Pacific Northwest Already Seeing Impacts of Full Plume of Moisture

Posted: April 9, 2023 9:15 am

A fresh surge of moisture is moving into the Pacific Northwest on Sunday and Monday, bringing more rain and snow to Washington, Oregon, and the northern tier of California. Read on for all of the details of this soggy forecast for this corner of the country.

Pacific Northwest Will See Wet Conditions While Rest of the West is Dry

The Pacific Northwest will be the outlier for weather this week when compared to the rest of the West Coast. The jet stream will see a classic northward bulge throughout California, Nevada, and Utah, keeping the Desert Southwest dry for the next several days. However, the other side of the jet stream will be under the gun for persistent moisture through at least the middle of the week.

The rain has already started across much of Washington thanks to an area of low pressure that is moving down from Alaska and British Columbia into the U.S. The frontal boundary of this weather feature will continue to push into the Pacific Northwest on Monday, ushering in snow in the higher terrains and rain in the lower elevations to start the new work week.

The precipitation is forecast to lighten in intensity by the latter part of the week in the Northwest. However, some showers and light snow may linger through Friday as additional areas of low pressure swing through the area. The moisture toward the end of the week is predicted to be lighter than what the region will see beginning Sunday.

Weather Impacts to Expect

This rain will bring a number of potential weather impacts to the region, including localized flooding, rockslides, and rising creeks. You will want to stay alert to the developing weather conditions if your community is prone to these risks during times of heavy rainfall.

Despite its reputation of being consistently wet and dreary during the winter, many pockets of western Washington recorded lower than usual rainfall totals in the months of January, February, and March. When taken together as a unit, the Washington cities of Olympia, Tacoma, and Seattle only saw 54% of its historical average of rainfall for these three months. April has already been significantly wetter when compared to the winter season.

The month of April has also seen unseasonably cooler temperatures for this part of the U.S. Most cities in western Washington are trending about 5 degrees below normal for the early weeks of April. For instance, the mercury will struggle to get out of the upper 40s in Seattle for the next few days. A lack of sun will make it feel even chillier.

While the Northwest is dealing with cooler weather, areas to the east will be enjoying a dramatic warmup in the coming days. Temperatures will surge to around 15 degrees above normal for cities in the Intermountain West, including Salt Lake City and Denver. The warm-up will feel particularly nice for Salt Lake City after the area at the base of the Wasatch Mountains saw readings in the 30s early last week.

The warmer weather will be a welcome respite from the cold for most people. However, the rise in the mercury will translate to an increased risk of flooding as snow begins to melt rapidly.

The bulk of the moisture to start the week will be confined to the coastal areas of the Northwest. But this does not mean that the interior portions of the region will not be under the threat of flooding. The massive amount of snowpack in this region will begin to melt at a fast clip as temperatures climb.

This threat of flooding will spread through the central U.S. and into the Great Lakes. It does not take much snowmelt from the foothills to trigger rising rivers and streams. This rise also raises the risk of ice jams, further elevating the flood threat.

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