ABSTRACT

The reliability of weather forecasting is of concern to everybody. In this paper a presentation of the needs of the offshore industry with respect to knowing the uncertainties in weather forecasting will be given. In this context the industry must be aware of the inherent uncertainties in weather forecasting and take this into account in planning of offshore operations. Furthermore, the meteorologists must honestly admit the limitations of their weather forecasts. It is suggested that the uncertainties are quantified as a function of time elapsed after the forecast has been made. A discussion regarding the suggested format for presentation of the industry requirements and the resulting forecasts will be given. In this context emphasis is put on the operational threshold when operations must be put on standby and the survival threshold when continued operations may cause severe damage. Some suggestions regarding future analysis and priorities are presented. A list of relevant references is enclosed.

INTRODUCTION

There are at present large uncertainties in weather forecasts, however, regardless of whether more data can be collected and whether more accurate computer models can be constructed and more CPU time can be made available, there will always remain some uncertainties associated with the forecast of the weather. It is obvious that these uncertainties increase with the time after the weather forecast has been made. A forecast extending beyond one week is considered to have some degree of reliability only if a stable high pressure situation exists. The offshore industry's need for reliable weather forecasts increases, however, as the industry carries out increasingly more complex offshore operations requiring increasingly longer periods of relatively low waves and low wind speed. There is also a requirement to prediction of the ocean currents. A discussion regarding prediction of currents is, however, outside the scope of this paper.

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