The well advertised “atmospheric river” took aim at Southern California last night and today, bringing in high levels of moisture from the subtropics. A low pressure system paired up with this moisture, and the combination has brought excessive amounts of rainfall to most areas of the state today. Flooding has been reported in many areas, with dangerous traveling conditions.
GOOD NEWS FIRST….
Thankfully, the moisture plume is advancing east, and will be leaving our area within the next few hours. Skies may become partly cloudy before sunset, with most of the heavy rain likely ending. A few scattered light showers are possible tonight and Friday (and again Sunday), but those should mostly be confined to the nearby mountains and also in the higher desert areas near Pioneertown, Morongo Valley, Yucca Valley and Joshua Tree. Widespread torrential rains are NOT expected tonight or tomorrow.
HOWEVER, in the meantime, it may take several days or more for many of the flooded washes to dry up. It will also take awhile for roads to be cleared. More on road closures in a moment.
WHAT HAPPENED TODAY?
A plume of very moist air from northeast of Hawaii combined with a potent low pressure system, which took aim directly at Southern California today. A very strong storm earlier in the week struck the Hawaiian Islands with destructive winds, high surf and even snow down below 7,000 feet. This was a rarity for Hawaii. This storm tapped into moist air from the tropics, and the air circulation patterns around the low pressure system carried the moist air to the northeast. The “perfect setup” occurred, as this moisture combined with a low pressure system moving southeast off the coast of California. This formed a relatively narrow “river” of moist air that hit Southern California, mostly between about Big Bear on the north, and San Diego on the south.
Since the air mass associated with this system originated far to our south, the snow level rose all the way up over 10,000 feet today. This meant all the precipitation fell as rain, even up most of the nearby mountain slopes. The already heavy rainfall fell atop a heavy snow pack, and added to the extreme amount of water flowing off the nearby mountains. Mt. San Jacinto has already reported over 9 inches of rain since last night, which is why the rivers flowing off the mountain are nearly overflowing.
Rainfall totals in the Palm Springs area have averaged 2-4 inches, with 1-2 inches in the Yucca Valley and Joshua Tree area, and around 1 inch in the east valley areas. Here’s a map from the National Weather Service, as of about 1 pm. These numbers will likely rise a bit as the rain is still falling in some areas. Clearly, today’s deluge hit the mountains hardest, with most areas picking up 5-9 inches overnight.
Todays extreme weather has caused major travel headaches in our region as well. As best I have been able to assess today thus far, the following roads are either closed, or have been closed at some point today:
Highway 111 at Windy Point (rockslide, between PS and I-10)
Golf Club Drive at the wash, north of highway 111 (Palm Springs/Cathedral City)
Cathedral Canyon Rd, north of Perez Rd (Cathedral City)
Frank Sinatra, just east of highway 111 (Rancho Mirage)
Country Club Dr, just east of highway 111 (Rancho Mirage)
Fred Waring, east of Portola (Palm Desert)
Indian Canyon Rd, between I-10 and Palm Springs, at the wash
Gene Autry Trail, between I-10 and Vista Chino, at the wash
Vista Chino, at the wash, just east of Gene Autry Trail (Cathedral City)
Highway 243 closed both north and south of Idyllwild. The road has been washed out in several locations, effectively cutting off Idyllwild today
Highway 74 from east of Hemet to Mountain Center and near Lake Hemet
Highway 18, west of Big Bear, due to landslides
Several roads in the Yucca Valley area have experienced closures, including Paxton Rd between highway 247 and Balsa, as well as India Ave between Barron Dr and Nelson
IMAGES FROM TODAY
Several weaker weather systems are expected to pass through Southern California the next 5 days. The next appears late Friday and Friday night, then again Sunday. Both systems are not expected to be major rainfall producers for the deserts. However, they may drop light rain at times, and may increase the winds as well. Temperatures will be chilly over the weekend, and lowering snow levels will make snowfall likely once again in the mountains. Lowering temperatures will likely lead to icing of leftover water above about 4,000 - 5,000 feet, adding to cleanup challenges in the Idyllwild and Big Bear areas.
Stay safe out there, and stay tuned to additional road closures. I’m sure the brave people employed to clear our roads will be doing their best to help return travel patterns to normal over the course of the next 7 days! They will have their hands full!