Why is Portland so much colder than Seattle?

KING

Portland has had some rough weather to start off 2017. Just this week, they’ve gone from freezing rain Sunday coating everything in ice, a cold rain Monday, and heavy snow beginning Tuesday afternoon. As of Wednesday morning, 6-14 inches of snow had fallen.

The National Weather Service in Portland confirmed it was the most snow they’ve seen since December 2008, over nine years ago. That was about the same time Seattle was getting slammed by Old Man Winter - three weeks of persistent snowstorms and frozen infrastructure.

So what’s happening? Why are they getting snow down there while we are just north of it? A persistent weather pattern has kept most of the Pacific Northwest colder than average the past six weeks or so. In fact, Portland is close to 10° colder than average so far this month.

It has persistently been colder near Portland than Seattle, thanks to the Columbia River Gorge. It’s here where cold air from the interior continues to funnel into the Willamette Valley. You can see recent wind gusts east of the Portland area have consistently been between 30-45 mph the past few days.

Check out how cold it’s been over the interior. Morning temperatures are in the teens and single digits, with somewhat warmer temperatures in the 30’s west of the Cascades. It's nothing that unusual for this time of year.


Below is a snapshot of the real culprit: the Jetstream. The Jetstream acts as a steering mechanism for storm systems, as well as directing cold and warm air. In the image below, the brighter colors indicate faster wind. You can see where the jet is - a stream of stronger wind stretching west to east across the Pacific Ocean, and into northern California.


While California has been seeing flooding rains, areas to the north have been dealing with persistent cold. With cold air in place and a nearby Jetstream, it set the stage for heavy snow in the Willamette Valley.

Bottom line? It’s been colder in Portland thanks to their proximity to the Columbia River Gorge, and the Jetstream has been closer to them giving better opportunities for snowfall. They certainly cashed in Wednesday.

There is good news for those suffering from this cold weather. By this weekend, a warmer and wetter weather pattern begins to take shape. Early next week, a stream of moisture can be seen pumping in heavy rainfall. With the heavy rain threat comes warmer temperatures. It looks like many of us will be back up near 50° by MLK Day.

Copyright 2016 KING


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