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Impacts and Evaluation
NSSL's mission is to carry out research to help improve the forecasts and warnings of the National Weather Service. We recognize the importance of understanding how weather impacts the public and how forecasts can provide benefits. Scientists from the MAG work on a range of topics including identifying the effects of the weather, measuring the impacts of forecasts, and providing information that can help inform policy makers in their decision-making processes.
DEATHS AND DAMAGE FROM SEVERE WEATHER
TORNADOES
Historically, NSSL has led work to understand
the meteorology of tornadoes. As part of that, the MAG has looked at the
historical trends in tornado impacts on life and property in the US.
- Deaths
The history of deaths in tornadoes in the US since 1875 has been summarized in a formal manuscript. Death rates dropped from 1925 into the mid-1990s. The death rate appears to have leveled off since then. The rates of death for residents of permanent and mobile homes have been a particular source of interest. - Damage
Property damage from individual tornadoes has increased over the years. In a formal paper, it was shown that this increase has been the result of inflation and the increase in wealth of the US over time. The thirty most damaging US tornadoes since 1890, adjusted for inflation and for wealth, can be seen in this table. From that, we can see that a tornado causing damage on the order of the 3 May 1999 Oklahoma City tornado can be expected about once per decade.
LIGHTNING
MAG staff were instrumental
in developing national
lightning safety guidelines and educational materials. Analysis
of lightning statistics was
carried out to look at the impact of such efforts. From 1996-2004, the
mean annual US lightning death toll reported in Storm
Data was 45.1, down from 73 in 1982-1990.
TORNADO WARNINGS
While other parts of NSSL work to improve the detection of tornadoes, reduce false alarms in warnings, and increase lead time, MAG members and collaborators have concentrated on looking at the warning system. Using econometric models, collaborators have estimated that the WSR-88D radar network reduces deaths in tornadoes by about 45%. Research has offered an explanation of the slow change in false alarms compared to the large change in probability of detection, based on signal detection theory. Current research is looking into the question of how long people in different counties in the US spend under tornado warnings each year and, from an economic approach, the opportunity cost of those warnings.
FORECAST EVALUATION
The MAG includes people who are world-recognized experts in the evaluation of forecasts. New techniques for evaluating numerical models have been developed. The international team evaluating experimental forecasts from the 2000 Sydney Olympics included a MAG member, who now serves on the World Meteorological Organization's Joint Working Group on Verification.
PUBLIC POLICY
MAG staff have been involved in providing information
on a national and international level to policy-making bodies. Presentations
to Congressional staff, the United Nations/World Meteorological Organization
International Decade for Natural Disaster Reduction, Intergovernmental
Panel on Climate Change workshops are included in our activities. The Third
Assessment Report on the
Scientific Basis of Climate Change 
of
the Intergovernmental Panel on Climate Change includes a MAG member as
an author. The US
Climate Change Science Program Synthesis and Assessment Product on Climate
Extremes
includes
a MAG scientist as a lead author.
