July 25, 2017 7:06 pm Storm Science: What Is a Shelf Cloud? They may look ominous, but shelf clouds aren’t the worst parts of a thunderstorm. NBC10 First Alert Weather Meteorologist Krystal Klei explains how they form. US & World Videos 2:03 Members of the Jewish community gathered in honor of Holocaust Remembrance Day 0:23 New Jersey State Trooper died during training, officials say 1:32 More than 100 residents displaced after a fire at an apartment building in West Philly 0:17 Man in critical condition after being shot several times inside a seafood restaurant 0:20 Man in critical condition after being shot inside an apartment building in West Philly