{"id":5306,"date":"2026-09-16T17:22:18","date_gmt":"2026-09-16T17:22:18","guid":{"rendered":"https:\/\/discussions.weather.arizona.edu\/?p=5306"},"modified":"2026-09-16T17:27:39","modified_gmt":"2026-09-16T17:27:39","slug":"september-16th-2026-thunderstorms-forecast-to-produce-heavy-rain-across-arizona-today-into-the-evening-moisture-is-pushed-east-into-new-mexico-by-thursday-morning","status":"publish","type":"post","link":"https:\/\/discussions.weather.arizona.edu\/?p=5306","title":{"rendered":"September 16th, 2026: Thunderstorms forecast to produce heavy rain across\u00a0Arizona\u00a0today into the evening.\u00a0Moisture is pushed east into New Mexico\u00a0by Thursday morning"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">Summary<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A tropical system in the Gulf of California is bringing significant moisture north into Arizona. The interaction between the polar low along the California coast and monsoon high pressure is driving moisture north into Arizona, resulting in widespread thunderstorms and heavy rainfall across central and southern Arizona. Forecasts indicate storms building through the day, with the heavy precipitation expected in Phoenix and Tucson areas. Most of the rainfall will occur today before moving east into New Mexico by Thursday, after which a dry period is expected for much of Arizona. Rainfall amounts may vary, but we should prepare for potentially heavy downpours and continue to monitor the situation for updates.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Yesterday&#8217;s Weather<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Monday&#8217;s activity drained much of the atmosphere&#8217;s energy, and yesterday&#8217;s storms in the Southwest remained along the edge of the previous day&#8217;s storms. Arizona saw scattered thunderstorms in central and western Maricopa County, the northeast part of the state, and over western New Mexico. Additional isolated thunderstorms were over the rest of New Mexico. Storms that were forecast to form along the Catalina Mountains turned out to be a stray cell that dropped 0.04 inches at one location.<\/p>\n\n\n\n<figure class=\"wp-block-video aligncenter\"><video height=\"806\" style=\"aspect-ratio: 1252 \/ 806;\" width=\"1252\" autoplay controls loop muted src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/20260916-1545-57.1822424.mp4\" playsinline><\/video><figcaption class=\"wp-element-caption\">GOES-19 visible satellite imagery overlaid with mosaic radar and GLM lightning from September 15th from 4 pm to 8 am, College of DuPage.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">To the south, a low-pressure system has been moving northward up the Gulf of California for the last two days. It has a low-level circulation and could be a tropical depression, but the National Hurricane Center (NHC) has largely ignored it, possibly because it doesn\u2019t have hurricane potential. Given its present track, the system should be a focal point for thunderstorms in Arizona today and tonight. Both the\u00a000Z GFS-UA WRF and HRRR-UA WRF forecasts for today correctly placed this system, though it doesn&#8217;t look as strong as it does on satellite.\u00a0<\/p>\n\n\n\n<figure class=\"wp-block-video aligncenter\"><video height=\"820\" style=\"aspect-ratio: 962 \/ 820;\" width=\"962\" autoplay controls loop muted src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/20260916-1549-52.2245790.mp4\" playsinline><\/video><figcaption class=\"wp-element-caption\">GOES-19 visible satellite imagery from September 14th from 8 am to September 16th 8 am, College of DuPage.<\/figcaption><\/figure>\n\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.\u00a0Yesterday\u2019s forecast error from Tucson to Phoenix was due to cooling in the lower atmosphere from Monday&#8217;s storms.\u00a0Otherwise, the forecast&#8217;s\u00a0precipitation\u00a0coverage and intensity were\u00a0about right.\u00a0<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"336\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-74-1024x336.png\" alt=\"\" class=\"wp-image-5312\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-74-1024x336.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-74-300x98.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-74-768x252.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-74-1536x504.png 1536w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-74.png 1737w\" 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 September 15th.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Precipitation totals for Tuesday in central and western Maricopa County are below; mostly light, other than 0.7&#8243; near Gillespie.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"942\" height=\"787\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-75.png\" alt=\"\" class=\"wp-image-5314\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-75.png 942w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-75-300x251.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-75-768x642.png 768w\" sizes=\"auto, (max-width: 942px) 100vw, 942px\" \/><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\" data-type=\"link\" data-id=\"https:\/\/alert.fcd.maricopa.gov\/alert\/Google\/v3\/gmap.html\">Alert Map<\/a>.<\/figcaption><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\">Analysis<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The NHC outlook is a day late in identifying the tropical system in the Gulf of California, which has been there for a few days, and this storm will be affecting Arizona over the next two days.\u00a0<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1032\" height=\"622\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-76-edited.png\" alt=\"\" class=\"wp-image-5316\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-76-edited.png 1032w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-76-edited-300x181.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-76-edited-1024x617.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-76-edited-768x463.png 768w\" sizes=\"auto, (max-width: 1032px) 100vw, 1032px\" \/><figcaption class=\"wp-element-caption\">National Hurricane Center <a href=\"https:\/\/www.nhc.noaa.gov\/\">outlook<\/a> for the Pacific basin<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">The polar low and jet stream have dropped southward, with the center of the low now positioned along the northwest California coast. The interaction between the low and the monsoon moisture is pulling tropical systems and moisture from northwest Mexico north into Arizona.\u00a0<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"649\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-090644-1024x649.png\" alt=\"\" class=\"wp-image-5317\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-090644-1024x649.