Challenges of forecasting tropical cyclone intensity change at the Joint Typhoon Warning Center

Optimizing tropical cyclone (TC) intensity forecasts at the Joint Typhoon Warning Center (JTWC) requires methodical application of available analysis and forecasting tools. For example, accurately analyzing TC intensity improves performance of JTWC's most skillful intensity forecast guidance, the Statistical Typhoon Intensity Prediction System (STIPS), because the STIPS scheme incorporates intensity trend data from the TC best track. Unfortunately, TC intensity analysis in JTWC forecast basins is complicated by a paucity of “ground truth,” in-situ observations as well as operational time constraints. Although targeted aircraft and synoptic observations are occasionally available during the analysis process, the JTWC forecaster must typically synthesize data derived from remote-sensing sources alone, including subjective Dvorak fixes, automated satellite intensity estimates, microwave satellite imagery, and scatterometer data. After setting the TC initial intensity, the JTWC forecaster prepares the intensity forecast through careful consideration of large-scale environmental variables, such as upper-level outflow, vertical wind shear, and ocean heat content relative to predicted track, as well as STIPS and dynamical model intensity forecast trends. The forecaster typically affords less consideration to a cyclone's core structure as a predictor for potential intensity change due to a lack of operational guidance. However, the successful application of microwave satellite data to prediction of TC rapid intensification in the Eastern Pacific and Atlantic Ocean basins and the recent development of operational datasets that readily reveal other elements of storm structure, such as core temperature anomalies and lightning trends, suggest that consideration of TC core structure could be incorporated into the JTWC intensity forecast process with positive results.