{"id":1066,"date":"2025-07-20T17:15:11","date_gmt":"2025-07-20T17:15:11","guid":{"rendered":"https:\/\/discussions.weather.arizona.edu\/?p=1066"},"modified":"2025-07-20T17:29:29","modified_gmt":"2025-07-20T17:29:29","slug":"a-nice-day-before-a-stormy-monday-july-20th-2025","status":"publish","type":"post","link":"https:\/\/discussions.weather.arizona.edu\/?p=1066","title":{"rendered":"A nice day before a stormy Monday: July 20th, 2025"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">Yesterday&#8217;s Weather<\/h2>\n\n\n\n<p>The satellite picture below shows the difference between a <a href=\"https:\/\/glossary.ametsoc.org\/wiki\/Mesoscale_convective_complex\">Mesoscale Convective Complex<\/a> (MCC) and <a href=\"https:\/\/glossary.ametsoc.org\/wiki\/Mesoscale_convective_system\">Mesoscale Convective System<\/a> (MCS). The MCC in the Great Plains is about three times the size of the MCS south of Arizona. The other feature is the upper low at the southern end of the Baja, which aided in the development and movement of the MCS.&nbsp;<\/p>\n\n\n\n<figure class=\"wp-block-video\"><video height=\"776\" style=\"aspect-ratio: 978 \/ 776;\" width=\"978\" autoplay controls loop muted src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Recording-2025-07-20-080616.mp4\"><\/video><figcaption class=\"wp-element-caption\">GOES19 long-wave infrared from July 19th 10am to 8am this morning, College of DuPage<\/figcaption><\/figure>\n\n\n\n<p>Most of the rain in the state was in the mountains along the Mogollon Rim, White Mountains, and along the international border. A few of the storms hit the rain buckets in the Bisbee and Fort Huachuca area. The MCS has weakened and the remnant <a href=\"https:\/\/glossary.ametsoc.org\/wiki\/Mesoscale_convective_vortex\">Mesoscale Convective Vortex<\/a> (MCV) can be seen in the cloud cover on the satellite picture below about 30 miles south of the border. A large deck of altocumulus and sprinkles accompanies the MCS.&nbsp;<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"932\" height=\"532\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-082707.png\" alt=\"\" class=\"wp-image-1071\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-082707.png 932w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-082707-300x171.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-082707-768x438.png 768w\" sizes=\"auto, (max-width: 932px) 100vw, 932px\" \/><figcaption class=\"wp-element-caption\">GOES19 lower level water vapor images from July 20th 5am, College of DuPage<\/figcaption><\/figure>\n\n\n\n<p>Finally, the radar below is from the Yuma radar and the signal over the northern Gulf of California is from a gulf surge trapping the radar beam&#8230;not precipitation. Wonderful to be in Puerto Penasco this morning with a temperature of 85<em>\u00b0<\/em>F, dewpoint of 80<em>\u00b0<\/em>F, and a gusty southeast wind at 28mph.\u00a0<\/p>\n\n\n\n<figure class=\"wp-block-video\"><video height=\"584\" style=\"aspect-ratio: 840 \/ 584;\" width=\"840\" autoplay controls loop muted src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Recording-2025-07-20-094354.mp4\"><\/video><figcaption class=\"wp-element-caption\">Radar reflectivity from Yuma 5:30am to 9:20am this morning, College of DuPage<\/figcaption><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Analysis<\/h2>\n\n\n\n<p>The tropical upper tropospheric trough (TUTT) is moving northwest up the Gulf of California with another TUTT is off the coast of Texas. Another TUTT is in the Atlantic well east of Florida.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"697\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-091136-1024x697.png\" alt=\"\" class=\"wp-image-1074\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-091136-1024x697.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-091136-300x204.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-091136-768x523.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-091136.png 1142w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">GOES19 upper level water vapor images from July 20th 9:00am, College of DuPage<\/figcaption><\/figure>\n\n\n\n<p>At 250mb, the TUTT moving northwest up the Gulf of California is weakening. As it moves north it will eventually just be a part of the shear axis that extends to Las Vegas. This shear axis moves very little for the next several days.&nbsp;<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"730\" height=\"755\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-092037.png\" alt=\"\" class=\"wp-image-1075\" style=\"width:630px;height:auto\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-092037.png 730w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-092037-290x300.png 290w\" sizes=\"auto, (max-width: 730px) 100vw, 730px\" \/><\/figure>\n<\/div>\n\n\n<p>The temperatures at 500mb have cooled about 1<em>\u00b0<\/em>C over Arizona and remaining about the same in New Mexico. The ridge is centered over Oklahoma and ridge axis extends west to central New Mexico. The upper-level low over San Diego has not moved from the San Diego area.&nbsp;<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"737\" height=\"752\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-092136.png\" alt=\"\" class=\"wp-image-1077\" style=\"width:639px;height:auto\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-092136.png 737w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-092136-294x300.png 294w\" sizes=\"auto, (max-width: 737px) 100vw, 737px\" \/><\/figure>\n<\/div>\n\n\n<p>At 700mb, the MCV just south of the border is associated with a large area of clouds and some light rain as it moves northward. Winds are light and variable across te southern hallf of Arizona and westerly in New Mexico.&nbsp;<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"738\" height=\"752\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-092153.png\" alt=\"\" class=\"wp-image-1078\" style=\"width:628px;height:auto\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-092153.png 738w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-092153-294x300.png 294w\" sizes=\"auto, (max-width: 738px) 100vw, 738px\" \/><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\">Today<\/h2>\n\n\n\n<p>The cloud cover has extended well north into the eastern two thirds of Arizona. Meanwhile, the Gulf Surge is entering far southwest Arizona this morning with dewpoint temperatures increasing to the 60s\u00b0F.