Completing the Forecast Characterizing and Communicating Uncertainty for Better Decisions Using Weather and Climate Forecasts (2006) / Chapter Skim
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4 Communicating Forecast Uncertainty
4 Communicating Forecast Uncertainty
Pages 66-97
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From page 66... ...
This chapter addresses the committee's third task: iden- Full disclosure of forecast uncertainty information is tifying sources of misunderstanding in communicating consistent with -- and in fact fundamental to -- NWS's estabforecast uncertainty, including vulnerabilities dependent lished vision for communicating information (Box 4.1)
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From page 67... ...
or no useful uncertainty information; they are simplified and • Provide a "measuring stick" to decision makers to guide deterministic. Members of the public have been conditioned their evaluation of forecasts and forecast uncertainty.
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From page 68... ...
Finding: The public weather forecasts from the IFPS and The provision of single-valued forecasts without uncertainty information (such as error bars on a meteograph) not distributed as the NDFD are one of NWS's primary foreonly exposes a significant limitation of the NDFD/IFPS cast products.
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and the Climate Prediction user community and could be even more widely read and Center's (CPC's) monthly and seasonal forecasts.
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70 COMPLETING THE FORECAST BOX 4.4 Communication of Forecast Information During the Red River Flood of 1997 in Grand Forks, North Dakota Unclear communication of uncertain forecast information can hinder decision making and have significant negative consequences. An example is the 1997 flood in Grand Forks, North Dakota (Figure 4.2)
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. The EC areas can 4.3.1.2 Climate Prediction Center Monthly and be ambiguous because they may also indicate the forecastSeasonal Outlooks ers' belief that each of the categories truly is equally likely.
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The Recommendation 4.3: The CPC should provide full anomaly values for precipitation are based on the difference exceedence probability distributions of the projected between the medians of the "normal" and "final forecast" monthly and seasonal temperature and precipitation distributions. Thus, anomalies indicated on the precipitation values in both graphical and tabular forms.
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. Incorporating this knowledge into NWS As noted in the preceding section, icons have the capaand Enterprise efforts to communicate forecast uncertainty bility to communicate complex information in an easily
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74 COMPLETING THE FORECAST FIGURE 4.7 Example anomaly distribution for a 3-month temperature prediction for southwest Arizona.
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75 COMMUNICATING FORECAST UNCERTAINTY FIGURE 4.8 Example of potentially confusing icons and accompanying text.
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aging the local forecast offices that balances a respect for Dissemination technologies are evolving rapidly, affectlocal innovation and creativity with greater control over the ing how NWS and the other members of the Enterprise activities that affect the public-private partnership, especially approach communicating uncertainty information. Comthose that concern the development and dissemination of new munication devices such as cell phones, personal digital products or services." assistants (PDAs)
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77 COMMUNICATING FORECAST UNCERTAINTY BOX 4.6 Consistency in Communicating Forecast Uncertainty Using Words and Graphics Four forecast products containing uncertainty words or graphics are used in this example: the text forecast (Figure 4.11) for March 5 to 11 (Sunday to Saturday)
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78 COMPLETING THE FORECAST BOX 4.6 Continued FIGURE 4.12 Hourly weather graph for Sunday, March 5 to Tuesday, March 7.
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79 COMMUNICATING FORECAST UNCERTAINTY BOX 4.6 Continued FIGURE 4.13 Hourly weather graph for Friday, March 10 to Saturday, March 11.
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80 COMPLETING THE FORECAST BOX 4.6 Continued FIGURE 4.14 Digital IFPS forecast product for Sunday, March 5 to Wednesday, March 8.
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81 COMMUNICATING FORECAST UNCERTAINTY BOX 4.6 Continued FIGURE 4.15 Probability of snow accumulation. SOURCE: NWS Hydrometeorological Prediction Center.
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82 COMPLETING THE FORECAST BOX 4.6 Continued FIGURE 4.16 Regional synopsis for northern Illinois and northwest Indiana, Sunday, March 5.
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As such, intermediaries, and specifically the media, majority of -- forecast uncertainty information is provided play a critical role in communicating forecast uncertainty to users through "new" media, NWS and the Enterprise will and addressing the challenges presented in doing this effecstill need to serve users who receive their forecasts through tively. To fully understand the implications of this situation, long-standing "traditional" media including television, news it is helpful to understand the business fundamentals of the papers, and radio.
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In addition, SAB may to communicating forecasts represents such a fundamental not be the appropriate venue for dealing with the details and change in the presentation of information that user percep- nuances of forecast uncertainty information and how it is tions and opinions will be needed throughout the product presented and disseminated. development process.
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constant evolution of technology and user needs, as well as the user population itself. 4.5 RESEARCH AND DEVELOPMENT PROGRAM TO IMPROVE COMMUNICATION OF FORECAST UNCERTAINTY 9Information provided to the committee by NOAA describes recent efforts by the NWS Hydrologic Services Division to engage users, commu- Without a stronger knowledge base, NWS and broader nicators, and outside expertise at the initial stage of product development.
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the needs of users for users in key aspects of uncertainty communication. In all, uncertainty information and incorporating these needs into because of the complex, interdisciplinary nature of the topic, communication techniques; (2)
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Second, effective comuncertainty information. With respect to the training compo- munication requires considering and preventing potential nent, academia and government laboratories could partner on user misunderstanding and confusion that can result from developing coursework that addresses forecast uncertainty.
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One way of using maps include developing comprehensive education and training to communicate forecast uncertainty is to portray the spatial efforts and a dedicated, long-term research and development distribution of the likelihood of an event (e.g., tornado) or of program to improve uncertainty communication in hydro- a parameter exceeding a specified threshold (e.g., precipitameteorological forecasts.
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89 COMMUNICATING FORECAST UNCERTAINTY a b 4A-1a fixed im.
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90 COMPLETING THE FORECAST FIGURE 4A.2 Upper bound (90 percent exceedance) and lower bound (10 percent exceedance)
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in hydrometeorological forecasts are two-dimensional. HowOne type of forecast uncertainty graph depicts the temporal ever, three-dimensional representations can also be used (see, evolution of a quantity of interest, with uncertainty repre- e.g., the NRC's Board on Mathematical Sciences and their sented using an ensemble of multiple temporal trajectories, applications workshop "Toward Improved Visualization of box and whisker plots at each time, or probabilities of Uncertain Information")
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, overlaid with NCEP ensemble spread (filled contours)
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Nevertheless, as discussed in Chapter 1, forecast uncertainty. This uncertainty information is not most forecasts received by the public and many users still integrated into the QPF product, however, and thus is likely contain little or no information about uncertainty.
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94 COMPLETING THE FORECAST FIGURE 4A.7 Wind and temperature forecast for days 1-10, including forecast uncertainty. For box-and-whisker plots, the top and bottom of the box represent the 75th and 25th percentile, respectively, while the top and bottom of the lines represent the maximum and minimum.
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95 COMMUNICATING FORECAST UNCERTAINTY FIGURE 4A.9 PDF for the temperature forecast for a specific time and location, summarized into a table of categorical exceedances on right-hand side. SOURCE: UK Meteorological Office.
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4A-11 fixed i. FIGURE 4A.12 Public weather forecast generated by IFPS from NDFD.
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97 COMMUNICATING FORECAST UNCERTAINTY FIGURE 4A.13 Day 2 quantitative precipitation forecast. SOURCE: Operational NWS product, generated by HPC.
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