{"id":5277,"date":"2026-09-15T18:12:43","date_gmt":"2026-09-15T18:12:43","guid":{"rendered":"https:\/\/discussions.weather.arizona.edu\/?p=5277"},"modified":"2026-09-15T18:13:25","modified_gmt":"2026-09-15T18:13:25","slug":"september-15th-2026-more-thunderstorms-are-forecast-for-this-afternoon-and-evening-and-am-pm-thursday-morning-afternoon-some-with-heavy-rain-strong-winds-and-hail-monsoon-moisture-will-be-cut-of","status":"publish","type":"post","link":"https:\/\/discussions.weather.arizona.edu\/?p=5277","title":{"rendered":"September 15th, 2026: More thunderstorms are forecast for this afternoon and evening and am\/pm Thursday morning\/afternoon, some with heavy rain, strong winds, and hail. Monsoon moisture will be cut off by the polar jet stream by Friday"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">Summary<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Tropical Storm Norbert is weakening as it moves west, and the Pacific basin is generally calm. Moisture from the tropical Pacific continues to flow up the Gulf of California and across Arizona, contributing to scattered thunderstorms, especially in southern and central Arizona. The monsoon flow has shifted slightly east, and surface conditions remain favorable for storms with high dewpoints across southern Arizona. <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Forecasts show thunderstorms moving from Tucson in the late afternoon to Phoenix by late evening, with additional storms expected tomorrow from the morning and again in the afternoon, particularly along a similar northward track. Significant rainfall is forecast for central Arizona through Wednesday, but by Thursday and Friday, most storm activity will shift into New Mexico. Monsoon moisture is expected to be cut off in Arizona by Friday, likely marking the end of this active late-season period.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Yesterday&#8217;s Weather<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">What a day for thunderstorms in Arizona! The infrared satellite animation below shows the progression of the thunderstorm cluster from Los Mochis, Sinaloa, MX on Sunday into southeast Arizona near the\u00a0international border by 4:00 pm Monday. \u00a0<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The storm cluster moved at about 40 mph.\u00a0Because large-scale winds were less than 20 mph along the Gulf of California, the movement was driven by propagation along an outflow boundary produced by the storm cluster. The gust front moved north, staying west of the Sierra Madre Occidental. Several stations in Sonora reported wind gusts near 40 mph as the storms passed. When the storms reached maximum development, upper-level divergence in northwest Mexico aided the thunderstorms. The outflow boundary moved into Phoenix by 9:00 pm, initiating thunderstorms there too.\u00a0<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This has happened in previous years with a cluster of storms moving northward as this one did. In some years, the storms explode in Arizona like we saw yesterday; in other years, they weaken if they move into an unfavorable environment.<\/p>\n\n\n\n<figure class=\"wp-block-video aligncenter\"><video height=\"776\" style=\"aspect-ratio: 844 \/ 776;\" width=\"844\" autoplay controls loop muted src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/20260915-1635-18.7321870.mp4\" playsinline><\/video><figcaption class=\"wp-element-caption\">GOES-19 infrared satellite imagery from September 13th at noon through September 4th at 8:50 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. The forecast gets the precipitation pattern correct, but underestimates the total precipitation amount.<\/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-65-1024x336.png\" alt=\"\" class=\"wp-image-5281\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-65-1024x336.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-65-300x98.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-65-768x252.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-65-1536x503.png 1536w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-65.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 September 14th.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Precipitation totals from the Pima County Flood Control District Alert gauges show that heavy rain fell across eastern Pima County. At least 3 swift water rescues occurred in Tucson yesterday. Though the airport didn\u2019t get more than a trace amount, over\u00a01\u201d\u00a0fell on parts of the\u00a0east side, 0.5-0.75\u201d from downtown up the Santa Cruz River, and over 2\u201d at locations on the west side. <\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"895\" height=\"795\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-66.png\" alt=\"\" class=\"wp-image-5282\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-66.png 895w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-66-300x266.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-66-768x682.png 768w\" sizes=\"auto, (max-width: 895px) 100vw, 895px\" \/><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\">In Maricopa County, storms mainly stayed east of I-10, developing along the outflow boundary.\u00a0Totals above 0.5 are in yellow, and the maximum was 1.1&#8243; northwest of Apache Junction. <\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"960\" height=\"687\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-67.png\" alt=\"\" class=\"wp-image-5283\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-67.png 960w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-67-300x215.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-67-768x550.png 768w\" sizes=\"auto, (max-width: 960px) 100vw, 960px\" \/><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<h2 class=\"wp-block-heading\">Analysis<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Tropical Storm Norbert is slowly dissipating as it moves west; the tropical Pacific Ocean is rather quiet right now.