{"id":1333,"date":"2015-07-20T10:17:21","date_gmt":"2015-07-20T16:17:21","guid":{"rendered":"https:\/\/www.coloradofloodthreat.com\/?p=1333"},"modified":"2015-07-21T06:35:50","modified_gmt":"2015-07-21T12:35:50","slug":"ftb-07-20-2015-low-to-moderate-flood-threat-as-subtropical-moisture-remains","status":"publish","type":"post","link":"https:\/\/archive-coftb.dewberryanalytics.com\/?p=1333","title":{"rendered":"FTB 07-20-2015: Low-to-Moderate Flood Threat as Subtropical Moisture Remains"},"content":{"rendered":"<p>Issue Date: 7\/20\/2015<br>\nIssue Time: 10:07 AM<\/p>\n<p><em>A MODERATE FLOOD THREAT IS ISSUED FOR PORTIONS OF THE RATON RIDGE AND SOUTHEAST PLAINS.<\/em><\/p>\n<p><em>A LOW FLOOD THREAT IS ISSUED FOR PORTIONS OF THE CENTRAL MOUNTAINS, SAN JUAN MOUNTAINS, SOUTHWEST SLOPE, FRONT RANGE, SOUTHEAST MOUNTAINS, RATON RIDGE, AND SOUTHEAST PLAINS.<\/em><\/p>\n<p>Colorado remains under the influence of mid-level subtropical moisture as the high pressure ridge remains in a favorable position over the south-central US. For locations experiencing greater surface moisture the result is higher <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> values. Low-level moisture decreases, on average, from south to north, and this is easily seen in the IPW graph below; Pueblo currently sits at 1.2 inches, Colorado Springs and Grand Junction between 0.8 and 1.0 inch, and Boulder around 0.6 inches. This deeper moisture is important when it comes to today&rsquo;s thunderstorm chances and subsequent flood threat.<\/p>\n<p><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/07\/IPW_07202015.png\"><img loading=\"lazy\" class=\"  wp-image-1334 aligncenter\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/07\/IPW_07202015.png\" alt=\"IPW_07202015\" width=\"513\" height=\"220\"\/><\/a><\/p>\n<p>The mountains will experience the best coverage of showers and thunderstorms today, especially along and south of I-70, as orographic influences combine with daytime heating and make use of the subtropical moisture available. Locally heavy rainfall will be possible, but storm motions will help limit the flood threat somewhat. An influx of moisture from the southwest will occur overnight, likely keeping showers and a thunderstorm or two around through tomorrow morning.<\/p>\n<p>For areas east of the mountains, the probability of thunderstorms decreases from west to east. The Urban Corridor and Palmer Ridge will hold the chance for <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> weak thunderstorms this afternoon and evening, but they will rely on <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;outflow boundaries&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A surface boundary formed by the horizontal spreading of thunderstorm-cooled air. Outflow boundaries may intersect with each other or with other features (fronts, dry line, low-level jet) and initiate new convection. Brief strong winds are possible with outflow boundaries, and they can also persist for more than 24 hours.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>outflow boundaries<\/span> from mountain <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> to develop. The Northeast Plains will stay dry, except for a stray weak shower\/thunderstorm near the Urban Corridor, as the environment will stay <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;capped&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\"}]'>capped<\/span> due to weak subsidence, warm mid-level temperatures and drying low-levels. The most active locations east of the mountains will be the Raton Ridge and southern extents of the Southeast Plains, thanks to more available moisture and the presence of a weak surface boundary that will stall near the CO\/NM border. <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> thunderstorms will be likely across the Raton Ridge near the interface with the Southeast Mountains, with 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> activity across the remainder of the Raton Ridge and the Southeast Plains.<\/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 (hover over threat areas for more details). For Zone-Specific forecasts, jump below the map.