A serious multi-day flood threat is underwayin the Southwest as two former tropical systems turn the typically dry desert into a breeding ground for heavy rain.
Soaking rainfall began over the region Thursday night as increasingly humid air arrived. Parts of the Phoenix metro had picked up a half-inch or more of rain by early Friday afternoon, with higher totals of 1 to 3 inches in the mountains north of there.
Flood watches cover parts of six states, with the bull’s-eye of the most serious flood concern in central and northeastern Arizona and southwest Utah now into Saturday morning. That’s where a Level 3 of 4 risk of flooding rainfall has been issued, according to the Weather Prediction Center. This means“numerous flash flooding events” are possible, some of which could be “significant,” the WPC said.
Former Hurricane Priscilla is helping to vault a record level of moisture for this time of year over the region, priming the atmosphere to produce rainfall totals from 1 to 4 inches. Combine that with the region’s mix of dry desert ground and mountainous terrain, and it’s a perfect recipe for rainfall to runoff quickly and trigger flooding…