Seiche

We still have 'em, Faladage. I've seen one about 5' one morning fishing with my brother. I heard there was a "wicked good" one about 20' tall sometime in the 50's. They are caused by a tight and fast moving High-meets-Low pressure system boundry that travels parallel to the shore line. The resulting reflecting wave generally dissipates, but that depends on how different the two systems were.