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-090644-300x190.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-090644-768x487.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-090644.png 1136w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">GOES-19 upper-level water vapor image, September 16th at 8 am, College of DuPage.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">The visible satellite picture\u00a0overlaid with radar and lightning data from\u00a08\u00a0am shows the center of the tropical system; it\u2019s moving north towards Nogales. Showers and thunderstorms are north of the center and bending south in a spiral-type band. Other thunderstorms are in\u00a0Graham\u00a0County, extending east into\u00a0New Mexico.\u00a0The forecast shows these storms building and moving towards the Phoenix area by late morning. These thunderstorms are associated with upper air divergence in the area. Other showers are scattered across Cochise and Santa Cruz counties.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"571\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-091345-1024x571.png\" alt=\"\" class=\"wp-image-5319\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-091345-1024x571.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-091345-300x167.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-091345-768x428.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-091345.png 1112w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">GOES-19 visible satellite imagery from September 16th at 8 am, College of DuPage.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Surface moisture shows little change, with 60\u00b0F dewpoint temperatures covering half of Arizona and New Mexico.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"551\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-091654-1024x551.png\" alt=\"\" class=\"wp-image-5320\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-091654-1024x551.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-091654-300x161.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-091654-768x413.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-091654.png 1472w\" 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 observed sounding from Phoenix is very tropical. Precipitable water is nearly 2 inches, and convective temperature is in the low 90s\u00a0(only\u00a04 degrees above the present temperature). The forecast initialization is similar to observations, though with a little less precipitable water. Still,\u00a0the forecast shows storm initiation before noon.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"579\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-092128-1024x579.png\" alt=\"\" class=\"wp-image-5322\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-092128-1024x579.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-092128-300x170.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-092128-768x434.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-092128.png 1401w\" 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 tropical system is marked over Sonora, but it has no significant depth, so it isn\u2019t visible in the flow at this level.\u00a0The monsoon high is over El Paso with a Tropical Upper Tropospheric Trough\u00a0(TUTT) low near San Antonio. The short-wave trough off the West Coast of the Baja\u00a0Peninsula will help develop storms in Arizona today.\u00a0<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"851\" height=\"850\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-092746.png\" alt=\"\" class=\"wp-image-5323\" style=\"aspect-ratio:1.0011720117682756;width:588px;height:auto\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-092746.png 851w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-092746-300x300.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-092746-150x150.png 150w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-092746-768x767.png 768w\" sizes=\"auto, (max-width: 851px) 100vw, 851px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">At 500mb, the ridge is over Oklahoma with a long fetch of monsoon moisture feeding into Arizona. The tropical system continues to move northward up the Gulf of California.<\/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=\"845\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093326.png\" alt=\"\" class=\"wp-image-5324\" style=\"aspect-ratio:1.0059077315649803;width:606px;height:auto\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093326.png 850w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093326-300x298.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093326-150x150.png 150w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093326-768x763.png 768w\" sizes=\"auto, (max-width: 850px) 100vw, 850px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">At 700mb, plenty of moisture is being pulled northward ahead of the polar low dropping down the west coast of California\u00a0and the tropical system in the Gulf of California. The dry air over California will move into Arizona tomorrow.\u00a0<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"852\" height=\"860\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093658.png\" alt=\"\" class=\"wp-image-5325\" style=\"aspect-ratio:0.9907023039118047;width:618px;height:auto\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093658.png 852w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093658-297x300.png 297w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093658-150x150.png 150w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093658-768x775.png 768w\" sizes=\"auto, (max-width: 852px) 100vw, 852px\" \/><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\">Today<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Both the Phoenix (left) and Tucson (right) forecast soundings show each location reaching its\u00a0convective temperature this morning, with\u00a0thunderstorms\u00a0developing\u00a0and moving northward.\u00a0With high precipitable water, the storms could produce heavy rain across central and southern Arizona.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"577\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093944-1024x577.png\" alt=\"\" class=\"wp-image-5326\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093944-1024x577.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093944-300x169.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093944-768x433.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-093944.png 1415w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z forecast soundings for Phoenix at 10 am (left) and Tucson at 12 pm (right).