Forecast Discussion
406 FXUS65 KTWC 210843 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 143 AM MST Thu May 21 2026 .SYNOPSIS...Dry and warm conditions for the remainder of the week with the exception of today`s afternoon breezes. Another weather system will be moving into the region by the late weekend, bringing slight chances for rain showers and thunderstorms especially on Monday. && .DISCUSSION... The upper air pattern has a general troughiness pattern over the western United States. There is a low pressure circulation pulling away from the tip of the trough axis over southern California. This low will track to the southeast, below Arizona, starting later today and into the weekend. As it does that, areas along the International Border and in Cochise County will experience southwesterly breezes with gusts up up 25 mph. Friday and into Sunday...Southeast Arizona will generally be in a benign pattern as the low passes to the south of the state. It will bring mid-to-upper level moisture into the region, leading to less than 5-10% chances for rain showers in the afternoons, but generally it will be a few cloud build ups and possibly virga over the higher terrain. Temperatures will rise 1-2 degrees each day and staying near normal for this time of year. Monday and into the new week...Another low pressure center will move into the region, bringing better moisture. PWATs will be between 0.6 to 0.7 inches by Monday. Thus, chances for rain showers and thunderstorms be increasing late Sunday to early Monday. Monday afternoon has the better chances for thunderstorm and rain shower development due to higher instability from the surface heating and some upper air dynamics with the low. Right now, chances for development are still around 15-30% with the higher terrain having the better chances. Winds will also start to pick up as the low moves over Arizona on Monday and into Tuesday. Ensemble models are trending towards a continuation of breezes through the new week due to a trough from the northwest plunging into the Great Basin, and gobbling up the low pressure center. && .AVIATION...valid through 22/12Z. SCT-BKN clouds AOA 20K feet AGL east of KTUS with SKC to the west this early morning becoming generally SKC wide by 21/15Z with the occasional passing high cirrus. SFC winds SELY/SLY less than 10 kts this morning and again after 22/03Z. By 21/18Z, SWLY/WLY at 10-15 kts with gusts up to 20-25 kts this afternoon. the strongest of winds will be between KALK to KDUG. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER... Dry conditions will continue through the remainder of the work week before mid-level moisture moves into the region by the weekend. Winds will generally be less than 15 mph through Sunday with the exception for Cochise county today with winds around 15 mph with strong gusts. Min relative humidities will be sitting in the teens to the mid-20s. Mid to upper level moisture will approach as early as this weekend south and east of Tucson. Enough moisture to produce daily afternoon cloud build ups starting as early on Friday. More impactful moisture will likely move in on Monday as another weather system moves through. There is a 10 to 30 percent chance of showers and thunderstorms Monday mainly from Tucson eastward, with lingering non-zero precipitation chances mainly in the White Mountains on Tuesday. Breezes will tick up Monday and Tuesday to around 15 mph and lasting through the most of the new week. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Visit us on Facebook, X, YouTube, and at weather.gov/Tucson
NWS TWC Office Area Forecast Discussion