The answer lies with wavy jet stream.
by Mike Godsey, mike AT iwindsurf.com
At the Hatchery this 2016 summer season 2 topics beyond the endless chatter about sail sizes are common. Most common are: 1. Why aren’t we getting the consistent 4.2 sail size winds typical of summer. It seems the average winds are either weaker than normal or stronger than normal. 1. What happened to the normal progression of warm windy days occasionally punctuated by heat waves then cloudy blasts of cool air. This has led to some calling this the Feast or Famine summer wind wise.
One thing is clear. There are a lot more upper troughs & lows at ≈ 18,000 ft. sliding past the Gorge this summer. And when they pass just a bit to the north their strong WNW to WSW winds aloft create a wind feast. But when the upper troughs & lows come too close to us, like Sunday Aug. 7, they create anything from crazy up and down winds to weak winds to “you had to be there at the right moment winds”.