Some marine surges are easy to track because the fog actually curves into the Lower Columbia River and you can basically watch the surge take place. At other times the upper ridge is bringing crushing heat and the fog can’t really fill into the Lower Columbia. Happily, though, there are other variables that can help us to discern that the marine surge is kicking in. Notice the below imagery.
So, on Wednesday, September 11th the Pacific Northwest was experiencing record breaking heat. In fact, the upper ridge brought crushing heat to Portland with a high of 95F. In fact, one indicator that the heat would bake Portland was the massive -0.11″ easterly pressure gradient from Portland to the Dalles. This helped to produce moderate easterlies for Rooster Rock and Stevenson through the morning. Meanwhile, the marine surge progressed at the coast (as indicated by the time series above) and Astoria topped out at a mere 64F. This massive thermal gradient from Portland to Astoria helped drive a solid pressure gradient from Astoria to Portland (reaching 0.11”, shown above) and resulted in the WNW blast at Jones Beach with winds reaching solid mid 20’s and some brief upper 20’s!
-Benjamin Miller, WeatherFlow Meteorologist