Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
466 FXUS65 KTWC 082043 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 143 PM MST Fri Aug 8 2025 .SYNOPSIS...The very hot temperatures of the past several days will be trending down today and through the weekend. A low grade monsoon pattern continues with chances of precipitation today mainly south to southwest of Tucson and in the White Mountains. Precipitation chances expand to much of the remainder of southeast Arizona this weekend. Above normal temperatures next week. && .KEY MESSAGES... Today: Hot temperatures continue across southeast Arizona. Extreme Heat Warning in effect through 8 PM this evening. Potential for record to near-record high temperatures exists for multiple locations this afternoon. Isolated to scattered thunderstorm activity expected this afternoon mainly south of Tucson and up in the White Mountains. Main threats of strong gusty winds, blowing dust issues, and lightning. Weekend: Temperatures will continue to trend down, but remain above normal through the weekend into the new week. Moderate HeatRisk for the region with pockets of Major HeatRisk on Saturday. More active weekend for isolated to scattered thunderstorms. Main threats will be strong gusty winds, lighting, and locally brief heavy rainfall. && .DISCUSSION...Visible satellite show a small cumulus field bubbling up around the Chiricahua Mountains and in Santa Cruz County. Precipitable water content in Tucson is sitting at 1.14 inches with the higher values off to the west. This just below normal amount of moisture in the atmosphere, but there is ample surface moisture and hot temperatures to help initiate thunderstorms. The current RAP analysis has DCAPE values of 1800 J/kg and higher with CIN values zero in Cochise County and slowly eroding out west. The cumulus field is validating that we have the instability building more south of Tucson and up towards the White Mountains. The latest HRRR model have convection initiating by 2 pm in Cochise to Santa Cruz. The International Border has the better ingredients for storms. With the high DCAPE values, there is a high chance for strong gusty winds. 12Z HREF gusts probability greater than 30 kts has over 70 percent within the Santa Cruz County with lower values elsewhere. Therefore, high confidence for gusty outflows for Southeast Arizona today with low probability for wetting rain. Storms will diminish around sunset with potential for isolated storms popping around the region in the late evening from outflow boundaries colliding. Tomorrow, chances for thunderstorms and rain showers will spread across the region. A trough to our north will be moving through the northern rockies region splitting our high pressure center into two. Locations will be east and west of us. This will bring a more active pattern as the longer range convecting allowing models has shown so far. We will have high CAPE values in the region which will be spreading later tonight. The combination of the moisture, hot temperatures, and instability will provide a suitable environment for thunderstorms. There is a signal for a wind threat tomorrow. The HREF has a 10 percent chance for gust greater than 50 kts in Cochise County. Plus, the calibrated SPC GEFS product has at least 15 percent of severe winds. Growing confidence for a more active and impactful monsoon day compared to the previous days. Looking ahead, chances for thunderstorms and rain showers will stick around each day. There will be day to day variability as the upper level pattern shifts the moisture around the region. Long range ensemble models have agreement of a better monsoon moisture for the second half for the new week. Pointing another active monsoon, and of course, better chances for rain. && .AVIATION...Valid through 10/00Z. Scattered to locally broken clouds at 9k-12k ft AGL with isolated to scattered thunderstorms mainly south of KTUS through 09/05Z. Gusty winds up to 45 kts possible near thunderstorms, especially near KOLS between 08/22Z and 09/01Z. Otherwise SFC winds light and terrain driven winds with some afternoon gustiness. Additional thunderstorms expected to develop Saturday after 09/20Z. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...After a very hot week, temperatures will continue to trend down through through the weekend. Temperatures will be several degrees above normal through next week. Near normal amount of monsoon moisture will move in starting today. This will bring isolated to scattered thunderstorms this afternoon, mainly south of Tucson and up towards the White Mountains. Thunderstorm coverage will expand tomorrow along with better wetting rain chances. Daily chances for thunderstorms and wetting rain showers will continue through the new week with daily variability on coverage and intensity of thunderstorms and rain showers. Min RHs will generally be around 14-22 percent in the lower elevations and 20-30 percent in the mountains. There will be breezes today for portions of the Gila River and central Pima County. These breezes will last through most of tonight, especially on the lee side of terrain features. Otherwise, winds will generally be less than 15 mph with typical afternoon gusts up to 20 mph into the new week. && .TWC WATCHES/WARNINGS/ADVISORIES... Extreme Heat Warning until 8 PM MST this evening for AZZ501>509- 515. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson