Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
949 FXUS65 KTWC 302203 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 303 PM MST Fri Oct 30 2026 .SYNOPSIS...Scattered showers and thunderstorms will persist into this evening. Saturday will see a lull in precipitation, though isolated showers persist. Another weather system will bring widespread showers, heavy at times, with scattered thunderstorms Sunday into Monday. A Flood Watch is in effect for all of southeast Arizona from 11 PM Saturday through 5 AM Monday. && .DISCUSSION...We`ve had several periods of showers and thunderstorms moving across the forecast area today associated with a upper level trof that was along the Colorado river this afternoon. Rainfall amounts so far today, as of 2 pm, have ranged mostly less than 0.40" with isolated totals up to 0.75". Latest CAMs keep activity going late into the evening and if we see some breaks in the clouds to get some additional destabilization before sunset, a few storms could briefly get frisky with severe wind/hail and brief heavy rain and localized flooding concerns. Saturday: Moist southwest flow aloft continues and although the area will be in between systems, isolated showers will be around producing light rainfall amounts. Late Saturday night into Sunday night: A strong southern steam system, riding the subtropical jet, will be approaching the area late Saturday night as the west coast upper level trof moves inland. A strong atmospheric river (AR), level 3 on a AR 1-5 scale, will bring near record to record levels of PWAT of (1.25" to 1.50") for November. As this AR moves over the area, expect widespread moderate to localizes heavy rain and isolated embedded thunderstorms on Sunday. Upslope flow into the mountains will enhance rainfall rates/totals. Most of the area is under slight risk from WPC for excessive rainfall with a very small snippet of far northern Graham and Greenlee counties under moderate risk. We are looking at rainfall records for November 1st falling across much of the area. A Flood Watch is in effect for all of SE AZ from 11 pm Saturday to 5 am Monday. What is uncertain is how much rainfall Sunday into early Monday. Below is a look at the expected totals, high and low end totals. Expected: Valleys 0.50"-1.50", Mountains 0.50"-2+" Low end (9 in 10 chance): Valleys 0.10"-0.90", Mountains 0.30"-1.5" High end (1 in 10 chance): Valleys 1.75"-2.75", Mountains 2"-4" locally higher With the expected rain on Sunday into early Monday we will see a response in the area rivers, creeks and washes across SE AZ. See hydrology section below for further details. Thereafter, we`ll get into a quieter weather regime early next week. Any lingering precipitation should come to an end Monday morning with shortwave ridging and dry conditions Tuesday and Wednesday. Thursday still looks dry as well, then more uncertainty thereafter as another system potentially impacts our area next Friday and beyond with more precipitation chances. Daytimes temperatures will mostly be below normal through the forecast period, with the coolest highs Sunday and Monday. && .AVIATION...Valid through 01/00Z. BKN clouds 7-10k ft AGL thru valid pd. SCT-NRMS SHRA and SCT -TSRA through 31/06Z, then isolated activity to end valid pd. Brief MVFR conds nr showers/storms. SFC winds mainly SELY/SLY 6-12 kts thru fcst pd, with gusts 15-20 kts. Gusty and erratic winds also possible near any thunderstorm. Outlook btwn 01/06z and 02/00z, widespread MVFR conds, isold IFR conds, due to CIGS, SHRA and VSBY. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Scattered to numerous showers and thunderstorms today as weather system impacts the region. A brief break between weather systems Saturday with only isolated showers, then then widespread showers with isolated thunderstorms Sunday into Monday. Moderate intensity rainfall with pockets of heavy rain is expected today and Sunday, with locally heavy storm total rainfall amounts possible, especially in the higher terrain. Afternoon high temperatures will lower below normal through the forecast period. Breezy southerly winds are anticipated today, with breezy to locally windy southwest winds expected Sunday, turning northwest Monday. Minimum RH levels today into early next week, with values at 40+ percent. && .HYDROLOGY...As mentioned in the discussion section above, with the expected moderate to heavy rain on Sunday into early Monday we will see a response in the area rivers, creeks and washes across SE AZ. There is the potential for significant rises on the San Francisco, Blue, Gila and Sabino Creek with Minor to Major flood stages possible. This will continue to be evaluated over the next 24-36 hours. && .CLIMATE...Below is a listing of probability of exceedance of 36-hour rainfall totals from 5 pm Saturday Oct 31 to 5 am Monday Nov 2. Chance of seeing more than 1" 2" 3" Tucson 83% 40% 2% Marana 85% 31% 3% Mount Lemmon 92% 71% 13% Ajo 60% 13% 0% Picacho Peak 88% 34% 3% Oracle 92% 53% 6% Hannagan Meadow 96% 75% 10% Safford 71% 24% 0% Clifton 84% 37% 1% Willcox 67% 8% 0% Douglas 35% 4% 0% Sierra Vista 46% 8% 1% Nogales 79% 31% 4% Tucson rainfall records October 31st: 0.44" in 1926 November 1st: 0.42" in 1987 November (one-day): 2.09" on November 22, 1931 && .TWC WATCHES/WARNINGS/ADVISORIES... Flood Watch from Saturday evening through late Sunday night for AZZ501>515. && $$ Visit us on Facebook, X, YouTube, and at weather.gov/Tucson