The Pacific Northwest is an area of meteorological extremes, particularly for precipitation.
To illustrate, check out the regional precipitation totals for September 1 to October 17 for this year (see below). Quite amazing.
On the windward (southwest) slopes of the Olympics there was OVER TWENTY inches of rain. In fact, nearly two feet at one location. But a few miles away on the leeward (northeast) side of the barrier near Sequim only 0.83 inches.
Puget Sound received about 4 inches (lower over the north Sound than the south Sound), with precipitation increasing into the Cascades. Large areas of the Columbia Basin, in the rain shadow of the Cascades, had less than a quarter inch.
Bottom line: there was a much as HUNDRED FOLD difference of rainfall between the Columbia Basin and the slopes of the Olympics.
That is impressive.
The craziest contrasts have to be over the northeast side of the Olympics (see a plot of precipitation for the same period below).
One location just south of Port Townsend had only about 0.37 inches and and lighthouse near Sequim only received 0.56 inches. About 30 miles away to the southwest, there was 23.90 inches.
As I have discussed in previous blogs, such precipitation contrasts are mainly forced by terrain, with strong upslope flow on the windward (southwest) side of the Olympics producing bountiful precipitation, while downslope flow on the northeast leeward side results in extreme drying (see schematic)
No wonder folks like retiring around Sequim, from Port Townsend to Port Angeles.
