{"id":4744,"date":"2026-08-20T17:41:43","date_gmt":"2026-08-20T17:41:43","guid":{"rendered":"https:\/\/discussions.weather.arizona.edu\/?p=4744"},"modified":"2026-08-20T18:32:34","modified_gmt":"2026-08-20T18:32:34","slug":"august-20th-2026-some-isolated-storms-are-forecast-over-the-mountains-today-and-tomorrow-but-monsoon-returns-to-low-grade-after-the-activity-from-last-night","status":"publish","type":"post","link":"https:\/\/discussions.weather.arizona.edu\/?p=4744","title":{"rendered":"August 20th, 2026: Some isolated storms are forecast over\u00a0the mountains today and tomorrow, but monsoon returns to low grade after the activity\u00a0from last night."},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">Summary<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Water vapor satellite imagery shows three Tropical Upper Tropospheric Troughs (TUTT); one moving off the Baja Peninsula, another west of Brownsville, and another in central Florida. The monsoon high is positioned over west-central Arizona, influencing the movement of these troughs and the overall flow pattern. A remnant mesoscale convective vortex (MCV) from last night&#8217;s storms near Phoenix is dissipating near Yuma, while surface dewpoints remain steady due to persistent Gulf Surge moisture.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Today, most thunderstorms are expected from the Mogollon Rim into northern Arizona and New Mexico, with isolated storms in southeast Arizona producing limited rainfall. Tomorrow will bring scattered showers and thunderstorms, mainly away from the Phoenix and Tucson valleys, with no significant severe weather expected. The outlook for the weekend shows a decrease in monsoon activity, with only light rainfall anticipated across the region.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Yesterday&#8217;s Weather<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Yesterday, thunderstorms moved into Tucson further north than numerical weather prediction model forecasts predicted, riding strong outflows. The fastest&nbsp;wind speed&nbsp;reported at&nbsp;Tucson International Airport&nbsp;was&nbsp;a gust of 63 mph. The heaviest rain fell along the Sabino\/Bear Canyon washes as a thunderstorm developed there around 5:20 pm, and because of training, the storm stayed in the same location for over an hour, producing 1.85&#8243; of rain. A swift water rescue occurred south of Tucson where additional&nbsp;heavy rain&nbsp;fell.&nbsp;<\/p>\n\n\n\n<figure class=\"wp-block-video aligncenter\"><video height=\"822\" style=\"aspect-ratio: 1698 \/ 822;\" width=\"1698\" autoplay controls loop muted src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/20260820-1617-24.0545661.mp4\" playsinline><\/video><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z simulated radar reflectivity forecast (left) and corresponding observed radar reflectivity MRMS (right) for August 19th at 2 pm to August 20th at 6 am.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">In the&nbsp;Phoenix&nbsp;area,&nbsp;outflows from thunderstorms&nbsp;to its south reached Mesa-Gateway Airport at 9:19 pm with a wind gust of 56 mph and visibility dropping to a half mile from blowing dust. High winds continued at the airport, with a maximum of 63 mph at 9:48 pm. Not to be outdone, Sky Harbor had&nbsp;a 68 mph wind gust at 10:00 pm. The NWS issued a dust storm warning and&nbsp;reported:&nbsp;&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em>\u201cAt 9:14 PM MST, a wall of dust was along a line extending from Kings<\/em>&nbsp;<em>Ranch to near Queen Creek to near Chandler Heights, moving<\/em>&nbsp;<em>northwest at 30 mph.\u201d<\/em>&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This sounds like a haboob,&nbsp;but since it was dark by then, the pictures of the haboob were not as good as if it had occurred during the day.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The infrared satellite picture taken at 10:15 pm shows a Mesoscale&nbsp;Convective&nbsp;System centered over Pinal and Maricopa counties moving slowly west.&nbsp;<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"662\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-156-1024x662.png\" alt=\"\" class=\"wp-image-4748\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-156-1024x662.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-156-300x194.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-156-768x497.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-156.png 1245w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">GOES-19 infrared satellite imagery from August 19th at 10:16 pm, College of DuPage.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">In Pima County, the heaviest rain was south of Tucson; moving northwest, the rainfall totals were lighter. Davis-Monthan AFB received 1.11&#8243; while Marana and Pinal Air Park only received 0.01&#8243;.&nbsp;<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"797\" height=\"752\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-157.png\" alt=\"\" class=\"wp-image-4751\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-157.png 797w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-157-300x283.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-157-768x725.png 768w\" sizes=\"auto, (max-width: 797px) 100vw, 797px\" \/><figcaption class=\"wp-element-caption\">24-hour precipitation totals from Pima County Regional Flood Control District gauges, <a href=\"https:\/\/alertmap.rfcd.pima.gov\/gmap\/gmap.html\">Alert Map<\/a>.