Forecast Discussion
149 FXUS65 KTWC 111030 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 330 AM MST Fri Sep 11 2026 .SYNOPSIS...A more active day is forecast across southeast Arizona today with isolated to scattered showers and thunderstorms. Main threat from storms today will be heavy rain and localized flash flooding, especially across Santa Cruz county and southwest Cochise county. A more typical isolated to scattered coverage of storms is forecast this weekend into next week. Daily high temperatures will fluctuate between near normal and a few degrees below normal. && .DISCUSSION...Broad high pressure over the desert southwest with mid-level flow turning to the southeast this afternoon and to the south tonight as the upper high moves into SW NM. Higher up around 300-200 mb, the flow will be westerly that becomes divergent along the Intl border this afternoon and evening. PWATs range from 1.25" near AZ/NM border to 1.70" across western Pima county. SE AZ will see much more thunderstorm activity today versus yesterday with the most recent runs from the HRRR, RRFS and HREF all highlighting SW Cochise county and most of Santa Cruz county as the area for concern today from scattered to numerous thunderstorms. The main threat in this area will be very heavy rain with some of the strongest cores producing rainfall rates of 1"-2.5"/hr. HREF has this area painted with 10+% chance for 3-hour rainfall totals exceeding 3+". WPCs ERO has this area under slight risk, at least 15% chance, for excessive rain leading to flash flooding. Also, parts of eastern Santa Cruz county and SW Cochise county has seen heavy rain over the past 72 hours, so the soils are wet, and the San Pedro has had some increased flow several days ago. With that said I contemplated hoisting a small flash flood watch area between I-19 in Santa Cruz county east to Sierra Vista area. Will let day shift look at new model data in case one needs to be issued. Saturday: Might be a down day depending how today evolves. Sunday through Thursday: Southerly flow aloft will keep slightly above normal moisture across the area for mid-September resulting in a chance of showers and thunderstorms with day-to- day variability in areal coverage of storms, mainly across the eastern half of the forecast area. High temperatures through Monday will be at or slightly above normal then be at or slightly below normal Tuesday through Thursday. && .AVIATION...Valid thru 12/12Z. Sct debris clouds mostly above 10k ft AGL thru 11/16z. Aft 11/19z SCT-BKN 7k-10k ft AGL with layers abv. ISOLD to SCT SHRA/TSRA mainly S and E of KTUS. Isold VSBY 1-3 miles nr TS. Lclzd TS outflow winds of 30-40 kts. Otrw, SFC winds terrain driven less than 10 kts until 11/18z and then again aft 12/04z. At other times, WLY/NWLY 6-10 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Scattered showers and thunderstorms today. A more typical isolated to scattered coverage of storms is forecast this weekend into next week. High temperatures will will fluctuate between near normal and a few degrees below normal. Min RH values mainly 20 to 45 percent in the valleys and 35 to 65 percent in the mountains over the next week. RH recoveries will continue to be excellent overnight. Winds will generally remain less than 15 mph and terrain driven. Gusty and erratic winds will accompany thunderstorms. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook, X, YouTube, and at weather.gov/Tucson
NWS OUN Office Area Forecast Discussion