The February 13, 1979, windstorm was a natural phenomenon which happened in the West Coast region of

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

and the

Pacific Northwest The Pacific Northwest (PNW; ) is a geographic region in Western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though no official boundary exists, the most common ...

. During the early morning, an intense wave cyclone moved across southern

Vancouver Island Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian province of British Columbia. The island is in length, in width at its widest point, and in total area, while are of land. The island is the largest ...

in British Columbia. South of the low center, a strong atmospheric

pressure gradient In hydrodynamics and hydrostatics, the pressure gradient (typically of air but more generally of any fluid) is a physical quantity that describes in which direction and at what rate the pressure increases the most rapidly around a particular locat ...

was carried across Washington, with associated high winds. With a cold airflow moving toward the northeast interacting with the high terrain of the

Olympic Mountains The Olympic Mountains are a mountain range on the Olympic Peninsula of the Pacific Northwest of the United States. The mountains, part of the Pacific Coast Ranges, are not especially high – Mount Olympus (Washington), Mount Olympus is the high ...

, a lee low developed east of the Olympics. The mesoscale low caused a particularly intense pressure gradient across the Kitsap Peninsula region.

Wind velocity

At 6 mb (mililbars) over 8 miles, the geostrophic wind potential easily exceeded 200 knots (roughly translating to about 100 knots in a geostrophic flow over the Earth's rough surface, or 115 mph). As reported by the crew of the Hood Canal Bridge, average winds reached at least 80 mph out of the south, with gusts in the triple digits. The wind velocities were cross-checked on two different anemometers at the bridge control tower.

Damage

Extensive damage to trees on surrounding private timberland corroborated the extreme intensity of the tempest. The pressure of winds and waves on the Hood Canal Bridge stressed the structure enough to cause catastrophic failure. It is suspected that a severe list in the bridge exposed pontoon access hatches to the waves, which then tore the covers loose allowing water to enter the flotation devices, causing sections to sink. It took nearly three years and over $140 million to rebuild the bridge.

Wind velocity

Damage

See also

References

Further reading