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">The heaviest rain in the Phoenix area was east of I-10\/17, with the storms building&nbsp;and&nbsp;moving in from the southeast on strong outflows. Further west, the precipitation amounts&nbsp;were&nbsp;lighter.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"847\" height=\"787\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-158.png\" alt=\"\" class=\"wp-image-4752\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-158.png 847w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-158-300x279.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-158-768x714.png 768w\" sizes=\"auto, (max-width: 847px) 100vw, 847px\" \/><figcaption class=\"wp-element-caption\">24-hour precipitation totals from Maricopa County Regional Flood Control District gauges, <a href=\"https:\/\/alert.fcd.maricopa.gov\/alert\/Google\/v3\/gmap.html\">Alert Map<\/a>.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">The HRRR-UA WRF 12Z 24-hour accumulated precipitation forecast (left) and corresponding observed precipitation from MRMS (right) are shown below.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"338\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-159-1024x338.png\" alt=\"\" class=\"wp-image-4753\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-159-1024x338.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-159-300x99.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-159-768x253.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-159-1536x507.png 1536w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-159.png 1730w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z 24-hour accumulated precipitation forecast (left) and corresponding observed precipitation from MRMS (right) for August 19th.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">The 15Z forecast (left) and the 18Z forecast (right) are also shown. Overall, although the precipitation pattern was forecast correctly, the amount was underestimated.&nbsp;<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"335\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-160-1024x335.png\" alt=\"\" class=\"wp-image-4755\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-160-1024x335.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-160-300x98.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-160-768x251.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-160-1536x502.png 1536w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-160.png 1735w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 15Z (left) accumulated precipitation forecast and 18Z (right) through to 5 am on August 20th.<\/figcaption><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\">Analysis<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The upper-level water vapor satellite image at 4 am this morning is below. Three Tropical Upper Tropospheric Trough (TUTT) lows are visible.&nbsp;One&nbsp;TUTT low&nbsp;is moving west from the Baja Peninsula into the Pacific Ocean, another&nbsp;is moving west from northeast Mexico west of Brownsville, and&nbsp;a third&nbsp;remains stationary in central Florida. The polar low is well off the west coast behind&nbsp;the associated jet stream. These two features have not moved much over the last 24 hours, hence the term quasi-stationary.&nbsp;<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"589\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-093402-1024x589.png\" alt=\"\" class=\"wp-image-4759\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-093402-1024x589.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-093402-300x173.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-093402-768x442.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-093402.png 1117w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">GOES-19 upper-level water vapor image August 20th at 4 am, College of DuPage.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">The&nbsp;visible satellite image from&nbsp;9:30 am&nbsp;shows the remnant circulation&nbsp;of the MCS that was in Phoenix last night winding&nbsp;down as it approaches the Colorado River, near Yuma.&nbsp;The circulation without the storms is a Mesoscale Convective Vortex (MCV), and it can steer storms that develop around its edge.&nbsp;Subsidence is typically present in its wake.&nbsp;&nbsp;<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"680\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-162-1024x680.png\" alt=\"\" class=\"wp-image-4761\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-162-1024x680.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-162-300x199.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-162-768x510.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-162.png 1222w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">GOES-19 visible satellite imagery from August 20th at 9:30 am, College of DuPage.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Surface dewpoints have changed little since yesterday, as Gulf Surge moisture remains in place; perhaps a slight increase in far southeast Arizona.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"567\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-094603-1024x567.png\" alt=\"\" class=\"wp-image-4762\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-094603-1024x567.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-094603-300x166.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-094603-768x425.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-094603.png 1445w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Surface weather station observations for Arizona and New Mexico at 7:00 am, <a href=\"https:\/\/www.weather.gov\/wrh\/hazards?&amp;zoom=8&amp;scroll_zoom=false&amp;center=32.656025851099066,-110.76888628244107&amp;boundaries=false,true,false,false,false,false,false,false,false,false,false&amp;tab=observation&amp;hazard=true&amp;hazard_type=all&amp;hazard_opacity=80&amp;obs=true&amp;obs_type=weather&amp;elements=temp,wind,gust&amp;temp_filter=-80,130&amp;gust_filter=0,150&amp;rh_filter=0,100&amp;elev_filter=-300,14000&amp;precip_filter=0.01,30&amp;obs_popup=false&amp;obs_density=60&amp;obs_provider=ALL\">NWS<\/a><\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">The HRRR-UA WRF 12Z initialization (left) and observed (right) sounding for Phoenix at 5 am are shown below. Both soundings are classic onion-shaped, showing cooling at 800 mb below from last night&#8217;s MCS.&nbsp;The observed sounding has nearly twice the Convective Inhibition (CIN) as the forecast&nbsp;initialization.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"578\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-094853-1024x578.png\" alt=\"\" class=\"wp-image-4765\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-094853-1024x578.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-094853-300x169.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-094853-768x434.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-094853.png 1411w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z (left) initialization and observed sounding (right) at Phoenix for 5 am this morning.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">At 250mb, the monsoon high is over west-central Arizona, with the two TUTT lows further south and moving west. The TUTT&nbsp;off the Baja coast will&nbsp;move&nbsp;further west and get absorbed by the jet stream. The TUTT low west of Brownsville will move into central Mexico and change our&nbsp;flow to southeast&nbsp;by Saturday as the monsoon ridge moves&nbsp;to the Texas Panhandle.&nbsp;&nbsp;<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"850\" height=\"852\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095431.png\" alt=\"\" class=\"wp-image-4766\" style=\"aspect-ratio:0.9976444457814775;width:612px;height:auto\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095431.png 850w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095431-300x300.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095431-150x150.png 150w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095431-768x770.png 768w\" sizes=\"auto, (max-width: 850px) 100vw, 850px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">At 500mb, the monsoon ridge stretches across northern Arizona with a deep fetch of easterly flow with three waves moving west underneath the ridge.&nbsp;<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"850\" height=\"851\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095712.png\" alt=\"\" class=\"wp-image-4767\" style=\"aspect-ratio:0.9988307290303978;width:618px;height:auto\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095712.png 850w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095712-300x300.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095712-150x150.png 150w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095712-768x769.png 768w\" sizes=\"auto, (max-width: 850px) 100vw, 850px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">At 700mb, the monsoon high has three&nbsp;centers partially created by the action of the troughs moving westward&nbsp;underneath the ridges. The one extending south into Mexico from Deming may enhance storms&nbsp;in far southeast Arizona this afternoon.&nbsp;<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"860\" height=\"861\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095904.png\" alt=\"\" class=\"wp-image-4768\" style=\"aspect-ratio:0.9988307290303978;width:635px;height:auto\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095904.png 860w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095904-300x300.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095904-150x150.png 150w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-095904-768x769.png 768w\" sizes=\"auto, (max-width: 860px) 100vw, 860px\" \/><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\">Today<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The&nbsp;forecast sounding for Flagstaff at 1 pm&nbsp;(left) and&nbsp;Springerville&nbsp;at 3:30 pm&nbsp;(right)&nbsp;both show&nbsp;an atmosphere that is favorable for thunderstorm&nbsp;development as they were not affected by last night&#8217;s MCS.&nbsp;The&nbsp;Phoenix, and Tucson, sounding show the onion shape that indicates&nbsp;the CAPE will not be able to overcome the CIN.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"573\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-101512-1024x573.png\" alt=\"\" class=\"wp-image-4769\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-101512-1024x573.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-101512-300x168.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-101512-768x430.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/Screenshot-2026-08-20-101512.png 1409w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z forecast soundings for Flagstaff at 1 pm (left) and Springerville at 3:30 pm (right).