{"id":15871,"date":"2021-09-02T09:51:02","date_gmt":"2021-09-02T15:51:02","guid":{"rendered":"https:\/\/www.coloradofloodthreat.com\/?p=15871"},"modified":"2021-09-03T07:51:09","modified_gmt":"2021-09-03T13:51:09","slug":"ftb-09-02-2021-flood-threat-shifts-into-eastern-colorado","status":"publish","type":"post","link":"https:\/\/archive-coftb.dewberryanalytics.com\/?p=15871","title":{"rendered":"FTB 09-02-2021: Flood Threat Shifts Into Eastern Colorado"},"content":{"rendered":"<p>Issue Date: Thursday, September 2nd, 2021<br>\nIssue Time: 9:50AM MDT<\/p>\n<p><em>&mdash; <\/em><em>A&nbsp;<\/em><strong><em>LOW&nbsp;<\/em><\/strong><em>flood threat has been issued for the southern Front Range, southern Urban Corridor, Palmer Ridge, northern Southeast Plains and southern Northeast Plains<\/em><br><em>&mdash; <span style=\"color: #ff0000;\">Possible PM update may be issued<\/span><\/em><\/p>\n<p>Southwesterly flow aloft continues across the state this morning with the main axis of precipitation to our east. There are still some ongoing, <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 over the western portion of the state and Northern Mountains, which indicates a little mid-level lift in the area in an otherwise subsidence promoting environment. Flow aloft by midday will become more westerly as another <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> drops in from the Pacific Northwest (orange &ldquo;X&rdquo;). This will begin to pull in a drier air mass across western Colorado, which will start to drop <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> values and decrease the chances for rainfall over the next several days. However, there should still be enough residual moisture and mid-level lift for a 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>, mountain storms this afternoon and evening favoring areas south of I-70. So, expect the current showers to expand a little bit in coverage and intensity as they meander west throughout the day. A couple evening storms may also be possible over the Grand Valley and Northwest Slope, but with instability dropping off rapidly with the sun setting, storms should dissipate rather quickly. With the smaller storm cores and lower-end rainfall rates today, flooding is not expected over this area.<\/p>\n<p><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 has risen to just under 1 inch over the last 24-hours, and this moisture is forecast to hang on through tomorrow night. With mid-level energy approaching from the west, <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 return to the area, and more so than yesterday, they are expected to spill into the southern Urban Corridor. Best coverage of showers and storms will be over the southern Front Range and Palmer Ridge where there will be a bit better convergence and mid-level lift. Slower steering flows 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 may cause some localized flooding issues with the above-average moisture over the Palmer Ridge, if a couple stronger thunderstorms can develop. There is also the possibility of some overnight storms in this area with an uptick in lift forecast. A nice theta-e gradient may work its way into the eastern plains, and if storms generate along this feature, heavy rainfall should be expected. For these reasons, a LOW flood threat has been issued. Should this threat for overnight storms drop off by this afternoon, a PM update will be issued.<\/p>\n<p><img loading=\"lazy\" class=\"aligncenter wp-image-15877\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/wv_20210902.png\" alt=\"\" width=\"600\" height=\"434\" srcset=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/wv_20210902.png 1350w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/wv_20210902-300x217.png 300w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/wv_20210902-768x555.png 768w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/wv_20210902-1024x740.png 1024w\" sizes=\"(max-width: 600px) 100vw, 600px\"\/><\/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-15896\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/FTB_20210902_snap.png\" alt=\"\" width=\"880\" height=\"596\" srcset=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/FTB_20210902_snap.png 1784w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/FTB_20210902_snap-300x203.png 300w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/FTB_20210902_snap-768x520.png 768w, https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2021\/09\/FTB_20210902_snap-1024x693.png 1024w\" sizes=\"(max-width: 880px) 100vw, 880px\"\/><\/p>\n<h3><strong>Zone-Specific Forecasts:<\/strong><strong>&nbsp;<\/strong><\/h3>\n<h4><strong>Southeast Plains, Northeast Plains, Southeast Mountains, Front Range, Urban Corridor, Palmer Ridge &amp; Raton Ridge:<\/strong><\/h4>\n<p>Afternoon and evening storms are expected over the central, eastern Colorado as the mid-level lift works its way over from the west. Subsidence elsewhere should keep storm chances limited over the northern\/southern mountains. In addition to <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> and slow-moving storms this afternoon\/evening, some storms will be possible over the Palmer Ridge and eastern plains overnight. Rainfall that develops along a theta-e axis (front) overnight may also be capable of producing heavy rainfall. Max 1-hour rain rates up to 1.75 inches and storm totals up to 3 inches will be possible. Therefore, a LOW flood threat has been issued for possible road flooding, bankfull conditions of local streams\/creeks, mud flows\/debris slides (west) and field ponding under the more robust&nbsp;storm cores. A couple thunderstorms may also be capable of producing small 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 dangerous lightning. Note that this is an overnight threat.<br>\nPrimetime: 12:30PM to 6AM<\/p>\n<h4><strong>San Juan Mountains, Northern Mountains, Central Mountains, Southwest Slope, San Luis Valley, Grand Valley &amp; Northwest Slope:<\/strong><\/h4>\n<p>More <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 today over the higher terrains mostly south of I-70. Without much instability being able to build, rainfall rates should be on the lower end and accumulations should be gradual enough, and over a small enough area, to avoid flooding issues. A quick 0.50 inches of rain may be able to fall over a 30-minute period if a couple stronger storms can develop. <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> morning totals up to 1 inch will be possible over the higher terrains of the Northwest Slope (south), Grand Valley and San Juan Mountains, but flooding is NOT forecast today.<br>\nPrimetime: Ongoing to 10PM<\/p>","protected":false},"excerpt":{"rendered":"<p>Issue Date: Thursday, September 2nd, 2021 Issue Time: 9:50AM MDT &mdash; A&nbsp;LOW&nbsp;flood threat has been issued for the southern Front Range, southern Urban Corridor, Palmer Ridge, northern Southeast Plains and southern Northeast Plains &mdash; Possible PM update may be issued Southwesterly flow aloft continues across the state this morning with the main axis of precipitation [&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\/15871"}],"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=15871"}],"version-history":[{"count":4,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/15871\/revisions"}],"predecessor-version":[{"id":15897,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/15871\/revisions\/15897"}],"wp:attachment":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=15871"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=15871"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=15871"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}