Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
184 FXUS65 KTWC 220850 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 150 AM MST Sat Aug 22 2026 .SYNOPSIS...Isolated to scattered afternoon and early evening thunderstorms expected this weekend, with daily but gradually reduced chances through next week. Strong, gusty winds and locally heavy rainfall will be possible with any thunderstorm. High temperatures will remain above normal through the coming week. && .DISCUSSION...Mostly clear to partly cloudy skies currently across southeast Arizona as a strong mid/upper level high is currently centered over New Mexico. Latest GOES total precipitable water imagery shows PWAT values around 1 inch for locales east of Tucson, increasing to around 1.2 to 1.4 inches from Tucson westward and these values are pretty close to normal for this time of year. As east to southeast steering flow continues around the high pressure, there will be enough moisture in place today for isolated to scattered showers and thunderstorms this afternoon into the evening. With the drier air east of Tucson, coverage will be a bit more isolated out that way, with scattered storms from Tucson south and westward. Main concern today with the storms is for strong gusty winds due to inverted-v profiles. The HREF 40-km neighborhood probability indicates a 10 to 30 percent chance of 50-kt winds from Santa Cruz County extending westward into the T.O. Nation and western Pima County. Locally heavy rain with the stronger storms resulting in an isolated flash flood threat will be a secondary concern. The Extreme Heat Warning also remains in place today for much of the region with highs 5 to 8 degrees above normal. While the mid/upper level high will initially remain to our east through early next week and weaken slightly Sunday and Monday, allowing temperatures to `cool` a few degrees those two days, that won`t last long as the high will transition westward into Arizona by Wednesday and strengthen once again with temperatures warming back up as an extended period of well above normal temperatures returns through the rest of the week into next weekend. In terms of storm coverage beyond today, moisture will remain in place, especially from Tucson westward allowing for continued isolated to scattered shower and thunderstorm chances mainly during the afternoon and evening hours Sunday and Monday. Thereafter, while some moisture remains, as the high builds west and subsidence aloft increases, storm coverage should decrease with a lower grade pattern for much of the remainder of the week. && .AVIATION...Valid through 23/12Z. SCT clouds 9-13k ft AGL this morning. Expect scattered SHRA/TSRA to develop aft 22/21Z, mainly west of a KFHU-KSAD line, diminishing by 23/06Z. Gusts in excess of 40 kts are expected with the stronger storms. Otherwise surface winds light and terrain driven. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Isolated to scattered thunderstorms expected this weekend with daily but gradually reduced chances as next week progresses. Temperatures will remain above normal through the coming week. Minimum relative humidity values mainly 15-30 percent each day with light and terrain driven wind. && .TWC WATCHES/WARNINGS/ADVISORIES... Extreme Heat Warning until 8 PM MST this evening for AZZ501-502- 504>506-509. && $$ Visit us on Facebook, X, YouTube, and at weather.gov/Tucson