<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Today,&nbsp;the majority&nbsp;of thunderstorms form from the Mogollon Rim into northern Arizona and New Mexico on the Colorado Plateau.<\/p>\n\n\n\n<figure class=\"wp-block-video aligncenter\"><video height=\"568\" style=\"aspect-ratio: 1732 \/ 568;\" width=\"1732\" autoplay controls loop muted src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/20260820-1720-21.9221453.mp4\" playsinline><\/video><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z simulated radar reflectivity (left) and 10-meter wind speed (right) from 2 pm to 3 am.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Storms will be isolated in the mountains in southeast Arizona, including Tucson, but as can be seen by the 24-hour total rainfall (left) not&nbsp;much rain falls with these storms. Some additional rainfall is expected Friday (right) from scattered thunderstorms.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"335\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-163-1024x335.png\" alt=\"\" class=\"wp-image-4772\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-163-1024x335.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-163-300x98.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-163-768x251.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-163-1536x503.png 1536w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-163.png 1733w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z 24-hour accumulated precipitation (left) and 48-hour accumulation (right).<\/figcaption><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\">Tomorrow<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Scattered showers and thunderstorms will develop in&nbsp;Arizona, but&nbsp;heavy&nbsp;rain or strong winds is not expected. The storms&nbsp;will mostly stay away from the Phoenix and Tucson&nbsp;valley.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"677\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-164-1024x677.png\" alt=\"\" class=\"wp-image-4773\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-164-1024x677.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-164-300x198.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-164-768x508.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-164.png 1142w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z simulated radar reflectivity tomorrow at 3:30 pm.<\/figcaption><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\">Outlook<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">On Saturday&nbsp;northern Arizona and New Mexico&nbsp;will not have storms, although the some will develop&nbsp;in western&nbsp;Pima County&nbsp;and&nbsp;north to Maricopa County and Phoenix.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"680\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-165-1024x680.png\" alt=\"\" class=\"wp-image-4774\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-165-1024x680.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-165-300x199.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-165-768x510.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-165.png 1133w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z simulated radar reflectivity Saturday at 5:30 pm.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Long-range global model forecasts&nbsp;have backed off to low grade monsoon&nbsp;levels for&nbsp;the&nbsp;weekend and most of next; note the QPF scale has changed to 0 to 0.25&#8243;, so even the outlier are below 0.25&#8243;.&nbsp;<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"816\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-166-1024x816.png\" alt=\"\" class=\"wp-image-4775\" style=\"aspect-ratio:1.2548862847750155;width:776px;height:auto\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-166-1024x816.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-166-300x239.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-166-768x612.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/08\/image-166.png 1081w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Global Ensemble Forecast System (GEFS) ensemble forecasts of 2-meter temperature (top) and 3-hour accumulated precipitation (bottom), NCAR.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Discussion written by Pat Holbrook and Patrick Bunn<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Summary Water vapor satellite imagery shows three Tropical Upper Tropospheric Troughs (TUTT); one moving off the Baja Peninsula, another west of Brownsville, and another in central Florida. The monsoon high is positioned over west-central Arizona, influencing the movement of these troughs and the overall flow pattern. A remnant mesoscale convective vortex (MCV) from last night&#8217;s &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":[8],"class_list":["post-4744","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-8"],"_links":{"self":[{"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=\/wp\/v2\/posts\/4744","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=4744"}],"version-history":[{"count":14,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=\/wp\/v2\/posts\/4744\/revisions"}],"predecessor-version":[{"id":4782,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=\/wp\/v2\/posts\/4744\/revisions\/4782"}],"wp:attachment":[{"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4744"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4744"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4744"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}