\u00a0<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"616\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-68-1024x616.png\" alt=\"\" class=\"wp-image-5285\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-68-1024x616.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-68-300x181.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-68-768x462.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-68.png 1032w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><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\">Moisture continues to flow from the tropical Pacific up the Gulf of California, then turns northwest across Arizona and continues to the Great Lakes (green arrow).\u00a0The Tropical Upper Tropospheric Trough (TUTT), with several low-pressure centers along it, extends from the eastern Pacific Ocean to the central Gulf of Mexico, then into the Caribbean Sea and eastward into the tropical Atlantic Ocean (red dashed). The polar low and jet in the Pacific Northwest are moving southeast (blue \u201cL\u201d and arrow). Another cluster of storms is near Los Mochis again this morning, moving northwest up the Gulf of California, but moving more slowly than yesterday\u2019s cluster.\u00a0<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"550\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-100433-1024x550.png\" alt=\"\" class=\"wp-image-5287\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-100433-1024x550.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-100433-300x161.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-100433-768x413.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-100433.png 1172w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">GOES-19 upper-level water vapor image, September 15th at 8 am, College of DuPage.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Visible satellite imagery overlaid with mosaic radar from 7:30 am this morning\u00a0shows only a few showers across northern Arizona and eastern Arizona into\u00a0New Mexico. The monsoon flow has shifted slightly east.\u00a0<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"673\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-100805-1024x673.png\" alt=\"\" class=\"wp-image-5289\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-100805-1024x673.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-100805-300x197.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-100805-768x505.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-100805.png 1232w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">GOES-19 visible satellite imagery from September 15th at 7:30 am, College of DuPage.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Surface moisture is in place for thunderstorms today, with above 60\u00b0F 2-meter\u00a0dewpoint temperatures across the southern half of Arizona. \u00a0\u00a0<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"556\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-101831-1024x556.png\" alt=\"\" class=\"wp-image-5290\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-101831-1024x556.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-101831-300x163.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-101831-768x417.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-101831.png 1467w\" 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 below. The forecast initialization sounding and the observed sounding are amazingly similar.\u00a0<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"575\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-102133-1024x575.png\" alt=\"\" class=\"wp-image-5291\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-102133-1024x575.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-102133-300x168.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-102133-768x431.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-102133.png 1411w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z (left) initialization and observed sounding (right) for Phoenix at 5 am this morning.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">At 250mb, the polar jet is from central California into southern Wyoming. The high-pressure center is over southeast New Mexico, with monsoon flow from Baja California to Colorado.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"847\" height=\"852\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-102635.png\" alt=\"\" class=\"wp-image-5293\" style=\"aspect-ratio:0.9941220465223253;width:582px;height:auto\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-102635.png 847w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-102635-298x300.png 298w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-102635-150x150.png 150w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-102635-768x773.png 768w\" sizes=\"auto, (max-width: 847px) 100vw, 847px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">At 500mb, the polar jet is in a similar location as yesterday, flowing from California to Nebraska, while the monsoon ridge is in Alabama, with the ridge axis extending west to northern Mexico.\u00a0<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"847\" height=\"851\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-103646.png\" alt=\"\" class=\"wp-image-5294\" style=\"aspect-ratio:0.9952999627555135;width:596px;height:auto\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-103646.png 847w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-103646-300x300.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-103646-150x150.png 150w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-103646-768x772.png 768w\" sizes=\"auto, (max-width: 847px) 100vw, 847px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Two moisture flows are entering the AZ\/NM region at 700mb. The flow up the Gulf of California is due to the polar low\/jet stream to the north. The flow out of northern Mexico into southeast Arizona is due to flow around the monsoon high near Big Bend, TX.