The National Weather Service, in cooperation with the University of Delaware, is planning to nationalize a new format for heat/health advisories and warnings to be issued by their Weather Forecasting Offices. These new systems are different from the existing ones in several important ways. First, the systems are based on actual weather/health relationships in each urban area. Thus, thresholds to call warnings are related to meteorological conditions that, in the past, have led to increases in mortality. Second, the systems are different from one locale to the next. Thus, conditions necessary for advisories and warnings to be called vary considerably among urban areas. Third, the basis of these systems is synoptic climatological in nature, and oppressive conditions are identified by determining air mass types that have historically been associated with heat-related deaths.

These types of systems are presently in operation in 11 U.S. cities and 3 international urban areas, and have been working successfully. It is planned that every major city within the country will have a system of this type within the next three years.