Pineapple Express to soften Western OS with Rain, Snow

Days of rain are expected to hit parts of northwestern and California, which brings the risk of flooding and landslides. While the rain may fall a little faster in some places in some places, snow is expected to take its place and bring a new set of challenges, the accuweather meteorologists warn.

“A major weather event, known as a Atmospheric river, expected to unfold in the middle of next week and send waves of moisture to the west coast, ”said Accuweather Senior Meteorologist Adam Douty.

An atmospheric river is a phenomenon that occurs when moisture consolidates and raises a long distance only to be deposited somewhere else. This can happen all over the globe, but is often noted along the west coast of the United States. The funnel of tropical moisture, specifically from the central Pacific, near Hawaii, into the US is known as Pineapple Express.

Over the next week, Pineapple Express is expected to unload on the northwestern Pacific and the northern half of California, which brings the risk of flooding of rain and snow.

The winter months are typically the wettest time of the year of California and the Northwest, so the region is no stranger to rain and snow in late January and February. However, it has been abnormally dry since the beginning of 2025.

San Francisco Has only reported 0.13 of an empty rain since January 1st, when the historic average for the month is about 3.9 inches. Redding, CaliforniaHas reported 0.63 of an inch, a minuscule 10% of the norm for January. The recent dry conditions could promote the risk of flooding when heavy rain moves into the region.

Through Monday, the atmospheric river is expected to point just to the coast of northern California, which results in the largest rainy weather so far this year.

With so much rain in just a few days, there will be an increased risk of flooding. In the more mountainous terrain, landslides will also be a concern. Both floods and landslides can lead to travel delays or even road closures. Flights are also expected to be affected in view of the Multiday event of Gusty Vind and Rain.

Widespread rainfall of 1-2 inches is expected for San Francisco and Bay Area north to northwestern Oregon with over half a feet of rain in parts of northern California. A 24 -inch Accuweather Local Stormmax is probably in this area.

In addition to heavy rainfall falling in valleys, higher terrain is also expected to be affected.

“Unlike with many other winter storms in the last two years, temperatures will be too high for significant snowfall in Sierra Nevada,” Douty said.

Snow levels in Sierra will be the lowest, about 7,000 feet, into Friday night, Douty noticed, adding that the snow level will rise to almost 9,000 feet and stay there through the weekend. Snow at this high altitude is well above the pass level.

Mountains, currently covered with feet of snow, can expect several centimeters of rain, which is further raising concerns about flooding.

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Another moisture wave is expected early next week and can bring a push of colder air and the risk of snow in the higher terrain of northern California.

“Snow levels are then expected to fall early next week, which will bring potential travel impacts across the passes,” Douty warned.

The northwest Pacific will also be affected by the atmospheric river, with waves of rain and snow forecast to hit the area.

Most of the rainfall is expected on Friday night. The highest rainfall is expected in the order of 1-2 inches across the coast of Washington and Oregon.

Unlike places further south in California, the mountains of the cascades and Northern Rockies in Idaho can expect rounds with snow.

At the beginning of the weekend, most of the moisture from the atmospheric river is pushed into northern California. While heavy rainfall is expected to end up in most of Washington and Oregon at the time, it is expected that there are showers and winter conditions to continue as snow levels lower.

This weekend there will probably be a dry zone against the immediate east of the cascades. Still, some rain and wet snow can fall into eastern parts of Washington and Oregon on Saturday night and Sunday.

“Enough cold air is expected to infiltrate the northwest in time for the weekend to continued snow showers in the mountains. However, flags can also reach the lowland areas,” Douty said.

Snowflakes are possible in the big cities in Portland and Seattle When temperatures fall on Saturday night. There is even the potential for Seattle to get some accumulating snow.

Seattle has not yet had any accumulated snow this winter, but its last experienced measurable snow happened on March 3, 2024, when 0.3 inch fell.

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