Deterministic Rapid Intensity Forecast Guidance for the Joint Typhoon Warning Center’s Area of Responsibility

Abstract

Abstract Intensity consensus forecasts can provide skillful overall guidance for intensity forecasting at the Joint Typhoon Warning Center as they provide among the lowest mean absolute errors; however, these forecasts are far less useful for periods of rapid intensification (RI) as guidance provided is generally low biased. One way to address this issue is to construct a consensus that also includes deterministic RI forecast guidance in order to increase intensification rates during RI. While this approach increases skill and eliminates some bias, consensus forecasts from this approach generally remain low biased during RI events. Another approach is to construct a consensus forecast using an equally weighted average of deterministic RI forecasts. This yields a forecast that is generally among the top performing RI guidance, but suffers from false alarms and a high bias due to those false alarms. Neither approach described here is a prescription for forecast success, but both have qualities that merit consideration for operational centers tasked with the difficult task of RI prediction. Significance Statement Forecasters at the Joint Typhoon Warning Center are required to make intensity forecasts every watch. Skillful guidance is available to make these forecasts, yielding lower mean absolute errors and biases; however, errors are higher for tropical cyclones either undergoing rapid intensification or with the potential to do so. This effort is an attempt to mitigate higher errors associated with rapid intensification forecasts using existing guidance and consensus techniques. Resultant rapid intensification guidance can be used to reduce operational forecast intensity forecast errors and provide advanced warning to customers for these difficult cases.