A more thorough explanation:

An anticipatory warrant is a type of search warrant that is issued based on an affidavit that shows there is probable cause that evidence of a specific crime will be found at a particular location in the future. This means that the warrant is not valid at the time it is issued, but will become valid when certain conditions are met.

For example, if the police have reason to believe that a shipment of illegal drugs will be delivered to a specific address at a certain time, they can obtain an anticipatory warrant to search the premises when the drugs arrive. The warrant will only become valid when the drugs are actually delivered to the location specified in the warrant.

Another example is if the police have reason to believe that a suspect will receive child pornography in the mail at a specific address, they can obtain an anticipatory warrant to search the premises when the package arrives. The warrant will only become valid when the package is actually delivered to the location specified in the warrant.

These examples illustrate how an anticipatory warrant can be used to allow law enforcement to search for evidence of a crime that has not yet occurred, but is expected to occur in the future.