There is a change coming to the Pacific Northwest….
After a good, long spell of unusually warm and mostly dry conditions, the weather guessers are calling for some rain, maybe quite a lot of rain. Our area has been under the influence of what the professionals call a persistent upper level ridge of high pressure which has been directing marine air around us by pushing the Jet Stream to the north. That pattern is breaking down and will cause the upper level flow to become more “zonal” which is a technical term for “aimed right at us.
The forecast models for this particular weather change have several moving parts. There is a warm ocean. There are remnants of typhoon Phanfone embedded in the approaching frontal system and the jet stream is focusing its energy into a narrow band centered on the Washington/Oregon Coast. This creates what meteorologists call an “atmospheric river” producing heavy rains and serious winds. Particularly warm ones with most of their moisture originating in the tropics are sometimes also referred to as “the Pineapple Express”. The 1962 Columbus Day Storm is an extreme example of what these systems can be like.
When these systems arrive in early to mid-autumn, they can produce interesting birding along the coast and (sometimes) even interior lakes and large rivers. This can be a good time to set up the spotting scope at a good sea-watching location and watch for near-shore occurrences of tubenoses and other pelagic species.
The models that forecasters use to predict these early transitional systems are not in total agreement about the coming weather shift, and they are most definitely not predicting anything on the scale of a Columbus Day Storm, but keeping a weather-eye on these early fall systems can benefit the intrepid birder.
You can follow progress of model interpretations among the professionals at:
And other interesting climate info at Cliff Mass Weather Blog