Have you been to the Coast this summer? Sure, it’s normal for it to be chilly in the summer along the Pacific Northwest coastline. That’s due to the almost constant northwest wind blowing across the cold ocean water. But this year has been cooler than average with a very persistent onshore flow. For example, Astoria has only seen 4 daytime highs at/above average in an entire month! The first week of August has seen no high temperatures above 65 degrees. The “normal” high in Astoria in July/August is 67/68 degrees.
Obviously that has affected inland areas a bit as well, with those spots exposed to the onshore flow most affected. Seems to me that Kelso/Longview have been a bit cooler relative to Portland than what we normally see. That’s because it’s basically an “open door” to the Pacific down the Columbia River. Farther removed from that influence, Salem’s July high temp was 3 degrees higher than PDX’s. Last year PDX had slightly warmer highs for July.
The image above shows why it’s been cooler at the beaches…a large cold anomaly all along the west North America coastline. Click on the image for a much larger view. Also notice the huge warm anomaly in the rest of the Eastern Pacific. Temps at our latitude way offshore (between Alaska & Hawaii) are between 65-70 degrees!
10pm Weather Update: I’ve never actually been on a mechanical bull, or a real one, but the long-range model ride the last 36 hours has been almost as wild…my neck is even a bit sore. Although that’s more likely from working on that chicken coop digging post holes and lining up big beams. But I digress, here’s the latest:
Big change is that the upper level low is not going to slide down the Coast, but instead move down across Central Washington and into southern Idaho the next two days. That spells a tremendous change for our weather (the forecast at least) west of the Cascades. Gone is the chance for easterly upper level flow and thunderstorms. Almost gone is the chance for showers too. If we get anything it’ll be tomorrow, and even then just a few sprinkles possible here or there. What do we add to the forecast? A much quicker warming trend as the low heads off to the east starts Wednesday too.
A strong upper-level ridge then builds from offshore and flops over into the Pacific Northwest. This causes surface pressure to rise to our north and east, giving us our first offshore (easterly) wind flow event in over a month. A thermal trough develops west of the Cascades and appears to stay there from Friday morning through late Sunday. Some models show the easterly flow reaching the Coast on Saturday. 850mb temps on both the ECMWF and GFS are around +22 to +23 degrees all three days. My chart shows 95-100 degrees. We’ve only seen it that hot one other time this summer, and the likelihood of that happening after mid-August (this weekend) really falls off. So that means this may be the big hot spell for the summer.
Chief Meteorologist Mark Nelsen