Related Clues:

• Watching events closely
• A serious one may be red
• Storm warning
• Emulate Paul Revere
• "Fore!" for one
• Give a heads-up to
• Readiness condition
• Yellow flag
• Fully conscious
• Clear-witted
• Full of NoDoz
• Not dozing
• Fully attentive
• Like good watchmen
• Fully awake