This Fall, Nonstop Extreme Jet Stream Weirdness

Climate Denial Crock of the Week

I just learned a new acronym – “EPO”.


There are a number of atmospheric oscillations that are important drivers of week-to-week weather patterns across North America. The Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO) often get the most attention, but one of the most important pattern oscillations for North America is the Eastern Pacific Oscillation or EPO.

As the name implies, the EPO is a variation in the atmospheric flow pattern across the eastern Pacific, as well as Alaska. When the EPO is in a positive phase, mild Pacific air flows straight into the West Coast of North America. While such a pattern can bring significant rain and snow to the western portions of the country, the air flow warms and dries as it descends down the eastern slope of the Rockies. This results in a warmer than normal pattern across most of the central and eastern…

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