Arizona and Southwest Flash Flood Outlook, Oct 30–Nov 1, 2026

Observed rainfall

No observed rainfall total is on file for this event yet.

Outlook

The damage map keeps National Weather Service flood and heavy-rain reports for central and southern Arizona, southern Utah, New Mexico, southern Nevada, and southern California, inside the stored search area. Phoenix, Tucson, Yuma, Las Vegas, Albuquerque, Los Angeles, San Diego, and Palm Springs are the tracked markets in that area. The dates run from Friday, October 30, through Sunday, November 1, so the excessive-rainfall outlooks for those days stay on this page. The Weather Prediction Center excessive-rainfall discussion and the Storm Prediction Center convective outlook on this page are the latest stored products, replaced on each collect. Tornado, hail, and wind reports for Arizona stay on the Arizona severe storms page.

Arizona severe storms. Tornado, hail, and wind reports for Arizona are on that page.

Damage map

Latest outlooks

Weather Prediction Center

Excessive rainfall discussion, 1141 AM EDT Thu Oct 29 2026.

Day 1 Valid 16Z Thu Oct 29 2026 - 12Z Fri Oct 30 2026 MO/KS/IA/NE irregular border junction... A warm front at 850 hPa lifts northward, with a pool of instability in its wake. Precipitable water values rise to 1.25" or so. The 12z HREF shows a backbuilding convective scenario unfolding from 04z onward, and shows the probabilities of 3"+ maximize in a point near the NE/MO/KS border junction. The 12z REFS has a milder signal somewhat displaced to the southwest, which is counter its traditional bias. There's enough going for it for add a Marginal Risk. Flash flooding would be most likely in urban areas, where 1.5" in an hour is possible.

Day 2 Valid 12Z Fri Oct 30 2026 - 12Z Sat Oct 31 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF CENTRAL AND SOUTHERN ARIZONA... ...Southwest... Broad troughing will develop over the West with embedded shortwave energy moving across portions of the Southwest on Friday. Meanwhile, a strong southern stream jet will approach Baja California, placing Arizona under the favorable left exit region with enhanced upper level divergence Friday afternoon. Southerly low-level flow will direct Pacific moisture into the area as well, bringing PWATs up to 1-1.4 inches across the southern half of Arizona (2-3 standard deviations above normal). This warm, moist air mass will also increase instability, with MUCAPE values forecast to reach 700-1000 J/kg across much of southern Arizona. With favorable conditions throughout the atmospheric column, scattered to widespread convection is expected to develop with the passing of the upper shortwave Friday afternoon and evening. Deterministic and ensemble model guidance continues to show elevated rainfall totals along and south of the Mogollon Rim where there is a Slight Risk of excessive rainfall. Available hi-res and global models forecast rainfall rates exceeding 3hr FFGs (1-2 inches) across central and southern Arizona on Friday afternoon and evening. Both the HREF and REFS show moderate probabilities (30-60%) of 6hr QPF exceeding 2 inches and precipitation exceeding FFGs. Given the sensitive terrain in the area and relatively moist soils across central and southern Arizona, this setup will likely produce scattered instances of flash flooding. A broader Marginal Risk area surrounds the Slight and includes portions of southern Utah and New Mexico where there will also be scattered convection, but the flash flood risk will be more isolated as rainfall rates are less likely to exceed FFGs.

Day 3 Valid 12Z Sat Oct 31 2026 - 12Z Sun Nov 01 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF CENTRAL AND SOUTHERN ARIZONA... ...Southwest... A deep upper level trough/low will move over the West Coast on Saturday, sweeping up a potent Pacific shortwave and directing it into the Southwest by Saturday evening. This system will be accompanied by an amplified southern stream jet that will enhance divergence over portions of the Southwest Saturday evening into Saturday night. Ahead of the system, a stream of subtropical moisture will increase PWATs above 1 inch across southern California, southern Nevada, and Arizona, and even above 1.5 inches for portions of central and southern Arizona. These values are highly anomalous (4-6 standard deviations above normal) for this time of year and should support widespread precipitation as the shortwave moves onshore. CAPE will be the limiting factor in this scenario, with cloud cover keeping MUCAPE to only a few hundred J/kg over portions of central and southern Arizona with little to no CAPE elsewhere. Given this setup, locally heavy rainfall will be possible across much of the Southwest, but rainfall rates may be limited outside of favorable locations in Arizona where there is a Slight Risk of excessive rainfall. Portions of Arizona will also see heavy rainfall on Friday, which may increase the sensitivity to flash flooding with additional rainfall through Saturday night. There is still some uncertainty in the timing of this system, the GFS is notably slower than other deterministic (physical and AI) models, but the WPC forecast favors a faster solution that is closer to the general model consensus. This event will continue into Sunday, and conditions are expected to become more conducive for a widespread heavy rainfall event across the Southwest.

Day 4 and Day 5 Valid 12Z Sun Nov 01 2026 - 12Z Tue Nov 03 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTHWEST SUNDAY... ...Southwest to Plains/Mississippi Valley... A potentially high impact setup remains possible over the Southwest on Sunday. A deep longwave upper trough will be located over the West Coast early Sunday, while an anomalously far south southern stream shortwave tracks toward/into southern California/northern Mexico while carrying a surface low pressure system, with these features merging later Sunday. The combining features will bring strong forcing to the Southwest, including the right entrance region of the upper jet. Moisture-wise, IVT anomalies start to max out (for this time of year) in southern Arizona and vicinity Sunday per the NAEFS Ensemble Situational Awareness Tables, as strong and deep level Pacific moisture takes aim at the region. Widespread moisture and cloud cover may limit instability a bit, but at least a modest level of instability is forecast to develop, given the strong troughing aloft should steepen lapse rates. Soil moisture remains rather wet in most areas due to heavy rain over the past days and weeks, increasing the flooding threat hydrologically. All this, plus potential terrain enhancements to rainfall, yields what is considered a higher-end Slight Risk across the Southwest on Sunday. Moderate Risk level impacts are possible and this potential will continue to be monitored in future forecasts. A broader Marginal Risk expands west through southern California and east across much of New Mexico.

Storm Prediction Center

Day 2 convective outlook, 1229 PM CDT Thu Oct 29 2026. Valid 301200Z - 311200Z. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF SOUTHERN AND CENTRAL ARIZONA Isolated strong to severe thunderstorms are possible across portions of southern/central Arizona on Friday. Damaging wind gusts and large hail will be possible with the strongest storms.