<\/p>\n\n\n\n<figure class=\"wp-block-video\"><video height=\"746\" style=\"aspect-ratio: 1110 \/ 746;\" width=\"1110\" autoplay controls loop muted src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Recording-2025-07-20-093434.mp4\"><\/video><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z 2-meter dewpoint temperautre forecast from 1pm to 2:30am tomorrow morning.<\/figcaption><\/figure>\n\n\n\n<p>Dewpoint temperatures are too low to support convection this afternoon for the rest of the low desert. Strong convection is going to be limited to areas that get decent surface heating, such as southeast Arizona and western New Mexico, as depicted in the forecast radar reflectivity below.\u00a0<\/p>\n\n\n\n<figure class=\"wp-block-video\"><video height=\"748\" style=\"aspect-ratio: 1118 \/ 748;\" width=\"1118\" autoplay controls loop muted src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Recording-2025-07-20-093821.mp4\"><\/video><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z simulated radar reflectivity forecast from 1pm to 2am tomorrow morning.<\/figcaption><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Tomorrow<\/h2>\n\n\n\n<p>The \u201ddown\u201d day today allows the atmosphere to get ready for tomorrow. The gulf surge will resupply the desert with moisture and fewer clouds will allow for more surface heating. Model forecasts show strong convection developing in southeast Arizona in the afternoon and moving northward to the Phoenix area in the evening. The GFS-UA WRF forecast radar is consistent with previous and current HRRR-UA WRF runs now, but will Tucson airport get that much precipitation? Certainly, a day when the flash flood potential is high. <\/p>\n\n\n\n<figure class=\"wp-block-video\"><video height=\"746\" style=\"aspect-ratio: 1112 \/ 746;\" width=\"1112\" autoplay controls loop muted src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Recording-2025-07-20-095137.mp4\"><\/video><\/figure>\n\n\n\n<p>The most recent four UA WRF forecasts that go out to midnight tomorrow night show a spread of 0.11, 0.16, 0.53, 1.2 inches at the Tucson airport (shown below). The flash flood potential is emphasized since all of these totals are possible in different parts of the valley. <\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"336\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-095528-1024x336.png\" alt=\"\" class=\"wp-image-1089\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-095528-1024x336.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-095528-300x98.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-095528-768x252.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-095528-1536x504.png 1536w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-095528.png 1732w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 00Z (left), 12Z (right), total accumulated precipitation forecast through to 5am tomorrow morning.<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"335\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-095734-1024x335.png\" alt=\"\" class=\"wp-image-1090\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-095734-1024x335.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-095734-300x98.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-095734-768x251.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-095734-1536x503.png 1536w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-095734.png 1732w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">GFS-UA WRF 00Z (left), 06Z (right), total accumulated precipitation forecast through to 5am tomorrow morning.<\/figcaption><\/figure>\n\n\n\n<p>Will Phoenix get some? Probably should expect a tenth of an inch or so in the city without the flash flooding potential.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Outlook<\/h2>\n\n\n\n<p>On Tuesday, the focus shifts to northern Arizona with storms forming along the Mogollon Rim into southwest New Mexico, moving northward to Flagstaff and hopefully the Grand Canyon to rain on the fires. We&#8217;ll need to see what the situation is like after the stormy day tomorrow. <\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"337\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-101049-1024x337.png\" alt=\"\" class=\"wp-image-1093\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-101049-1024x337.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-101049-300x99.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-101049-768x252.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-101049-1536x505.png 1536w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2025\/07\/Screenshot-2025-07-20-101049.png 1728w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z (left), GFS-UA WRF 06Z (right), simulated radar reflectivity forecast for Tuesday at 5pm.<\/figcaption><\/figure>\n\n\n\n<p>Discussion written by Pat Holbrook and Patrick Bunn<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Yesterday&#8217;s Weather The satellite picture below shows the difference between a Mesoscale Convective Complex (MCC) and Mesoscale Convective System (MCS). The MCC in the Great Plains is about three times the size of the MCS south of Arizona. The other feature is the upper low at the southern end of the Baja, which aided in &hellip;<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1066","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=\/wp\/v2\/posts\/1066","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1066"}],"version-history":[{"count":18,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=\/wp\/v2\/posts\/1066\/revisions"}],"predecessor-version":[{"id":1100,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=\/wp\/v2\/posts\/1066\/revisions\/1100"}],"wp:attachment":[{"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1066"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1066"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1066"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}