The weekend forecast across Arizona, including Phoenix, is looking stormy with the arrival of Tropical Storm Rachel early Sunday morning. Moderate to heavy rainfall, isolated thunderstorms and gusty winds are expected, which could lead to localized flash flooding and blowing dust, respectively.
Alerts are in place
Since Friday morning, Oct. 9, local weather service offices have scheduled various alerts to go into effect as soon as Saturday, Oct. 10.
A flood watch will be in effect from 11 a.m. Oct. 10 through 5 a.m. Oct. 12 for Mojave, Yavapai, western Coconino, northern Gila and far southern Navajo counties. They cite excessive runoff possible in rivers, creeks, streams, and other low-lying and flood-prone locations. This also includes urban flooding.
The Weather
Prediction Center has placed western Mohave County under a moderate risk (40%) for flash flooding on Sunday, Oct. 11, while the western half of Arizona faces a slight risk (15%). The forecast indicates numerous to scattered flash floods are possible across these areas.
A wind advisory will cover nearly the entire state, with Graham, Greenlee and Cochise counties the only exceptions. Sustained winds of up to 35 mph and gusts reaching 55mph are forecast in various parts of Arizona. The timing varies by area on Sunday, Oct. 11:
- Maricopa, northern Pinal, southern Gila counties: 8 a.m. to 5 p.m.
- Eastern Pima, Santa Cruz, southeastern Pinal counties: 7 a.m. to 11 p.m.
- Western, central Pima, southwestern Pinal counties: 2 a.m. to 11 p.m.
- Yuma, La Paz counties: 2 a.m. to 5 p.m.
- Yavapai, Coconino, Navajo, Apache, northern Gila counties: 8 a.m. to 8 p.m.
- Mojave County: 5 a.m., Oct. 11 to 5 a.m., Oct. 12
Similar flood and wind alerts are in effect across southeastern California, southern Nevada and western Utah. Meanwhile, San Diego is under a tropical storm watch for only the second time in its history, the first being ahead of Hurricane Hilary in 2023.
The Storm Prediction Center has placed parts of central, southern and western Arizona under a marginal risk for severe storms. The primary risk is gusty winds, but the isolated tornado cannot be fully ruled out if all the perfect conditions fall into place. There’s a high amount of instability, moisture and rotation associated with this cyclonic system, so that level of convection will be watched.
So when will the rain come?
Stormy weather is expected across Arizona from Saturday afternoon through Sunday morning, Oct. 10–11, marking the best chance for rain through Tuesday, Oct. 13. The remnants of Rachel will bring scattered showers and storms during this period, followed by a brief lull late Sunday into Monday. By then, the former cyclone is expected to have moved out of Arizona, while a broader low-pressure trough could generate another round of scattered showers and storms on Monday andTuesday.
How much rain will fall?
Forecasts are ever-changing due to variations in the track forecast for Rachel. Rainfall estimates in metro Phoenix have fallen slightly since earlier in the week: now anywhere from a quarter of an inch to 1.50 inches are possible, along with some locally higher amounts. Those to the north are in higher favor through the five-day period.
The heaviest rainfall is expected in northern Arizona, particularly across Yavapai, Coconino and Mohave counties, where 1 to 3 inches of rain are possible, prompting flood watches.
Will it finally cool down?
Temperatures are expected to drop significantly next week. Highs on Saturday, Oct. 10, will reach the lower 90s before falling into the lower to mid-80s Sunday and Monday. By Tuesday and Wednesday, Oct. 13–14, temperatures could dip into the upper 70s before gradually returning to seasonal highs near 90 degrees.
Meteorologist Tevian Whitehurst covers extreme weather and climate for The Arizona Republic and azcentral.com. Follow him at @TevianWX on Instagram and Facebook (Meteorologist Tevian Whitehurst).
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This article originally appeared on Arizona Republic: Tropical Cyclone Rachel is nearing Arizona. When can you expect rain?
