Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
890 FXUS65 KTWC 302033 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 133 PM MST Wed Jul 30 2025 .SYNOPSIS... Thunderstorm chances continue through the work week, with highest chances east and south of Tucson. Chances begin to decrease Friday as dry air pushes in through the weekend. Extreme heat is expected Friday through the weekend. && .KEY MESSAGES... -Thunderstorm chances continue through the work week. Chances begin to decrease Friday as dry air pushes in through the weekend. -Isolated heavy rain, strong wind gust, and blowing dust threats possible with thunderstorms today and Thursday. -Extreme heat is expected Friday through the weekend. Temperatures remain warmer than normal through next week. && .DISCUSSION... The overall weather pattern over the Southwest US is dominated by an expansive upper level high centered over Texas, but stretching westward toward the eastern Pacific. Water vapor satellite imagery is picking up on an axis of midlevel moisture associated with vorticity stretching from the Gulf of California northeastward through central New Mexico. As of this writing, thunderstorms are forming along this axis, and in particular along the White and Chiricahua Mountains and portions of Graham, Greenlee and Cochise Counties. Today is looking to play out like a typical monsoon day, with thunderstorms initially forming over mountains, and becoming chaotic in nature due to outflow boundary collisions. Storms will generally have a slow NE to SW motion today. Some of these storms may impact Tucson or areas slightly west getting toward the late afternoon and evening hours. Isolated heavy rain, and strong wind gusts potentially producing blowing dust will be the main weather threats today. Subtle changes in the overall pattern Thursday as the center of the upper ridge drifts westward. This will have the effect of potentially increasing coverage of thunderstorms during the day, with most of the forecast area having a chance of storm activity. Storm motion looks to be even lower than today, which may tilt the risk scale slightly more toward rain threats, though wind-related hazards will persist. The potential for thunderstorms begins to drop off on Friday as the upper level ridge moves over southern Arizona, increasing subsidence over the region. We are still carrying 20-50% chances of thunderstorms across the forecast area Friday, with those odds diminishing further through the weekend. Heat replaces storm activity as the primary weather risk Friday through Sunday as heights and thicknesses increase. Saturday currently looks to be the hottest day of this stretch, with the National Blend of Models highlighting a 20-50% chance of temperatures exceeding 110 degrees, depending on location. With the heightened HeatRisk, we have issued an Extreme Heat Warning across much of the lower elevations for the Friday to Sunday timeframe. The upper ridge drifts slightly eastward again for next week, which should allow for some moisture to return to the region. There is a high degree of uncertainty in the details this far out though...if moisture is limited, extreme heat may end up persisting. The Climate Prediction Center continues to highlight odds favoring warmer and drier than normal continuing in the 6-10 and 7-14 day periods. && .AVIATION...Valid through 01/00Z. Isolated to scattered thunderstorms possible through 31/07Z, with cloud bases generally 9k-13k and greater coverage likely near and east of KSAD-KOLS. Gusty erratic winds possible with any thunderstorms. Otherwise winds mainly under 12 kts, with occasional afternoon gusts to 20 kts. Scattered thunderstorms possible again after 31/20Z. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER... Minimum relative humidities mainly above 25 percent east of Tucson-Nogales, and 10-20 percent to the west. Winds mainly light and under 12 mph, with occasional afternoon gusts. Thunderstorm chances continue through Thursday, then a drying trend is expected through this weekend. Forecast high temperatures remain above normal through the weekend. && .TWC WATCHES/WARNINGS/ADVISORIES... Extreme Heat Warning from 10 AM Friday to 8 PM MST Sunday for AZZ501>507-509-515. && $$ Public...Dang Aviation...Dang Fire Weather....Dang Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson