PORTLAND, Ore. (KOIN) — As the Portland metro area sets itself up for a relatively calm and pleasant first full week of fall, areas just to our north in Washington and Southern British Columbia are preparing for a low-end Atmospheric River event currently taking shape over the Pacific as of Monday afternoon.
By Monday evening and Tuesday, a narrow band of water vapor in the upper levels of the atmosphere will arrive in parts of southern British Columbia and Vancouver Island. Latest model guidance indicates anywhere between 1.5 and 2.5 inches of rain are expected for Vancouver Island and the British Columbia Coast.
In Northern Washington, forecast models indicate that as high as two inches of rainfall are forecast for the elevated areas of the Olympic National Forest, including the town of Forks, Washington, along the coast. Lighter amounts will extend inland over Washington. However, areas near Bellingham, WA, could also see upwards of an inch of rainfall before the system weakens on Wednesday.
The Portland/Vancouver metro area will likely see nothing more than increased clouds on Tuesday and a chance of sprinkles along the coast and into Northwest Oregon and Southwest Washington on Tuesday as the system passes by just to our north. Temperatures will remain in the upper 60s and lower 70s this week across the metro area.
Later in the week, a weak ridge of high pressure will again rebuild over the area, bringing patchy morning fog and low clouds followed by plenty of afternoon sunshine and temperatures around normal for this time of the year. The average high temperature at the Portland Airport is approximately 72 degrees for late September…