Logjam of Pacific Storms Pack Plentiful Western U.S. Weather Headaches

A logjam of Pacific winter storms will pack plenty of weather headaches across the Western U.S. until late this week. Among them is potentially life-threatening flash flooding and piles of mountain snow.

A large, slow-moving upper-level system will finally exit the Western U.S. by Wednesday night, landing in the Dakotas. Another will follow quickly behind the first, perusing the Golden State into the Four Corners for midweek and Thursday, much like its predecessor. This will lead to more valley and beaches rain and bountiful mountain snow.

Additional rainfall accumulation of one-half inch to 2 to 3 inches locally will likely lead to more urban and river, stream, and creek flooding throughout southern California near and south of Los Angeles to San Diego. Even the Interstate 10 and 40 corridors across interior southern California and western Arizona in places such as Kingman and Phoenix, Ariz., could see similar flooding woes through Wednesday evening or early Thursday morning.

Storm rainfall totals have been unbelievable. Middle FK Lytle Cree, Calif., has picked up 13.60 inches, an astonishing number in just 72 hours. Lytle Creek Raws, Calif., measured 12.20 inches so far, wither Bernina Drive, Calif., at 5,360 feet, drenched in 9.93 inches and counting. Countless southern California valley and coastal locations have been swamped by as much as 5 to 9 inches of rainfall already.

Life-threatening flash flooding will remain an issue, especially from Los Angeles to San Diego. Unstable ground due to saturated soils will lead to rock and landslides as well. If you approach a roadway covered in water, remember simple advice – “Turn Around, Don’t Drown!”

Flood Watches and Advisories remain in effect from southern California to the southern Mojave Desert and southwestern Arizona. Los Angeles, Anaheim, San Diego, and Palm Springs, Calif., and Kingman and Phoenix, Ariz., are included.

Another tentacle of the storm’s will be accumulating snow, especially from parts of the Sierra Nevada to Utah’s Wasatch Range, and Colorado’s San Juan and Rocky Mountains. Another ribbon of moderate to heavy, wet snow will occur from eastern Idaho to the U.S.-Canada border in Montana and North Dakota on Wednesday and Thursday. Several inches are expected, with 1 to 3 feet locally occurring at elevations higher than 7,500 to 9,000 feet.

Winter Storm Warnings and Winter Weather Advisories dot the western U.S. from parts of the Sierra Nevada to the Four Corners, and as far north as the U.S.-Canada border in Montana and northwestern North Dakota. Avalanche Warnings remains in effect for the Centennial Mountains in Island Park, the Lionhead area near West Yellowstone, and the southern Madison and Gallatin Ranges in southwestern Montana and northeastern Idaho. Stanely and Haley, Idaho, part of the Sawtooth Mountains, are included as well.

Plan on slippery, snow road conditions leading to difficult to even impossible travel. Heavy to very heavy snowfall rates and blowing snow will cause low visibility. Downed trees and power lines are also a concern due to gusty winds. A large amount of new snow combined with windy conditions will lead to unstable snowpack, causing concerns for avalanches.

It’s never too early to have a supply kit packed in case of inclement weather. A simple kit including a weather radio, water, blankets, batteries, and non-perishable food items will go a long way in the event of a power outage. It’s always best to avoid travel in rough weather as the roads will be dangerous.