Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
227 FXUS65 KTWC 122042 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 142 PM MST Wed Nov 12 2025 .SYNOPSIS... High temperatures will remain 5 to 10 degrees above normal through Friday. A low pressure system is then expected to impact the region this weekend, bringing chances for rain and high elevation mountain snow, much cooler temperatures, and breezy conditions. Unsettled conditions are expected to continue early next week along with below normal temperatures. && .DISCUSSION... As a trough in the eastern Pacific continues to slowly push southward, upper-level moisture is beginning to be pushed into the southwest US bringing high level clouds to our area. While the trough slowly approaches over the next few days, weak ridging will be the main upper-level pattern keeping temperatures at the surface 5 to 10 degrees above normal. Mentioned in the previous discussion, the aforementioned trough, likely becoming a closed low off the California coast by Friday, poses a hefty forecast challenge. Model runs continue to slow the evolution of the trough and subsequent cut off low and the associated impacts to the southwest US. The timing for precipitation in this forecast package begins Saturday morning for areas in far western Pima County and central Arizona pushing into the Tucson area Saturday evening. 12Z deterministic models, however, suggest that the precipitation will not arrive in western Pima county until Saturday evening/ Sunday morning. In addition to the uncertainty with the timing of precipitation, there is varying possibilities for the depth of the trough and corresponding cold air that would be introduced to the area. The biggest impact this has is on the chance and amount of precipitation and high elevation snow. As of now, snow level is forecast to get down to 8,500 ft in the White Mountains with around 1 to 2 inches of snow Saturday through Sunday night. Overall the message remains that there will likely be some sort of cool-down with chances for precipitation by this weekend...but there remain details to be worked out before then. Next week looks favorable for mean troughing to continue across the region with CPC outlooks leaning wetter and cooler. && .AVIATION...Valid through 14/00Z. FEW to SCT high clouds AOA 25k ft AGL will continue through 13/09Z becoming SCT to BKN AOA 25k ft AGL persisting through the forecast period. SFC winds will from the northwest generally less than 12 kts shifting to the southeast aft 13/04Z. SFC winds becoming northwesterly again aft 13/22Z through the forecast period. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER... Light terrain driven winds mainly under 12 mph through Wednesday with minimum relative humidities of 12 to 22 percent. A low pressure system will likely cross the region by this weekend, though recent trends have shown a delay in its arrival. Current forecast keeps Friday warmer and drier than previously advertised with cooler and wetter conditions arriving Saturday, though may be delayed until Sunday if the system continues to slow. Winds will likely increase and turn southwest with the arrival of the low. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Malarkey Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson