Predicting and Managing Extreme Events
Extreme events were the focus at the American Geophysical Society Meeting in San Francisco, California on 7 December, 2011. The National Oceanic and Atmospheric Administration Director, Jane Lubchenko, gave the Union agency Lecture, “Predicting and Managing Extreme Events.” As well as focusing on the previously mentioned 12 events, Dr. Lubchenko pointed out that additional extreme events such as the late October winter storm in the NorthEast and the flood and wind damage from Tropical Storm Lee have not yet been fully accounted for.
Dr. Lubchenko also indicated the need for timely, accurate and reliable weather warnings and forecasts. To cover all these phenomena, which have a wide range of spatial and temporal scales, a diverse range of weather observations is needed. These include surface stations, balloons, radar and satellites.
To aid in predicting and managing extreme weather events, they can be divided into three categories, each of which requires a different approach:
- (i) Short-fuse events: Tornadoes, heavy rains, and heat waves require warnings to be issued down to a few minutes ahead, and on the local scale.
- (ii) The progress of extreme events: Tropical storms need to be tracked and forecasted to provide adequate warnings. Since 1995 NOAA’s hurricane forecasting skill has improved substantially. In 1995, the error in the tropical storm track 3 day forecast has reduced from about 270 miles to about 150 miles.
- (iii) Climate forecasts: These are issued by the National Oceanic and Atmospheric administration weeks to months ahead, although the accuracy of long range weather forecasts is little better than chance in some cases, if Environment Canada’s forecasts are an indication.
Managing Extreme Events
To reduce vulnerability to these events, the ability to observe and monitor changes in the atmosphere at sufficient resolution is critical, as noted by Dr. Lubchenko. Theoretical modeling studies can help by assessing the observational network. Do more observations lead to better forecasts? Do more accurate observations lead to improvements? These and other questions can be addressed by carrying out model simulations with additional or better observations added and comparing the resulting simulations.
Future Extreme Weather
In a recent Intergovernmental Panel on Climate Change report, it was recognized that extreme weather may be more frequent in future. The NOAA observations for the USA would tend to support that such a climate change would be part of the trend that has been occurring since 1980 or before. Nonetheless, it is important to recognize that, although extreme weather events are now apparently more likely than a few decades ago, the variability of the atmosphere is so large that we cannot tie a specific event to climate change.
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