Over a month’s-worth of rain could fall in the Desert Southwest and cause widespread and significant flooding

(CNN) — A serious flood threat is on tap for some of the driest areas of the United States as an ailing former Hurricane Priscilla combines with another storm system to create a long-lasting rainfall event.

More than an October’s worth of rain could fall within days in some areas of the Southwest and cause “potentially widespread flash flooding” and “significant impacts” as the week comes to a close, according to the Weather Prediction Center. And another tropical system following on the heels of Priscilla early next week could pile onto the flood threat.

Periods of rainfall will likely begin to increase Thursday, but the flood threat really increases Friday. A Level 3 of 4 threat of flooding rainfall is in place for Friday into early Saturday across central and northeastern Arizona, inc