Weather and of the Pacific The and climate of the Pacific Northwest Northwest and southern B.C. is dominated by terrain and the presence of the Pacific Ocean

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Washington has the sharpest weather contrasts in the US, with rainforests and deserts in close proximity Hoh Forest (150-170 inches/year)

Squim (10-20 inches/year) Interesting Local Weather Interesting Local Weather

• Wind : • Wind Storms: – Flows along gaps in mountains – Flows along gaps in mountains – Flows in Puget Sound – Flows in Puget Sound • Puget Sound Convergence Zone • Puget Sound Convergence Zone • Pineapple Express • Pineapple Express • Marine Push • Marine Push • Puget Sound Diurnal Sea Breeze • Puget Sound Diurnal Sea Breeze

Columbia Gorge

• In , the air in eastern Washington is very cold (dense) and the SLP is often high compared to that offshore – Result: strong easterlies in gorge • Cold air drainage down the gorge undercuts warm moist air coming in from the west. Result: ice storms – Result: ice storms in gorge Cold, dense air and upper Willamette Valley High SLP Warm, moist air Low SLP Portland Columbia Gorge Enumclaw, Washington “Place of evil spirits” • In , the air in eastern Washington is very hot (light) and the SLP is often low compared to that offshore Low SLP – Result: strong westerlies in Low gorge (sort of a large scale sea breeze) High High SLP – Wind is against the river current (special for windsurfer)

Large Pressure Gradients along the gaps in the Cascades amplify mountain waves and cause strong flow down the gaps

Enumclaw, Washington December 24, 1983

A Huge Pressure Gradient developed across the Cascades (17mb SLP drop), which caused the air to accelerate through gaps in the Cascades into the Puget Sound Lowlands Winds (in mph) Enumclaw and nearby foothills locations can :=(%3+(".7 experience severe windstorms…while calm winds >'.$3+"(*3%0(- occur a dozen miles away 7-.-(0##? 033"6'0+-$%>'+, 3+(".7%#"> F(-33=(- Winds over 118 mph 3?3+-*39%60##-$ December 24, 1983 *'$#0/+=$- 6?6#".-3

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Whether and where a wind happens depends on the strength and critically on the nuances of the track of the midlatitude

Easterly (or Westerly) Wind Surges in the Strait of Juan de Fuca Low Pressure

Low SLP

High SLP

High Pressure 8'.$%60.%(-06,%OKPQK Large Pressure Gradients along the gaps in the Mountains *F, cause strong flows down the gaps Fraser River Gap Windstorms Fraser River Gap Winds

Cold Air High SLP Gusts above 90 PGF mph Gap

Cold air in interior BC is pushed through the Fraser River gap by the strong PGF along the gap axis December 28, 1990

The Squamish Wind: can reach 70-100 mph

Picture courtesy of Skagit Valley News