The National Weather Service in Portland has issued a forecast indicating a trend toward cooler temperatures and beneficial rainfall across the Pacific Northwest this week. A series of frontal storm systems are set to move into the region, bringing much-needed rain and high mountain snow.
Dense Fog Advisories have been issued for the coast and lower elevations, with visibility dropping to 1/4 mile or less in some areas. While inland fog is expected to lift by late morning, uncertainty remains about whether coastal fog will clear, with probabilities for fog returning tonight exceeding 60%.
Inland high temperatures today will reach the mid to upper 70s, similar to yesterday. However, as clouds move in ahead of the first frontal system, temperatures will drop by 3-10 degrees starting Monday. Light rain is expected to begin along the southern Washington and northern Oregon coast by mid-morning and spread southeast into the valleys by evening.
The forecast anticipates a more significant frontal system to arrive Tuesday into Wednesday, potentially bringing over 1 inch of rain to inland valleys and higher elevations. Snow levels are expected to drop to 4000-4500 feet in the Cascades, with the first snowfall of the season predicted, although snow accumulation will likely remain modest.