The phrase "worst snowstorms" refers to the most severe or extreme snowstorms that have occurred. These snowstorms are characterized by heavy snowfall, strong winds, and potentially dangerous conditions. Full definition
Crews are out in force, deficit be damned, but Hizzoner also got lucky; the sixth worst snowstorm in modern city history fell amid Christmas vacation. (nystateofpolitics.com)
We ended up having a green Christmas too, but we are supposed to get a pretty bad snowstorm this afternoon (better late than never, I guess? (have-clothes-will-travel.com)
I drove my 2007 GL450 drove all the way from Seattle to Michigan with my wife through some very bad snowstorms. (cars.com)