Forecasters are warning residents of the Pacific Northwest that the incoming atmospheric river will increase the threat of flooding and avalanches across the region beginning this weekend. Here are the details on this volatile weather pattern.

Pacific Storm Train Chugs Along in the Northwest

A series of different storms is going to unleash an atmospheric river across the Northwest in the days ahead. The active weather pattern will persist well into the start of the new work week, bringing in loads of moisture in the form of either rain or snow.

Several rounds of moisture will push into the Northwest and the Canadian province of British Columbia from the Pacific Ocean. The first of the series arrived to the region late Wednesday, delivering heavy rainfall to Washington, Oregon, and beyond.

Another round of moisture impacted the Northwest on Friday. This system was responsible for widespread rainfall amounts of 0.50 of an inch to 2 inches across the lower terrains of western Oregon and Washington. This rainfall was in addition to the up to 2 inches that fell in the same part of the region heading into Friday.

While this has not been a major snow producer, roads have been a bit dicey at times heading over the mountain passes to end the week. Patchy fog and high winds also elevated the risk of inclement road conditions.

The most powerful of the string of storms is forecast to impact the region this weekend. Warmer air coming in ahead of the weekend event will support the development of more rain but will limit snowfall accumulation.

The plume of moisture is predicted to stretch from north of the Hawaiian islands and into the western portions of the Pacific. This atmospheric river will act as a fire hose sending mass amounts of moisture across land when it comes ashore in the Northwest.

According to the latest prediction from the Center For Western Weather and Water Extremes at Scripps Institution of Oceanography, this particular atmospheric river will be categorized as strong to extreme. The current forecast is predicting the event will come in at a 4 or 5 designation on a scale of 1 to 5.

The upcoming weekend storm system will also unleash powerful winds at times. Gale conditions are expected for much of the coastline of Washington and Oregon.