May 22 - July 31
Beyond the Typical Weather Forecast: Harnessing Probabilistic Graphics for Effective Emergency Management
Gretchen R. Gillenwater, Daphne LaDue, and Alex Marmo
What is already known:
- Emergency Managers (EMs) are constantly aware of any hazards their community could face.
- Although weather affects the majority of incidents EMs handle, less than a third of their training covers weather.
- EMs and other local officials need easily comprehensible weather forecast information to make cost-effective decisions.
- Probabilistic information could lead to a greater understanding of risk.
What this study adds:
- The NWS Monterey Bay began testing two ways of depicting probabilistic forecast information to improve the usefulness of their forecast briefings.
- In a tabletop exercise, EM and other local official participants generally favored seeing probability of exceedance over a box and whisker plot of rainfall amounts, but no one graphic met everyone’s decision needs.
- Participants wanted the NWS to continue to include these graphics in their weather briefings, adding interpretation and more detail in the timing.
Abstract:
Severe weather is challenging to predict but even more so to prepare for. County Emergency Managers (EMs) and other local officials are tasked with the dilemma regularly of being fiscally prudent yet always prepared. Tabletop exercises were conducted in northern California to better understand whether two experimental graphics could better support the difficult decisions being made. First, background interviews were conducted with EMs in two counties before the exercises to better understand local concerns and their decision-making process. All interactions with participants were recorded and transcribed by a professional transcription company. Special attention was given during the analysis regarding the two probabilistic graphics: a box-and-whisker graph and a stacked bar graph. They contained similar information but displayed it in different ways. Because the tabletop exercises had many participants, an anonymous online survey about the two graphics helped ensure everyone could provide their input. Surveys and tabletop discussions were analyzed to better understand how EMs and other local officials use weather forecasts. In particular, how understandable the probabilistic graphics were and whether they would be used prior to a potential flooding event. The results show that both graphs are helpful in the decision-making process. Still, timing and adequate forecasters' input would need to be provided to EMs and other local officials to optimize their usability.