\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=\"857\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-104006.png\" alt=\"\" class=\"wp-image-5295\" style=\"aspect-ratio:0.994161255900651;width:606px;height:auto\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-104006.png 852w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-104006-298x300.png 298w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-104006-150x150.png 150w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-104006-768x773.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\">The 12Z HRRR-UA WRF forecast sounding for Phoenix at 10:30 pm (left) shows an atmosphere with plenty of Convective Available Potential Energy (CAPE) for storms but needing a little push from outflow to overcome the Convective Inhibition (CIN). At 6:00 pm in Tucson (right), the CIN is lower and should be overcome by nearby thunderstorm outflows. The outflow from these storms will move northwest into Phoenix.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"572\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-104507-1024x572.png\" alt=\"\" class=\"wp-image-5296\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-104507-1024x572.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-104507-300x168.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-104507-768x429.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/Screenshot-2026-09-15-104507.png 1419w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z forecast soundings for Phoenix at 10:30 pm (left) and Tucson at 6 pm (right).<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">The forecast radar reflectivity shows the thunderstorms that move from Tucson at around 6 pm to Phoenix about midnight along and east I-10.\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\/20260915-1748-17.5206572.mp4\" playsinline><\/video><figcaption class=\"wp-element-caption\">HRRR-UA WRF simulated radar reflectivity 12Z forecast from 3 pm to 6:30 am tomorrow.<\/figcaption><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Tomorrow<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A cluster of storms in the Gulf of California will move northward along a similar track to Monday\u2019s activity, but moving more slowly. The cluster is just south of the border by 5 am and reaches Phoenix around 10 am. By afternoon, additional storms form in southerly flow in the Grand Canyon, Flagstaff, and central Arizona to the International Border in New Mexico. <\/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\/20260915-1751-21.4209707.mp4\" playsinline><\/video><figcaption class=\"wp-element-caption\">HRRR-UA WRF simulated radar reflectivity 12Z forecast from 4 am tomorrow to 5 pm.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">The total precipitation through 24 (left) and 48 hours (right) is shown below. The position of the heaviest rain band on Wednesday will be dependent on the position of the short-wave trough associated with the polar jet to the north. \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-71-1024x334.png\" alt=\"\" class=\"wp-image-5300\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-71-1024x334.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-71-300x98.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-71-768x251.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-71-1536x502.png 1536w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-71.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\">Wednesday should be the last day of significant precipitation in Arizona, as most storms will move into New Mexico Thursday evening and Friday.\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-72-1024x334.png\" alt=\"\" class=\"wp-image-5301\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-72-1024x334.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-72-300x98.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-72-768x251.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-72-1536x501.png 1536w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-72.png 1737w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">HRRR-UA WRF 12Z simulated radar reflectivity for Wednesday at 7 pm (left) and Thursday at 7 pm (right).<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Monsoon moisture is cut off in Arizona by Friday, and this will be the end of this late-season active period. The hurricane center outlook is quiet, so unless something changes for the last week of September, this could be the end of the monsoon season.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"797\" src=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-73-1024x797.png\" alt=\"\" class=\"wp-image-5302\" srcset=\"https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-73-1024x797.png 1024w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-73-300x233.png 300w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-73-768x597.png 768w, https:\/\/discussions.weather.arizona.edu\/wp-content\/uploads\/2026\/09\/image-73.png 1112w\" 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 Tropical Storm Norbert is weakening as it moves west, and the Pacific basin is generally calm. Moisture from the tropical Pacific continues to flow up the Gulf of California and across Arizona, contributing to scattered thunderstorms, especially in southern and central Arizona. The monsoon flow has shifted slightly east, and surface conditions remain favorable &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-5277","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\/5277","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=5277"}],"version-history":[{"count":7,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=\/wp\/v2\/posts\/5277\/revisions"}],"predecessor-version":[{"id":5305,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=\/wp\/v2\/posts\/5277\/revisions\/5305"}],"wp:attachment":[{"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5277"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5277"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/discussions.weather.arizona.edu\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5277"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}