt;\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>MCS<\/span>), that&rsquo;s when the higher rain rates should be expected. Slightly better chances for these higher rain totals over the Southeast Plains, but if storms can break the <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> over the Northeast Plains, early this evening, rain rates up to 1.9 inches will be possible. There is also a threat for very large hail and damaging <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 with the severe storms that develop. A Low flood threat has been issued.<\/p>\n<p>Primetime: 1PM to 3AM<\/p>\n<h4><strong>Front Range, Urban Corridor,<\/strong> <strong>San Juan Mountains, Central Mountains, Northern Mountains, Southwest Slope, Northwest Slope, Grand Valley<\/strong><strong>, &amp; <\/strong><strong>San Luis Valley: <\/strong><\/h4>\n<p>It should stay mostly dry in the regions today with temperatures rising a couple degrees. There&rsquo;s still some upper-level moisture over the San Juan Mountains (blue in the water vapor imagery), so some high-based storms will be possible further east and south. The main threat will be gusty <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 with only <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> measurable rain possible (under 0.10 inch totals). Air quality will stay low, especially with another fire starting in Grand County yesterday. The more northerly flow aloft will help push some of the smoke further south. With the dry and hot conditions, fire growth is still expected today.<\/p>\n<p>Primetime: 1PM to 8PM<\/p>","protected":false},"excerpt":{"rendered":"<p>Issue Date: Saturday, August 15th, 2020 Issue Time: 9:15AM MDT &mdash; A LOW flood threat has been issued for the Raton Ridge, Northeast Plains, Southeast Plains, and eastern Palmer Ridge The High has shifted west and will start to build northward later today and into tonight, which will start to give the upper flow more [&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\/12777"}],"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=12777"}],"version-history":[{"count":2,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/12777\/revisions"}],"predecessor-version":[{"id":12786,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/12777\/revisions\/12786"}],"wp:attachment":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=12777"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=12777"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=12777"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}