This legislation establishes the Radar Next Program under the Under Secretary of Commerce for Oceans and Atmosphere, in consultation with the National Weather Service Director. The program's primary goal is to develop and implement a comprehensive plan to replace the existing Next Generation Weather Radar (NEXRAD) system, aiming to significantly improve the United States' weather radar network, including its territories. The plan requires developing performance and coverage requirements, collaborating with the broader weather enterprise for solutions, and creating a proof-of-concept phased array radar. It also mandates establishing a weather surveillance radar testbed to evaluate commercial radars and provide technical assistance for gap-filling radars in challenging geographical areas. Crucially, the plan must prioritize initial deployment locations, including sites more than 75 miles from current NEXRAD stations, and incorporate input from various stakeholders like meteorologists and emergency managers. Furthermore, the bill authorizes a Radar-as-a-Service initiative, allowing partnerships with external entities to fill data gaps, supplement radar coverage, and enhance the detection of precipitation and severe weather. This includes considering entities involved in testbeds or the National Mesonet Program, and exploring weather camera systems as supplementary technologies. The Under Secretary is tasked with ensuring the plan's full implementation by September 30, 2040, and providing periodic updates to Congress.