Real-Time and Postseason Tropical Cyclone Intensity Estimate Differences Weather and Forecasting

Global tropical cyclone warning centers construct representations of the vortex with estimates of intensity, central pressure, and position. This work analyzes differences between the real-time and postseason intensity estimates analyses. Using tropical cyclone data for 2004-23 seasons from the North Atlantic basin; eastern, central, and western North Pacific basins; north Indian Ocean Basin; and Southern Hemisphere basins, this work shows consistency between most estimates. But further examination illustrates that only 29%-38% of cases have consistent intensity estimates during extreme intensity change (i.e., rapid intensification and weakening). For the inconsistent cases, this work evaluates how the real-time estimates differ from observations and explores the impacts on future intensity forecast skill. During rapid intensification, forecasters can increase 12- and 24-h intensity forecast skill with improved initial intensities roughly 70% of the time with over a 10% skill improvement relative to a baseline forecast. This work shows similar results for 12-h rapid weakening intensity forecasts and also indicates that adjusting the initial intensity during rapid weakening provides trivial skill improvement relative to a baseline forecast at 24 h. The results suggest that improving the current intensity estimate through more accurate, more frequent, and timely low-latency detection will yield better tropical cyclone intensity forecasts. Significance Statement Tropical cyclone warning centers use the current maximum sustained near-surface wind speed (i.e., intensity) to convey and predict impacts and hazards. This work quantifies differences in the real-time, operational intensity estimates from the poststorm assessment of position, wind field, and intensity. Where the values differ, this work compares all analyses to analyses during extreme intensity changes (i.e., rapid intensification and weakening). This evaluation highlights that during rapid events, forecasters deviate from the available current intensity estimate information, potentially indicating a detection problem, large uncertainty in intensity estimates, or influence of other outside information like storm environment. Exploring these differences further, forecasters could improve 12- and 24-h intensity forecasts with better current intensity estimates.