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Global Guide to Tropical Cyclone Forecasting:
CHAPTER 7: WARNING STRATEGIES

7.1 INTRODUCTION

The purpose of strategies, according to management theory (Koontz et al., 1984), is to determine and communicate, through a system of major objectives and policies, a concept of how the main mission of an organisation may be accomplished. Emphasis is placed on the acquisition and deployment of resources (physical, human and information). Warning, response and preparedness strategies thus may be described as:

Contingency planning guidelines that promote objective assessments of the current and changing nature of a hazardous weather threat;

Sequences of actions and announcements that provide the most appropriate and timely response by affected communities.

The strategies thus provide a framework of guidelines to assist decision-making required to counter the threat of an approaching tropical cyclone. For example, as a tropical cyclone threatens a vulnerable section of coast, initially there is a large degree of uncertainty associated with forecast errors at longer time periods. As the cyclone approaches, the uncertainty decreases, but so does the available preparation time. Thus an effective warning and response strategy is to react prudently and alertly at the initial threat, then to marshall all resources to progressively prepare for the developing threat. The type of strategy requires a balance between costs and hardship associated with unnecessary response and the consequences of being caught ill-prepared.. For extreme risk areas with slow response times, for example, it is prudent to evacuate early to avoid catastrophic loss of life, in other regions with rapid response facilities a different strategy could be employed.

The broader objective or mission of an integrated national warning service therefore is:

To promote effective community response, to avoid potential disaster, and thereby to reduce the loss of life, property and environmental damage, and the community disruption to a realistic minimum.

Whilst avoiding potential disaster is a major component of this mission, attention also must be given to reduction of consumption of national resources already scheduled for deployment in national development programs, and consequential triggering of a host of other adverse socio-economic impacts on a nation's prosperity.

In a tropical cyclone context, the strategies may be sub-divided into three, highly interrelated subcomponents:

Forecast Strategy: including the strategy for collection of observations, with enhanced collection in the cyclone vicinity; specialised analysis methods; and the preparation of forecasts using the most appropriate techniques for the situation.

Warning Strategy: including an explicit understanding of the forecast uncertainties; an appreciation of the most vulnerable and susceptible communities in the potential warning area, the "least regret" approach to ensuring no catastrophes occur; and a sharp sense of timeliness to fit with communication capacities and community cycles.

Response Strategy: including public education and awareness programs aimed at ensuring good community responses; developing an infrastructure capable of handling the threat; ensuring a balanced preparation appropriate to the community under threat, to ensure full response without unnecessary over-reaction; taking contingency action, such as establishing emergency operations centres and implementation of ordered evacuations; and deploying available resources to meet the threat and to be available for post-event response.

A major objective of the tropical cyclone strategy should be to provide a strong element of innovative oversight to plan and facilitate the effectiveness of the critical decisions made during the event. This planning will vary considerably according to the meteorological conditions, the facilities and communications available to the community, and its degree of sophistication in responding to threat. It also will be readily understood that the effectiveness of warning strategies needs examination from the perspective not only of national weather service but from the viewpoint of many diverse agencies located in the sequential cycle of disaster mitigation functions. This includes, primarily, the host of potential victims at community level most threatened, and having most to gain from the implementation of effective warning strategies. Thus, experience in one country may or may not be readily translated to another. It may be noted, however, that this chapter incorporates the warning experiences, and lessons learned from a number of recent major tropical cyclones of global significance.

The chapter draws on published and unpublished sources of information, in addition to the author's own practical experience. Particular reference is made to the following readily available publications: Elsberry et al. (1987), WMO (1990) and WMO (1983b). Readers not familiar with modern concepts, principles and practices of data management are invited to refer to two recent publications by ADB (1991, 1992).

Contents Chapter 7.2