A quick-hitting series of Pacific storms will bring rounds of rain, heavy wet mountain snow, potentially damaging waves and gusty winds to the West well into next week.
Happening now
These storms systems, fueled by an atmospheric river, will bring in widespread rain, high elevation snow and gusty conditions.
(MORE: What is an atmospheric river?)
Below is where the heaviest rain and mountain snow are ongoing.
When will the rain and snow happen out West?
This rain and mountain snow will come in waves as each of these storms move onshore. Lets break down the timings, and a graphic for each day is below as well.
These are subject to change, so check back with us often as this section gets updated:
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Sunday: By Sunday morning, the heavy rain and high elevation snow will be hitting parts of Washington, Oregon and Northern California. By the evening, it will spread from the Bay Area to western Montana.
The snowfall at this point will only reserved for the highest peaks and to not exceed a foot as this round of moisture brings slightly above average temperatures with it. Rainfall will likely reach 1-2 inches, with the highest rainfall expected along the foothills.
Monday: By Monday, the rain and mountain snow will shift to the Intermountain West. The evening brings an increased chance of higher elevation snowfall, including the Sierra Nevada and Rockies.
There is even a chance of rain from Southern California, but it is not more than an inch. The Southern Sierra Nevada should see a snowfall total between 1-2 feet by the end of the day Monday.
Tuesday: This round of rain and snow will continue its trek east as another storm approaches the West Coast. The soils along the coast will be softened up from the earlier rounds of rain from storms, so flooding potential is greater than the weekend.
Mountain snow chances will also ramp up as cooler air will be settling in, so another shot of snow for the Sierra Nevada and also the Cascades is expected as the sun goes down.
The initial rain and mountain snow will spread from the Four Corners to Montana, with rain, snow and a slushy mix also possible.
Wednesday: The next storm will be approaching its ‘landfall’ near Northern California, so the bulk of the heavy rain and mountain snow will be focused across the Sierra Nevada. Temperatures will remain below average, so the snow level in the mountains will be lower in elevation. Snow is also expected across the Intermountain West again by the evening.
How much rain and snow is happening out West?
Rainfall totals are expected to range from 3-6 inches in southern Oregon, far Northern California, in the northern Sierra Nevada foothills and on Washington’s Olympic Peninsula. Lower rainfall totals over an inch are likely from the Bay Area to western Washington and Oregon.
Given that this is the first stronger storm system of the season, flooding is not expected and the rainfall will largely be beneficial. Later storm systems may increase chances of flooding, particularly near wildfire burn scars, where mudslides and debris flows become a greater threat.
This won’t be the craziest snowmaker for the Sierra Nevada, but snowfall totals over 2 feet are possible by the end of the week.
Travel through the Sierra will be very difficult with high snowfall rates and low visibility. Strong winds will further complicate plans. Skies will clear there during the day Saturday.
The next storm will sweep southward through much of the West Coast on Sunday.
(MORE: Why snow differs on the slopes in the Rockies, Sierra and Northeast)
Where are the biggest waves on the West Coast?
There is also the element of the massive waves, which are dangerous for coastal communities and beach erosion.
- Through early Sunday: Perhaps the most potent of these storm systems could bring waves as high as 30 feet in nearshore waters, potentially breaking to 50 feet at favored spots. These highest waves are most likely from Northern California to the Oregon coast.
- Into Monday: Slightly less potent, but widespread heightened wave activity across much of the West Coast.
- Middle of next week: A smaller storm system could bring in another chance of heightened waves.
The risk for rip currents and sneaker waves will be higher than average through early in the week ahead. The risk of drowning in coastal waters is very high this weekend.
(MORE: When do larger winter storms usually start in the US?)
Boating is also ill-advised this weekend. “Mariners are urged to remain in port during this period of extremely dangerous weather, secure vessels and continue to monitor forecasts for updates,” said the National Weather Service in Medford, Oregon, on Thursday morning.
High tides combined with the elevated water levels from El Niño could create multiple feet of coastal flooding during each of these storms.
Coastal debris, including logs from evergreen trees, could become projectiles in cresting waves during these storms. This debris has killed and seriously injured people on the beaches in the past, according to the National Weather Service in Portland, Oregon.
(MORE: Super El Niño nears record strength)
Jonathan Belles has been a digital meteorologist for weather.com for 10 years. His favorite weather is tropical weather, but also enjoys covering high-impact weather and news stories and winter storms. He’s a two-time graduate of Florida State University and a proud graduate of St. Petersburg College.
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