CASA GRANDE — An atmospheric river will continue to deliver a plume of moisture into parts of the West, enhancing rain and snowfall totals in Arizona this week.
Following a delayed start to the wet season in fire-ravaged California, the switch has been turned on as a series of storms continues to douse the Golden State. Soon after a storm over Northern and Central California winds down, a new plume of moisture, or an atmospheric river, will unleash heavy rain and high country snow over Arizona at midweek.
The storm is not expected to unleash the equivalent of the late-November blast of rain and snow; however, it is likely to cause travel disruptions in many locations and perhaps more serious problems in others.
Snowfall with the storm from Tuesday night to Wednesday night will generally be limited to elevations above 6,500 feet over much of Southern California and Arizona.
High snow levels can present a problem following a heavy snowfall, according to AccuWeather Meteorologist Randy Adkins.
“The higher snow levels throughout the region will mean that rain will eat into some of the snowfall over the intermediate elevations in Southern California and Arizona in particular,” Adkins said.
The combination of rain, rising temperatures and melting snow can lead to flooding along some of the small streams and short-run rivers flowing out of the mountains.
There will be enough rain to cause localized flash flooding in desert and urban areas.
The bulk of the rain will fall on Las Vegas during Wednesday afternoon and evening with the wettest part of the storm due to be Wednesday night around Phoenix.
AccuWeather meteorologists warn that motorists should never attempt to drive through flooded areas as the water may be much deeper than it appears. A foot of flowing water can cause lightweight vehicles to lose traction and can swiftly carry them downstream into deeper water. Flowing water can also disguise a roadway that has been washed away.
Tragedy struck in Arizona over the Thanksgiving holiday as a truck with young children as passengers was swept away while attempting to cross a flooded creek.
Since the last rainstorm was only a few days earlier, some of the hillsides may quickly become unstable with a fresh dose of drenching rain. As a result, the potential for mudslides and other debris flows may be higher with this storm, compared to that of last week. This is especially the case for burn scar locations, but the threat will not be limited to fire-charred areas.
Meanwhile, the system moving through is potent enough to produce a few thunderstorms, some of which may be capable of spawning small hail and gusty winds.
The region will get a break from storms during the latter part of this week. However, a new storm forecast to roll ashore in Northern California and the Northwest is likely to bring showers this weekend.
Alex Sosnowski is an AccuWeather senior meteorologist.