the cover is a Classic Accessories PolyPRO. Its not really 100% water proof but for the most part it does shed a lot of the water load.
hear on the East side of USA we get these storms called "nor'easters"
moisture comes across the bottom of US, hits the ocean and turns north up the coast, as it goes north it gets stronger. Most times this is heavy snow great for making snowman.
Even though I am 100 miles inland, most of the land around us is 300 feet above sea level, but I live at 1000'. Going home its like changing climates. many times we see rain than the last mile or so its snowing.
Plus to the west of me is another large valley (Lancaster Valley) so wind wipes across valley than accelerates as it climbs up the large hill I live on (we call it a mountain on East coast :) )