42 U.S. Code § 5132 - Disaster warnings
The President shall insure that all appropriate Federal agencies are prepared to issue warnings of disasters to State and local officials.
The President shall direct appropriate Federal agencies to provide technical assistance to State and local governments to insure that timely and effective disaster warning is provided.
The President is authorized to utilize or to make available to Federal, State, and local agencies the facilities of the civil defense communications system established and maintained pursuant to section 5196(c) of this title or any other Federal communications system for the purpose of providing warning to governmental authorities and the civilian population in areas endangered by disasters.
The President is authorized to enter into agreements with the officers or agents of any private or commercial communications systems who volunteer the use of their systems on a reimbursable or nonreimbursable basis for the purpose of providing warning to governmental authorities and the civilian population endangered by disasters.