El Nino tested, no joke. The new closing system is the best on the market. They make white-water rafting bags this way. Piggy-Pack's closing system is like a duck's butt in a pond. No water gets in.
Seams are another issue.
Seam sealer helps a lot. The liner offers protection from any water that seeps thru the double stitched side seam. Piggy Pack and liner offers the best car top waterproof protection on the market. Put the strapping system over the skis and Piggy-Pack then strap the entire bundle down secure. Make sure no sharp objects poke or rub Piggy-Pack the wrong way.