In preparation for the upcoming Atlantic hurricane season, we have identified the top five most common problems with hurricane response plans. Let’s count them down.
The error cone is the area surrounding the track of a storm, or the area of potential threat. Reviewing the past five years’ forecasts, we have determined that 75% of the time, the center of a storm will track within the predetermined error cone. While this tells us how accurate our past forecasts have been, it does not tell us how much uncertainty there may be with a current storm. There is an unknown probability that a storm could move outside the error cone. Over time, with increased data and more accurate predictions, error cones have decreased in size, but this does not directly relate to storm size. Just because you are outside an error cone, does not mean you won’t be impacted by a storm.
To replace the Error Cone prediction, StormGeo has developed its own model called ‘Threatened Regions from Active Cyclones’ or TRAC. The TRAC guide looks at various predictive models and maps the expected track of a storm. TRAC allows for changes in a storm’s size and behavior, resulting in a more accurate prediction of areas at risk.
The Saffir-Simpson Scale of categorizing a storm 1-5 was developed in the late 1960s to estimate the level of damage winds would cause to buildings. In the 1980s, a storm surge scale was incorporated into this model, but this was never the scale’s intended use.
Storm surge is not very dependent on wind levels. A storm’s maximum sustained wind speed depends on the size of the wind field, and the size of the wind field is what generates the Category of the storm. To incorporate wind fields into our predictions, StormGeo has developed a Hurricane Severity Index based on a fifty-point system. Half of the points come from the size of the storm’s wind field, and the other half from the storm’s max sustained wind speeds. The combination of these two factors helps us predict the overall severity of a storm, from its eye to its outer extremities.
Many companies use proximity triggers in their storm response plans. When a storm comes within a certain proximity to a location, this ‘trigger’ will instigate an action or set of actions. As weather changes quickly, a fixed countdown to marker actions is not always going to be accurate. You may find yourself either caught by inaccurate forecasts, or taking unnecessary steps in your plan, which cost your business time and money.
Replacing proximity triggers, StormGeo utilizes a Response Plan Activator. Our hurricane experts, using various models and predictive data, observe any atmospheric disturbance and forecast the track of a storm to evaluate locations under threat. With this information, our clients are notified of potential risks and repeatedly updated with timely information to inform their decision making.
Heavy rainfall can accompany any storm, but what really has an impact on the risk of flooding is whether or not a storm will stall. Intensity of rainfall is not the only concern, but rather, the speed a storm moves. We have seen that predicting exactly where rain might fall is difficult, but we can determine if a storm will stall and cause flooding due to its delayed movement through an area.
Relying on just one forecast to inform your response plan is risky, especially if it is made to the general public about a wide region. This forces you to assume that the forecast you are using is 100% accurate all the time, and that the impacts to your location will be consistent with what the rest of your region sees. Most response plans are triggered by a proximity forecast; mapping out actions to fixed hourly times. Weather changes rapidly, however, so flexibility is key in managing your response plan.
Instead of relying on static goalposts, StormGeo generates a timeline for the evolution of a storm—calculating the likelihood of impact on a specific location. We look at projected track, worst case arrival times, and the probability of impact in an area to create a custom trigger report. This report guides a client through their response plan, calculating when each phase of a plan will need to come into play.
Now knowing these common shortfalls in response planning, check your company’s procedures and protocol. Are all of these factors considered? Planning accurately ensures safety and success through the upcoming hurricane season. For more information about preparing for and responding to hurricanes, check out our Weather Resources.