A week ago, Hurricane Norbert pumped tropical moisture across the U.S. Southwest, touching off record rainfall in Phoenix and Tucson that killed at least two people, flooded hundreds of homes and shut highways throughout the region.
This week, Hurricane Odile moved onto the Baja California peninsula after becoming the strongest system since 1967 to hit that part of Mexico, the U.S. National Hurricane Center said.
While it isn’t time to get the rowboat out again for the morning commute, the earth in the desert Southwest doesn’t absorb water very well, the way a Florida swamp or Louisiana bayou might. A lot of rain can be far more unpredictable.
There will almost certainly be some flooding from Odile across Arizona to West Texas by tomorrow, according to the U.S. Weather Prediction Center.
The major difference between Odile and Norbert will be in how fast the rain reaches the U.S., said Charlotte Dewey, a National Weather Service meteorologist in Phoenix.
With Norbert, all the rain fell in just a few hours. Phoenix set a record with 3.3 inches (8.4 centimeters) in a single calendar day, she said. The previous single-day mark was 2.91 inches on Sept. 4, 1939.
The moisture Odile is sending north will be spread across several days. The forecast for Phoenix is for a chance of thunderstorms through the end of the week. Tucson faces a mix of thunderstorms and showers as well.
The predictions don’t mean a thunderstorm won’t set up over a city and drench it with a downpour to rival last week’s deluge. The problem is, no one can predict that, Dewey said.
In other parts of the country, 3.3 inches may not sound like much. People in New Orleans and Florida might even consider a rainfall like that a sunny day.
“Any smaller amount of rain can cause flooding here,” Dewey said.
The prediction center’s projection is for as much 3.2 inches over seven days in parts of eastern Arizona and western New Mexico.
Since Oct. 1, the start of the “water year,” Phoenix has received 8.11 inches of rain, according to the weather service.
That means almost 41 percent of the all the rain that fell this year came in a single day.
“Almost half a year’s rain in a matter of hours is significant,” Dewey said.
So if the forecast holds and the remains of Odile creep across northern Mexico, it may be good to keep an eye on the sky. And keep that rowboat handy.