<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">The forecast radar reflectivity shows a cluster of thunderstorms moving through the Phoenix metro area by 12:30 pm and other storms developing along and north of the international border in Pima, Santa Cruz, and Cochise counties. By\u00a02:30 pm, the forecast\u00a0has the storms moving into the Tucson metro area and continuing north into Pinal, Maricopa, and Graham counties.\u00a0The storms will move as far west as the Arizona\/Colorado border by tonight.\u00a0<\/p>\n\n\n\n<figure class=\"wp-block-video aligncenter\"><video height=\"752\" style=\"aspect-ratio: 1134 \/ 752;\" width=\"1134\" autoplay controls loop muted src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/20260916-1645-08.3436908.mp4\" playsinline><\/video><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z simulated radar reflectivity forecast from 8 am to 6 am tomorrow.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">UA WRF ensemble mean accumulated precipitation for the event is about 0.8&#8243; in Phoenix, with individual members ranging from 0.4 to 1.3&#8243;. In Tucson, the ensemble mean is about 0.35&#8243; with a range of 0.15 to 1.3&#8243;. It&#8217;s best to say all these amounts will likely fall in the general area, but it&#8217;s hard to predict whether there will be a direct hit at these airport locations; we should prepare for the worst, but expect precipitation amounts closer to the mean. <\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"549\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-094700-1024x549.png\" alt=\"\" class=\"wp-image-5328\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-094700-1024x549.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-094700-300x161.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-094700-768x412.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-094700-1536x824.png 1536w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-16-094700.png 1797w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">UA WRF ensemble precipitation plots for Phoenix (top) and Tucson (bottom)<\/figcaption><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\">Tomorrow<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">By midnight, most of the precipitation and the center of the tropical system will move out of Arizona, except in Maricopa and Yavapai counties. This area of storms is a convergence band to the south of the tropical system. The exact position of this area of storms is hard to predict right now, as it depends on what happens today, but as these storms move out of Arizona on Thursday, dry air in California will push moisture east into New Mexico.\u00a0On Thursday afternoon, the thunderstorms will have moved into northern New Mexico and southeast Arizona.\u00a0<\/p>\n\n\n\n<figure class=\"wp-block-video aligncenter\"><video height=\"756\" style=\"aspect-ratio: 1136 \/ 756;\" width=\"1136\" autoplay controls loop muted src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/20260916-1704-50.0721250.mp4\" playsinline><\/video><figcaption class=\"wp-element-caption\">HRRR-UA WRF simulated radar reflectivity 12Z forecast from midnight to Thursday at 10:30 pm.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">The total accumulated precipitation through 24 (left) and 48 hours (right) is shown below.\u00a0\u00a0Arizona receives most of the precipitation today, while New Mexico gets the heavy rain over the next 48-hour\u00a0period.\u00a0<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"334\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-78-1024x334.png\" alt=\"\" class=\"wp-image-5333\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-78-1024x334.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-78-300x98.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-78-768x251.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-78-1536x502.png 1536w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-78.png 1736w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z total precipitation forecast 24-hour accumulation (left) and 48-hour (right).<\/figcaption><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\">Outlook<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">On Friday, the monsoon moisture axis has been pushed east into New Mexico, leaving all but far southeast Arizona free of precipitation.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"675\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-79-1024x675.png\" alt=\"\" class=\"wp-image-5335\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-79-1024x675.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-79-300x198.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-79-768x507.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-79.png 1137w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z simulated radar reflectivity for Friday at 6 pm.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">\u00a0A dry period will follow today&#8217;s storms. Long-range global ensemble forecasts indicate some storms in about a week, but the monsoon flow is mainly over far eastern Arizona and New Mexico, leaving Phoenix and Tucson dry; this is very uncertain this far out. \u00a0<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"798\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-81-1024x798.png\" alt=\"\" class=\"wp-image-5337\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-81-1024x798.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-81-300x234.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-81-768x598.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-81.png 1117w\" 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 A tropical system in the Gulf of California is bringing significant moisture north into Arizona. The interaction between the polar low along the California coast and monsoon high pressure is driving moisture north into Arizona, resulting in widespread thunderstorms and heavy rainfall across central and southern Arizona. Forecasts indicate storms building through the day, &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-5306","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\/5306","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=5306"}],"version-history":[{"count":17,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=\/wp\/v2\/posts\/5306\/revisions"}],"predecessor-version":[{"id":5346,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=\/wp\/v2\/posts\/5306\/revisions\/5346"}],"wp:attachment":[{"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5306"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5306"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5306"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}