1
Background

When a major East Coast snowstorm was forecast during the winter of 2001, people began preparing—both the public and the decision makers responsible for public services. There was an air of urgency, heightened because just the previous year the region had been hit hard by a storm of unpredicted strength. But this time the storm never materialized for the major metropolitan areas of the mid-Atlantic. The missing storm of 2001 left many people wondering what went wrong with the weather forecast. But did anything go wrong or did forecasters just fail to communicate their information in an effective way—a way that conveyed some real sense of the likelihood of the event and kept people up to date as information changed?

There is uncertainty in all forecasts, and weather and climate forecasts are no exception.1 Traditional weather forecasting uses numerical models and statistical techniques to project likely future scenarios, and these techniques have some level of definable errors. Newer forecasting techniques use more sophisticated ensemble methods that provide a more quantitative measure of uncertainty under certain conditions. Deterministic or categorical forecasts issued by the National Weather Service (NWS), private meteorological firms, and the media can, in some cases, lead the user to misjudge or ignore forecast uncertainty and as a

1  

There are two terms used in this report to describe predictions of future events: forecast and outlook. Forecasts are predictions with more specific information, usually for the relatively short term. Outlooks, on the other hand, are predictions, usually of a more general nature and of a longer ranged projection. One generally thinks of “weather forecasts” and “climate predictions.” As the range of weather forecasts is extended and the seasonal climate projections improve, a blurring of the distinction in these terms is occurring.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 1
A Workshop Summary Communicating Uncertainties in Weather and Climate Information 1 Background When a major East Coast snowstorm was forecast during the winter of 2001, people began preparing—both the public and the decision makers responsible for public services. There was an air of urgency, heightened because just the previous year the region had been hit hard by a storm of unpredicted strength. But this time the storm never materialized for the major metropolitan areas of the mid-Atlantic. The missing storm of 2001 left many people wondering what went wrong with the weather forecast. But did anything go wrong or did forecasters just fail to communicate their information in an effective way—a way that conveyed some real sense of the likelihood of the event and kept people up to date as information changed? There is uncertainty in all forecasts, and weather and climate forecasts are no exception.1 Traditional weather forecasting uses numerical models and statistical techniques to project likely future scenarios, and these techniques have some level of definable errors. Newer forecasting techniques use more sophisticated ensemble methods that provide a more quantitative measure of uncertainty under certain conditions. Deterministic or categorical forecasts issued by the National Weather Service (NWS), private meteorological firms, and the media can, in some cases, lead the user to misjudge or ignore forecast uncertainty and as a 1   There are two terms used in this report to describe predictions of future events: forecast and outlook. Forecasts are predictions with more specific information, usually for the relatively short term. Outlooks, on the other hand, are predictions, usually of a more general nature and of a longer ranged projection. One generally thinks of “weather forecasts” and “climate predictions.” As the range of weather forecasts is extended and the seasonal climate projections improve, a blurring of the distinction in these terms is occurring.

OCR for page 1
A Workshop Summary Communicating Uncertainties in Weather and Climate Information result make preventable errors in the decision process. More sophisticated users of weather and climate information, particularly those in the commercial markets, usually do take uncertainty into consideration in the decision-making process. These users generally receive products and services from the meteorological community that highlight and, in many cases, quantify uncertainty associated with a forecast. However, in the general public market there are occasions when improper statements or lack of explanations of uncertainty can result in inadequate or inappropriate action or missed opportunities. These actions range from the public not taking necessary precautions in a life-threatening severe weather situation to governments and businesses missing opportunities to respond to or mitigate potential long-term impacts of climate variability and change. As sources for weather and climate information have increased, especially given the many sources of information now available on the Web, the issue of confidence in the information has become more important. Communication of accuracy, reliability, and forecaster confidence is made even more complex when issues of climate forecasting are added to the mix. THE CASES SELECTED FOR STUDY Recent history provides a rich record of case studies that can be used to describe the strengths and weaknesses in the communication of weather and climate information to decision makers. This workshop explored five cases representing a range of time scales and issues. They address the forecasting of weather events, seasonal outlooks, and projections of climate change, and include cases in which the forecasts were of high quality and cases in which the forecasts or projections were of uncertain or unknown quality. In each case the impacts were largely dependent on the way the information was communicated. In particular, the workshop focused on the issue of communicating uncertainties. The cases presented are as follows: Red River of the North Flood, Grand Forks, April 1997 (presented by Lee Anderson, Susan Avery, and Roger Pielke, Jr.). This major, record-breaking flood, its forecasts, and the public response illustrate the need for complete information, including a well-defined understanding of uncertainties by the emergency management community. East Coast Winter Storm, March 2001 (presented by Raymond Ban, George Frederick, James Hoke, and Robert Ryan). This case looks at the complicated relationships that link the forecasting community, the media, the public, and decision makers. It also examines the competitive pressures faced by the media when a forecast of a major storm is a headline news story. The case shows how a forecast can be successful from a technical perspective (i.e., provides a relatively sound forecast) but have its usefulness compromised by problems communicat-

OCR for page 1
A Workshop Summary Communicating Uncertainties in Weather and Climate Information ing the uncertainty associated with that forecast, resulting in poor decisions being made by the public, government, and industry leaders. Oklahoma-Kansas Tornado Outbreak, May 3, 1999 (presented by Howard Bluestein, James Lee, and Margaret LeMone). This record-breaking severe weather outbreak illustrates the complexity of communicating weather information in a rapidly evolving, short-time-frame situation and the importance of doing so to save lives. It illustrates the benefit of effective partnerships among the public, private (especially the media), and emergency management communities. El Niño 1997–1998 (presented by Stanley Changnon, Steven Clifford, James Laver, and Robert Weller). The 1997–1998 El Niño was the first major seasonal climate event to occur after the state of the science provided the weather and climate community with sufficient capability to provide a forecast. The case examines methods of presentation of the forecasts, presentation to and reception by certain government and user groups such as the emergency management community in Southern California, and the public’s perception of the event. It illustrates several aspects of the communication of climate information and the confusion that can occur between climate and weather. Climate Change Science: An Analysis of Some Key Questions, June 2001 (presented by Eric Barren, William Randel, and Vaughan Turekian). This discussion summarizes a report produced by the National Research Council at the request of the White House that attempted to provide the administration with answers to questions of climate science related to greenhouse gases and global warming. It illustrates the importance of preparing for public communication when designing a study. Although any number of examples could have been selected for study, these five were chosen because of the breadth of the time scales of the events, the degree to which they have been documented, and the interest and involvement of the workshop participants. To ensure that each case study focused on communication of meteorological information, the presenters were asked to use a standard framework and describe each of the cases in terms of Who? Said what? When? To whom? How? and With what effect?

OCR for page 1
A Workshop Summary Communicating Uncertainties in Weather and Climate Information The presenters provided an initial assessment of these factors that were modified by the ensuing discussion at the workshop. The workshop participants then looked across all the cases for unifying themes, and the final chapter looks at common features of the cases.