Evaluation of COAMPS-TC Forecasts For Hurricane Patricia (2015) Using a New Dynamic Initialization Scheme with ONR TCI Datasets

From 21 to 23 October 2015, Eastern Pacific Hurricane Patricia underwent a period of extreme rapid intensification that numerical weather prediction (NWP) models failed to predict, including the Navy operational model for hurricane prediction, the Coupled Ocean/Atmosphere Mesoscale Prediction System for Tropical Cyclones (COAMPS-TC). Using spatial and temporal resolution in-situ sounding data from the Office of Naval Research (ONR) Tropical Cyclone Intensity (TCI) campaign in 2015, it was demonstrated that the real-time initialization of COAMPS-TC using a bogus vortex produces a tangential wind outer field that was too broad in comparison to observations, a missing outflow jet, and a radius of maximum winds that was too large. These initial condition errors contributed to subsequent intensity errors.

In order to further understand the role of initial condition errors in intensity forecast errors of Patricia, a numerical modeling study is conducted with COAMPS-TC. A control experiment using the current static bogus vortex initialization is compared to a new dynamic initialization scheme using combinations of different TCI experiment special datasets: (i) a special set of 15-minute temporal resolution Atmospheric Motion Vectors (AMVs), (ii) High Density Digital Sounding System (HDSS) dropwindsondes, and (iii) Hurricane Imaging Radiometer (HIRAD) surface wind speed data. It is demonstrated that incorporation of these special datasets into the initial condition of Hurricane Patricia in the dynamic initialization framework leads to improved initial analyses and subsequently improved intensity forecasts during the period of extreme rapid intensification.