We’re going to be tracking two new upper-level disturbances that will dive southward from the Gulf of Alaska, leading to another round of heavy snow to much of the Western US into early-next week. The first out of two disturbances will move into the Pacific Northwest on Friday.
The day will start off dry on Friday in the Northwest but as we get into the afternoon and evening, there will be an increase in moisture in the Olympics, Washington Cascades, and at times in eastern Washington State. Then overnight, the precipitation will become more widespread with rain in the lower elevations of western Washington and Oregon. Meanwhile, in higher altitude, snow is forecast to fall at a heavy rate in the Cascades. Snow is even possible in portions of the coastal range while a light snow will begin to fall in parts of the northern Rocky Mountains.
On Saturday, the moisture will continue to work further south and east. Snow is forecast to fall in the Cascades, eastern Washington and Oregon, Northern California, the northern Rockies, and northern Nevada. Snowfall rates in most of these locations will be light, falling at around half an inch per hour. Where it’s warmer, light rain showers can be expected along the Pacific Northwest coast down into Northern California. As we get into the overnight hours of Saturday, our second storms system will begin to move in from the Gulf of Alaska, while our first storm winds down. Snow showers can still be expected in the northern and central Rockies and parts of Nevada. Now with our second storm, it will bring an increase in snowfall rates as the night progresses to the Cascades and Olympics. Rain will also return by the time you wake up Sunday morning along the Washington and Oregon coasts.
This second storm will be the more potent one, and the model guidance is thinking that it will stall over California, which would be very good news for the Golden State. If that’s the case, days of rain and snow will fall. So on Sunday, very heavy snow with snowfall rates potential up to three inches per hour is expected in the Cascades. Travel will be very difficult if you’re driving through Snoqualmie Pass, for example. Snow is also forecast in portions for the coastal range and into the northern Rockies, as well as inland Washington and Oregon. Snow will persist Sunday night, especially in Oregon, while much of it clears out of Washington as the night progresses, although it will continue in all of the Cascades through Monday. Expect snow throughout much of Oregon and into Northern California. A city like Portland, Oregon may deal with a brief period of snow as the precipitation comes to an end and colder air travels in behind the storm. The snow will continue in the northern Rockies as well.
On Monday, the upper-level disturbance will begin to stall out as it drifts to the south, keeping snow around for days in some locations. Snow will slide into most of the Sierra Nevada Mountain range while continuing across Northern California, the Cascades, and the northern Rockies. Occasional snow is also possible in portions of Oregon and Nevada as well. In terms of the rain, showers will continue at times along the Northwest coast while a more widespread rain possibly moves into the Bay Area of California. Monday night, the precipitation will become more confined to the Southwestern US. Heavy snow is forecast across the Sierra and into the San Gabriel Mountains. Rain will fall across the rest of the state. Lighter snow showers will span from Northern California through the northern Rocky Mountains.
On Tuesday, the snow will continues across the mountains into California and snow will eventually move into the southern Rockies in the Four Corners States with rain showers in the lower-elevations. Of course we’ll talk in more detail about this as we get closer in time, but for now snow is possible mid-week across much of the Southwest.