Sunday, February 13, 2011

Incredible Winds on Mount Rainier

The closest you can come to a Himalayan experience in the contiguous United States is on Washington's Mount Rainier.  It is the most glaciated peak in the lower 48, reaches 14,410 feet in altitude, and climbing it requires glacier travel and a minimum ascent of at least 9,000 vertical feet.

Mount Rainier and Camp Muir from the south.
Photo: Wikipedia Commons
Mount Rainier also serves up some of the nastiest weather on Earth.  The Northwest Avalanche Center "maintains" a weather observing site at Camp Muir, which is located at 10,100 feet on the southern side of the mountain (see above photo).  Last (Saturday) night, the Camp Muir observing site observed sustained winds reaching 132 mph, with a peak gust of 155 mph.  That's category 4 hurricane force.

The NAM analysis for 0000 UTC 13 Feb, just after the time of peak winds, shows a very strong 500 mb height gradient between a short-wave trough off the Pacific Northwest coast and the long-wave ridge that is parked over the interior western United States.  At 700 mb, very near the altitude of Camp Muir, analyzed free-atmosphere winds near Mount Rainier are 70 knots (77 miles per hour).  Jet level winds are around 125 knots (138 miles per hour).

Presumably flow-mountain interactions led to further acceleration of the flow near Camp Muir.  This is a good example of why the climber's shelter there is built out of stone.

Camp Muir climber's shelter.
Photo: Wikipedia Commons

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