Warm Temperatures Prevail in the Pacific Northwest Ahead of Rainy Weather

On Monday, a weak surface front is anticipated to move through the Pacific Northwest, with uncertainty in timing.Photo byElena KuchkoonUnsplash

As the weekend unfolds, the National Weather Service (NWS) in Portland, Oregon, forecasts above-normal temperatures across the region through Monday. However, a weak front moving through southern and central Oregon is expected to bring a slight chance of rain to Lane County, eastern Linn County, and the central Oregon Coast today, with minimal rain accumulation anticipated.

Current satellite imagery reveals that an upper-level closed low is approaching the southern Oregon and northern California coast. This system has already brought precipitation to southwestern Oregon, with mid to high-level clouds streaming northward into northwest Oregon and southwestern Washington. Despite high clouds lingering yesterday and keeping temperatures a few degrees cooler than expected, the forecast suggests that temperatures will rebound today, reaching the mid to upper 70s across the inland valleys and mid to upper 60s along the coast.

While there remains a 10-25% chance of isolated showers in the aforementioned areas, any rain that does occur is expected to be light, accumulating only a few hundredths of an inch due to limited moisture and evaporation as rain falls.

Looking ahead, shortwave high pressure is expected to build behind the low tonight, bringing calmer weather for Sunday. This will lead to the deepening of the marine layer overnight, with a 15-25% chance of drizzle along the coast. Inland temperatures will remain similar to Saturday's forecast, while coastal temperatures are expected to cool into the low 60s.

On Monday, a weak surface front is anticipated to move through the Pacific Northwest, with uncertainty in timing. Ensemble guidance indicates that the front may not reach Astoria until late Monday morning and the Portland metro area until late afternoon or early evening. While temperatures are expected to fall a few degrees due to incoming cloud cover, the timing of the front will significantly influence the final temperature outlook.

Forecasted rainfall amounts with this front vary, with guidance indicating 0.10-0.30 inches along the coast north of Newport and less than 0.10 inches south. Inland, precipitation is projected to be lighter, with expectations of only 0.01-0.05 inches north of Salem and trace amounts south, including over the Cascades.