Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
233 FXUS65 KTWC 212033 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 133 PM MST Thu Aug 21 2025 .SYNOPSIS...Daily chances for thunderstorms and rain showers for Southeast Arizona with day to day variability on coverage and intensity. Above normal temperatures through the weekend and then trending down to near normal by the start of the new week. An Extreme Heat Warning in effect today through Friday and a Blowing Dust Advisory is in effect today from 4 PM to 9 PM this evening. && .DISCUSSION...A field of cumulus clouds have developed across the region some beginning to tower. Due to the location of high pressure, storms and showers will initiate along the higher terrain and move west to southwest across the region. Cochise County will have drier air, leading to lower chances for rain showers and thunderstorms. The 12Z HREF shows there is a 10% chance for 50kt winds this afternoon and with the 18Z sounding launched at TUS showing 1200 J/kg DCAPE, the main concern with thunderstorms this afternoon is strong outflow winds and blowing dust. There is a Blowing Dust Advisory for the area between Tucson and Phoenix along I-10 from 4 PM to 9 PM this evening. Expect visibilities to drop between 1/4 to 1 mile in blowing dust. The Extreme Heat Warning is still in effect today through tomorrow evening for the lower elevations of most of southern Arizona. Remember to stay hydrated and spend time indoors with A/C. If you need to spend time outside, wear light weight, light colored clothing and take frequent breaks. Take time to learn the signs of heat exhaustion and heat stroke, keeping in mind that heat stroke is an emergency. The Four Corners high will continue to influence the region. The high now oval shaped, is bring northeasterly flow across Southeastern Arizona. Heat is still a concern through tomorrow as low elevations will be above 100 degrees to 110 degrees with little overnight reprieve. Those areas will experience Major HeatRisk to isolated areas of Extreme HeatRisk through Friday. We will be trending down slightly in temperatures this weekend but areas will be on the cusp on Major HeatRisk per climatology. Overnight temperatures will continue to be high with widespread Major HeatRisk overnight. By the weekend, dryer air will push more into the region, but there will be enough instability and moisture to give daily chances. Higher terrain will naturally be the better areas for those rain chances. The Four Corners High will transform itself to ridge through the Great Basin by the start of the new week. Plus, troughiness will develop near the Pacific coast. This will open up southeasterly to southerly flow of deep monsoon moisture back into the region. Ensemble models show our PAWTs shooting up to 1.4-1.6 inches at Tucson with higher values towards Yuma. This tongue of moisture will provide better chances and coverage for rain showers and thunderstorms. As of this forecast, Tuesday through Wednesday appear to be the wettest days in the forecast period. Increase moisture will lower our temperatures and leaning below normal through the new week. && .AVIATION...Valid through 23/00Z. FEW to SCT clouds AOA 7k to 10k ft AGL with across the region. By Isolated to scattered -SHRA/-TSRA forming along the higher terrain and moving westward from 21/22 through 22/06Z. Lingering -SHRA is possible through 22/10z. SFC winds will generally be easterly- southeasterly less than 12 kts through the forecast period. Expect gusty and erratic winds with any -TSRA. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect daily chances for rain showers and thunderstorms into the new week. Dryer air will be moving into the region to create day to day variability of intensity and coverage. Temperatures will be running above normal through the weekend with an Extreme Heat Warning in effect through Friday in the lower elevations. Winds will generally remain less than 15 mph with the afternoon gustiness into the new week. Min RHs will be 15-20 percent in the low elevations and 20-30 in the mountains through the weekend. Deep monsoon moisture will return early next week to provide higher wetting rain chances and coverage as well as better min RHs and below normal temperatures. && && .TWC WATCHES/WARNINGS/ADVISORIES... Extreme Heat Warning until 8 PM MST Friday for AZZ501>507-509. Blowing Dust Advisory from 4 PM this afternoon to 9 PM MST this evening for AZZ502-504>506. && $$ Malarkey/ Strongman Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson