Here, we present the results of our 1-km Weather Research and Forecasting (WRF) model prediction, which successfully simulates the full 60-h rapid intensification period and looping southwestward track. We also show verification of our simulated storm structure against various in situ and satellite observations, including those obtained during the Tropical Cyclone Intensity (TCI) field program. To generate realistic synoptic-scale and vortex-scale initial conditions for the deterministic simulation, we run a 24-h dynamical WRF spinup experiment with a 3-h cycling period, in which conventional, radiance, high-resolution AMV, and aircraft reconnaissance mission observations are assimilated into a 3-km background forecast using the WRF Data Assimilation system (WRFDA) in hybrid mode. Ensemble error statistics are derived from an 80-member 9-km WRF ensemble updated using a similar set of observations and the Data Assimilation Research Testbed (DART) EnKF.
Through a series of sensitivity tests, we show that supplying the model accurate initial conditions on the vortex scale, using cycled data assimilation, was essential in capturing the initial southwestward motion and onset of rapid intensification. We also examine the complex synoptic-scale steering environment surrounding the rapidly intensifying Joaquin and compare our model-predicted synoptic scale features against the operational GFS analyzed features. Using this comparison, along with a few sensitivity tests and analysis of the DART ensemble spread, we attempt to better understand 1) the key synoptic-scale features responsible for Joaquin’s unusual track and 2) possible reasons why the operational GFS model struggled with this storm’s track prediction.