Pacific Northwest Readies for Another Round of Precipitation

Posted: September 24, 2021 11:03 am

After a week of relatively mild weather conditions in the Pacific Northwest, a new rain system is setting up to take aim at the region by the end of the weekend. There will also be another round of rain in store for the Southwest.

Northwest in Crosshairs for More Rain

Some parts of the Northwest saw their most significant precipitation in months last weekend when a moisture-rich storm system pushed in from the Pacific Ocean. While this system helped to slightly alleviate the ongoing drought conditions, another bout of precipitation is on its way.

A ripple in the jet stream will be the culprit for this new round of rain. This is welcome news for both the Seattle and Portland regions, areas that have seen precipitation levels far below normal dating back to last spring. According to the latest data from the US Drought Monitor, over 70% of Oregon is under extreme drought conditions. Washington is faring slightly better with 45% of the state in the middle of an extreme drought.

What is in Store for Pacific Northwest

The next storm system is forecast to drop between 0.50 of an inch to 1 inch of rain to the lower elevations stretching along the Interstate 5 corridor that connects Seattle to Portland. However, the west-facing slopes of the Olympic and Cascade mountains may see up to four inches of rain by the time this major rainmaker is done.

It was the coastal areas that saw the most rain from last weekend’s rain. This is likely to be the case again with this rain event.

Just like last week’s system, this event will also bring the chance for the first snow of the season to some of the higher terrains. This upcoming system may bring an even greater chance of snow to these elevations.

Western Washington will see the first of the rain starting on Sunday. This rain will then move into the northwestern corner of Oregon before pushing farther to the east. By the time Monday rolls around, the light precipitation of Sunday will evolve into heavier downpours as a cold front comes in from the Pacific. Colder air and gusty winds will move in behind the front, creating a blustery start to the week.

The arrival of this cooler air will also increase the chances of snow in the higher elevations. The stronger winds are expected in the coastal areas and up in the mountains.

The snow level is forecast to be at about 6,000 feet or above. This elevation is higher than the mountain passes of the Cascades, meaning that motorists should see fair travel conditions this week.

The rain will begin to dissipate by the end of Tuesday as the bands of precipitation continue to move farther to the east. By the middle of the week, this storm will be making its way into the central Rocky Mountains.

Stormy Start to Weekend in Southwest

Meanwhile, the Desert Southwest will be dealing with a stormy start to the weekend. A round of severe thunderstorms is in the forecast for the Southwest beginning on Friday. However, this thunderstorm activity is unlikely to produce any rain of significant amounts. Instead, it may just increase the risk of lightning strikes to fuel more wildfires in the drought-stricken region.

The storms will fire up as the jet stream plunges southward into Nevada, Utah, and Arizona on Friday. This threat of severe weather will continue through the weekend as the jet stream maintains this position.

While the greatest risk of dry lightning will be in Southern California, the threat of severe weather will stretch as far north as the Sierra Nevada. This area of California is still struggling to try to get fires under control.