Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
111 FXUS65 KTWC 051643 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 943 AM MST Sat Sep 5 2026 .SYNOPSIS... Expect isolated to scattered thunderstorms each afternoon and evening into early next week, with a potentially more active period later next week. The main threat will be heavy rainfall leading to localized flash flooding. High temperatures will will fluctuate between near normal and a few degrees below normal. && .MORNING UPDATE... Shaping up to be a pretty subdued day across SEAZ. PWAT values have dropped into the 1.0" range across the northern third of the CWA to around 1.3" Tucson Metro, with higher values up to 1.6" or so in western Pima County. Substantial moisture sits just south in northern Sonora and the northern Gulf of California. While most solutions keep the majority of the area dry, a couple CAMs do show higher end isolated to perhaps scattered showers and storms along the immediate International Border from Sasabe to Nogales to Sierra Vista. That is the only adjustment made was to bump up POPs in these areas. As you go north toward Tucson/I10 corridor, POPs drop substantially. The main threats with any storms today will be lightning, heavy rain, and gusty outflow winds. Not expecting anything severe, but could see some minor flooding from any stronger storm along the immediate International Border. && .DISCUSSION... Currently there is few to scattered clouds in Western Pima county as well as Cochise, Graham, and Greenlee counties. Over the next couple of hours, mid to high level clouds from the southwest will begin to come into Southeast Arizona. Similar to yesterday, storms will struggle to form with the mid level warming and still lack of overall lift/forcing. The only exception is in the Sky Islands thanks to orographic lifting. The latest CAMs support this as well with very limited activity this afternoon and evening. The rest of this weekend into early next week continue to look very limited, with the best chances south and east of Tucson, where the best instability is. With the above normal moisture, locally heavy rainfall leading to flash flooding continue to be the primary impacts with these storms. The low pressure system in the Pacific Northwest will have a few shortwaves pass through as the high pressure begins to slowly drift westward, shifting the flow aloft from SW to SE Monday into Tuesday. With this shift, the storm chances begin to increase in coverage across much of Southeastern Arizona in the mid to late in the work week. Temperatures will be within a couple of degrees of normal through Wednesday, then dropping to below normal levels late next week. && .AVIATION /18Z SATURDAY THROUGH 18Z SUNDAY/... Valid through 06/12Z. FEW to SCT clouds 7-12k ft AGL, mainly KTUS eastward and passing SCT to BKN cirrus clouds 20k ft AGL. Isolated TSRA/SHRA 05/18Z thru 06/03Z mainly south and east of KTUS. Near any thunderstorm will have strong gusty winds, heavy rainfall, and brief lowering of ceilings. Outside of thunderstorm winds, SFC winds west to northwesterly 6-12 kts from 05/18 thru 06/06Z. Light and terrain driven at other times. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER... Expect daily scattered thunderstorms each afternoon and evening at least into early week. There will be some variation in coverage day to day, but expect the bulk of the activity from Tucson eastward. Heavy rainfall leading to flash flooding will be the main threat. Temperatures will be around normal to a few degrees below normal into early next week. Minimum relative humidity values mainly 20 to 45 percent in the valleys and 30 to 60 percent in the mountains over the next week. Winds will generally remain less than 15 mph and terrain driven through the week. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook, X, YouTube, and at weather.gov/Tucson