Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
104 FXUS65 KTWC 212015 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 115 PM MST Fri Nov 21 2025 .SYNOPSIS...An active pattern continues through this weekend as a second system is expected to arrive late today through Sunday. Chances for precipitation hold off for much of southeastern Arizona until Saturday afternoon and evening, though showers may begin to move into western Pima western to central portions of Arizona today. && .DISCUSSION...As the cut-off low sits off the southern coast of California, moisture is being pulled into southern Arizona visualized by the overcast skies. This cut-off low is currently bringing a decent amount of rain to far southwestern Arizona and southern California and will very slowly make its way eastward to our area. Precipitation chances start in western Pima county this afternoon but then backs off overnight as the low oscillates slightly to the west. Chances for precipitation tomorrow begin in far western Pima county starting in the early afternoon around 1100 to 1200 MST expanding eastward becoming scattered to widespread by 1500 to 1600 MST. Isolated embedded thunderstorms will also be possible Saturday afternoon. Initially the air mass will be relatively warm with high temperatures only a degree or two below normal. Snow levels will be at or just above mountain peaks through Saturday evening, then drop to 7500 feet Saturday night as cooler air moves in. Initially precip will be all rain, turning to snow above 7500 feet Saturday night. Most of the precipitation will fall Saturday afternoon into the evening with rain amounts between 0.1" to 0.5" in the valleys and snow 1" to 2" on Mount Lemmon and 4" to 6" on Mount Graham and the White Mountains. Precipitation chances diminish from the west to east as the low moves out of the area into Colorado mid-day Sunday. Temperatures with this system will cool to 7-10 degrees below normal continuing through Monday. Freezing temperatures are likely for areas east of Tucson in the lower valleys Saturday morning, returning again each morning starting Monday. High temperatures however warm to around normal or just above normal through Thanksgiving as weak ridging builds in behind the low. Conditions through the upcoming work week will be drier than we have observed these last several days. && .AVIATION...Valid through 23/00Z. BKN to OVC skies AOA 15-25k ft AGL across the area. Clouds will become less covered over KDUG, KOLS, and KSAD becoming SCT to BKN by 22/11Z. Clouds will increase to BKN to OVC again by 22/22Z AOA 15-20k ft AGL. SFC winds will generally be from the southeast at 5-10 kts through 22/16Z increasing to 10-15 kts gusting 20-25 kts at KTUS, KSAD, and KDUG and up to 30 kts at KOLS. Precipitation chances begin around 22/20Z starting in KTUS expanding east throughout the afternoon into the evening. There is a slight chance for embedded thunderstorms between 22/21Z through the forecast period. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Below normal temperatures continue through the weekend with minimum relative humidities above 30 percent. The second system arrives late Friday through Saturday bringing another round of showers and high elevation mountain snow. Chances for showers remain west of Tucson through Saturday morning, then spread east Saturday afternoon and evening lingering Sunday. Temperatures below normal Sunday and Monday then rise to near normal by the middle of next week. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Malarkey Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson