Related Clues:

• Eclipse, maybe
• Warning, of a sort
• State of high alarm
• See 24-Down
• Awaited sign
• Sign
• Harbinger
• Sudden break in the clouds, say
• Augury
• Black cat, maybe
• Pre-meltdown signal, maybe
• Indication
• Doomsayer's sign
• Foreboding
• Prophetic sign