The Rapid Intensification Prediction Aid (RIPA) was developed for the western North Pacific tropical cyclone (TC) basin. It uses a consensus of two statistical techniques, logistic regression and linear discriminant analysis, to predict thresholds of interest for rapid intensification:
Each technique produces a percentage chance of a given TC meeting or exceeding each threshold, with the consensus providing an unweighted average of the two. If the consensus probability for any threshold exceeds 40%, it will produce a deterministic forecast for the TC to intensify the given threshold (e.g., a forecast intensifying 40 kt linearly over 24 hrs). The deterministic RIPA forecast will be for the highest threshold that exceeds 40%.
RIPA, while designed for the western North Pacific, has been applied successfully to the northern Indian Ocean and the Southern Hemisphere, leading to the exploration of RIPA as a single global method for predicting rapid intensification.
The current real-time version has coefficients re-derived from the combination of the western North Pacific, northern Indian Ocean, and Southern Hemisphere tropical cyclone basins. This version is run on all global basins, and includes the NHC rapid intensification thresholds (the 24 hr and 36 hr thresholds were already included) of:
Further details on RIPA are available from: Knaff, J. A., C. R. Sampson, and K. D. Musgrave, 2018: An operational rapid intensification prediction aid for the western North Pacific. Wea. Forecasting, 33, 799-811. doi: https://doi.org/10.1175/WAF-D-18-0012.1
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