Severe weather threat increases around Portland this weekend

PORTLAND, Ore. ( KOIN ) — The threat of severe weather increases along the Willamette Valley, including the Portland, Vancouver metro area this weekend.

A ‘ marginal risk ‘ for severe weather is possible for much of western Oregon starting Saturday afternoon and lasting through the evening hours. A ‘marginal risk’ means there’s a one out of five chance of seeing damaging winds, large hail, and even the rare threat of tornadoes. Although this threat is relatively low, it is greater than what is typical for the greater Portland, Vancouver metro area.

Temperatures Saturday will be warm enough to help lift warm, moist air up into the atmosphere. A weather disturbance offshore Saturday will also give way to more atmospheric instability. It’s these processes that leads to convective storm development . The potential energy in the atmosphere over the Portland, Vancouver metro area is higher than normally forecasted with a chance for rain. Rain accumulation is still uncertain at this time. However, many weather models are closing in on nearly 0.1″ to 0.25″ of rain by the end of the weekend.

Some localized flooding is possible with Saturday night and Sunday morning’s rain. The greatest flood prone locations are around burn scar areas. Recently burned areas will have a difficult time absorbing rainwater, causing rapid runoff to occur in some locations.

The greatest chance to see severe thunderstorms around Portland will happen just before sunset. That’s when the potential energy is at its highest. Rain showers are possible before that, but the heaviest of the rain will happen around 8:00 p.m. Saturday. Showers will likely linger into Sunday with cooler than average temperatures taking the Rose City into next week.

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