<\/p>\n<div style=\"position: relative;\"><a href=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/07\/20150720_MFT.png\"><img loading=\"lazy\" class=\"alignnone size-full wp-image-1341\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/07\/20150720_MFT.png\" alt=\"20150720_MFT\" width=\"890\" height=\"499\"\/><\/a><\/div>\n<div><img loading=\"lazy\" class=\"alignright wp-image-135\" src=\"https:\/\/archive-coftb.dewberryanalytics.com\/wp-content\/uploads\/2015\/04\/floodthreat_legend2.png\" alt=\"Flood Threat Legend\" width=\"275\" height=\"71\"\/><\/div>\n<h3><\/h3>\n<h3><strong>Zone-Specific Forecasts<\/strong><\/h3>\n<h4><strong>Urban Corridor, Palmer Ridge, and Northeast Plains:<\/strong><\/h4>\n<p>Mostly sunny and warm will be the main story today, with only a couple <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>, weak showers\/thunderstorms possible this afternoon and evening, with the best relative chance across the Urban Corridor. Flooding issues are not expected as storm motions and low-to-moderate rain rates will not be enough to warrant concern. Maximum rain rates will be 0.4-1.0 inches\/hour.<\/p>\n<p>Timing: 1 PM &ndash; 9 PM, with one or two showers\/thunderstorms possible through 1 AM thanks to <span class=\"glossaryLink\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;outflow boundaries&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A surface boundary formed by the horizontal spreading of thunderstorm-cooled air. Outflow boundaries may intersect with each other or with other features (fronts, dry line, low-level jet) and initiate new convection. Brief strong winds are possible with outflow boundaries, and they can also persist for more than 24 hours.&lt;\/div&gt;\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'>outflow boundaries<\/span> from mountain <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>.<\/p>\n<h4><strong>Southeast Plains and Raton Ridge:<\/strong><\/h4>\n<p>Mostly sunny and dry for most, with <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 thunderstorms south of Highway 50, near the interface with the Southeast Mountains, becoming 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> to the east. Maximum rain rates will be 1.2-2.0 inches\/hour.<\/p>\n<p>Timing: 1 PM &ndash; Midnight, with a few <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\/thunderstorms continuing into tomorrow morning as moisture increases from the southwest with the arrival of the next disturbance.<\/p>\n<h4><strong>Front Range, Northern Mountains, Northwest Slope, Grand Valley, Central Mountains, Southeast Mountains, San Luis Valley, Southwest Slope, and San Juan Mountains:<\/strong><\/h4>\n<p>Partly sunny with temperatures slightly below average will be the name of the game today as <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 weak thunderstorms are expected north of I-70, becoming <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>\/more <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> south of I-70. The further south, the deeper the moisture will be, and thus, the higher the maximum rain rates. Let&rsquo;s break it down:<\/p>\n<p>Northern Mountains, Northwest Slope, and Grand Valley: 0.4-0.8 inches\/hour<br>\nCentral Mountains and Front Range: 0.6-1.1 inches\/hour<br>\nSan Juan Mountains, Southwest Slope, San Juan Valley, and Southeast Mountains: 0.8-1.4 inches\/hour<\/p>\n<p>Timing: 11 AM &ndash; 8 PM, with ongoing showers and thunderstorms expected into tomorrow morning for southern zones (Southwest Slope, San Juan Mountains, and San Luis Valley) as moisture increases from the south\/southwest with the arrival of the next disturbance.<\/p>","protected":false},"excerpt":{"rendered":"<p>Issue Date: 7\/20\/2015 Issue Time: 10:07 AM A MODERATE FLOOD THREAT IS ISSUED FOR PORTIONS OF THE RATON RIDGE AND SOUTHEAST PLAINS. A LOW FLOOD THREAT IS ISSUED FOR PORTIONS OF THE CENTRAL MOUNTAINS, SAN JUAN MOUNTAINS, SOUTHWEST SLOPE, FRONT RANGE, SOUTHEAST MOUNTAINS, RATON RIDGE, AND SOUTHEAST PLAINS. Colorado remains under the influence of mid-level [&hellip;]<\/p>","protected":false},"author":1,"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\/1333"}],"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\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1333"}],"version-history":[{"count":2,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/1333\/revisions"}],"predecessor-version":[{"id":1343,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=\/wp\/v2\/posts\/1333\/revisions\/1343"}],"wp:attachment":[{"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1333"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1333"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/archive-coftb.dewberryanalytics.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1333"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}