What is NASA's Anvil Rule for Thunderstorms? What is NASA's Anvil Rule for Thunderstorms? What is the Anvil Rule for Thunderstorms? No Space Shuttle launches from downtown Normal this evening What is the Anvil Rule for Thunderstorms? What is NASA's Anvil Rule for Thunderstorms? What is the Anvil Rule for Thunderstorms? No Space Shuttle launches from downtown Normal this evening