The atmospheric river has reached the Pacific Northwest and moderate rain has spread over much of the area.
The steam satellite imagery is dramatic, showing a strong plume of steam moving northeast from the Pacific Ocean (see below). Looks scary, doesn’t it?
Some people rate atmospheric rivers as hurricanes and tornadoes, and they rank the event as AR4 (atmospheric river, category 4), out of 5 possibilities.
This atmospheric river has not only moisture but also strong south-southwest winds, creating a very dramatic rain streak northeast of the Olympics (see 7:30 p.m. radar image outside). below). Yellow and orange indicate the heaviest rainfall, with the southeast side of the Olympics currently seeing the worst. In contrast, from Sequim to the north of Whidbey Island, it was completely dry in the shade of rain. So if you want to go for a walk in the evening… you know where to go.
Total rainfall to date (until 7pm) is shown below. More than an inch has accumulated on the southwestern slopes of the Olympics and some favored areas in the Cascades, but only 0.01 inches on Lopez Island south of the San Juans. And people, this is just the beginning.
It’s not uncommon for a 100 to 1 precipitation ratio around here between the wet and wet side of our local terrain. We have the most rainfall in the world. Something to be proud of.
The latest precipitation forecast for 4pm today (Sunday) to 4pm Tuesday from the NOAA HRRR model predicts 5 to 10 inches in the mountains, with even heavier rainfall in the mountains. South Washington Falls. 3-5 inches above Puget Sound south. That is unusual. Urban flooding is expected.
And the NOAA/NWS River Forecast Center is still dealing with major flooding on the Snoqualmie River and moderate flooding elsewhere. There will be flooded roads at low-lying points near the river.
A major positive of this event is that heavy rain will fall on far east Washington, help restore soil moisture to dryland farmers there (see rainfall totals for the event below). The strength and direction of this atmospheric river is well structured to carry moisture into eastern Washington. Very good news.
