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Wind, Waves and Tides

Posted: December 19th, 2016
Despite high pressure, Saturday morning’s 12.1′ MLLW high tide was lower than predicted, but 5 knot northerlies still created a little drama at Alki Beach. Photo by Jason Bell via West Seattle Blog.

Despite high pressure, Saturday morning’s 12.1′ MLLW high tide was lower than predicted, but 5 knot northerlies still created a little drama at Alki Beach. Photo by Jason Bell via West Seattle Blog.

 

Last Monday’s weather forecast was not that exciting: a few snowflakes; otherwise cold and dry. More noteworthy was the fact that another round of King Tides was imminent. Predicted water levels Wednesday through Sunday were over 12-and-half feet (relative to mean lower-low water).
 

The good news was that the same high pressure that would provide the cold and dry weather would also suppress water levels via the inverted barometer effect. However, cold high pressure often comes with substantial northerly winds, which indeed arrived and drove a few waves toward north facing beaches such as Alki (pictured above).
 

Looking ahead, the edge of a wind storm will once again cause waves to crash ashore on Tuesday morning, this time to west-facing Puget Sound beaches. Tomorrow’s otherwise unimpressive predicted tide of 12.18′ MLLW at 10:09 am roughly coincides with high wind forecasts. Fortunately, the storm is expected to track sufficiently far enough north that low pressure will not worsen water levels. That said, if the National Weather Service’s High Wind Watch and forecast verify, there will be even more dramatic shots from places like West Seattle tomorrow.

 

JRH