Related Clues:

• Blizzard, e.g.
• Blow hard
• Lightning and thunder event
• Radar may track them
• Violent weather
• Subjects of watches and warnings
• Peril at sea
• See 19 Across
• Besiege
• Ominous forecast
• Squall
• Tornado or hurricane
• Attack en masse, as a castle
• Lightning producer
• Dark-clouds bringer