Rare tropical disturbance in the Gulf of California to enhance substantial Southwest flood threat
A tropical disturbance in the Gulf of California is enhancing the substantial flood threat in the Southwest.
Monsoon storms target the Southwest US this week
Arizona, New Mexico, and portions of Utah are targeted for monsoon storms expected to bring heavy rain and thunderstorms, triggering a flood threat for many residents until Friday.
THE TAKEAWAY
- Monsoon-fueled storms will trigger heavy rain and flooding.
- A Level 2 out of 4 flash flood threat is in effect for Arizona and New Mexico this week.
- There will be an increased tropical influence due to the area to watch, which is in the Gulf of California.
Heavy rain is on the way for people in the Southwest U.S. as a tropical disturbance enhances monsoon-fueled floods in the region.
As a massive heat dome hovers over the Central and Eastern U.S., it will act like an atmospheric wall, locking in relentless monsoon weather conditions along its western edge, according to the FOX Forecast Center. The monsoon season usually lasts until the end of September.
This setup will bring a surge of tropical moisture over Arizona and New Mexico, triggering widespread thunderstorms and a Level 2 out of 4 flash flood threat until Friday.
Airflow around a high-pressure ridge to the east will continuously pump tropical moisture out of the Pacific, while upper-level energy drifting around the western edge of the heat dome will provide steady atmospheric lift.
With this moisture plume locked in and nowhere to go, persistent storms will fire up every afternoon through Friday.
As a result, Flood Watches are in place for southern Arizona and western and southern New Mexico until Wednesday.
Watch: Monsoon thunderstorm blasts Apache Junction, Arizona
Monsoon thunderstorm blasts Apache Junction, Arizona on Thursday, August 20, 2026.
The flood threat also bleeds into Utah, including the iconic Zion National Park.
These alerts include popular cities such as Phoenix, Tucson, Arizona, and Ruidoso, New Mexico, where the rain will not let up until Friday, with expected totals of around 1 to 2 inches and possibly 2 to 3 inches for some higher-elevation areas.
On top of this, there will be an increased tropical influence due to the area to watch, which is currently in the Gulf of California.
Tropical disturbances in the Gulf of California are relatively uncommon and have a low chance of becoming a named storm or depression, according to the National Hurricane Center.
LOCAL EMERGENCY DECLARED IN CALIFORNIA BEACH CITY TO STABILIZE COASTAL BLUFFS AHEAD OF SUPER EL NIÑO
As this moves onshore into Mexico on Wednesday, its moisture will surge northward into the Four Corners region and increase the coverage of widespread showers and storms.
As these storms bring repeated rainfall over the next few days, the overly saturated soil will not be able to absorb much precipitation and flooding will likely follow.
"Storms will produce high hourly rain rates, driving a persistent risk for severe flash flooding, rapid runoff into desert arroyos, mudslides in steep terrain and dangerous debris flows over recent burn scars across both states through the week," the FOX Forecast Center said.
Monsoon rain can often trigger mudslides, which makes this flood threat even more dangerous and worth monitoring throughout the week, as conditions could change or worsen.