Severe Hailstorm is a mythos card. It first appeared in the Miskatonic Horror expansion.
Mythos Type: Environment (Weather)
Gate Opens: Devil Reef or Independence Square
Clue Appears At: Esoteric Order of Dagon or The Unnamable
Mythos Ability: Any investigator in a street area at the end of the Mythos Phase must choose 1 item to discard.