Evaluations of the AFWA Weather Research Forecast Model Tropical Cyclone Predictions

Tests of the Air Force Weather Agency (AFWA) Weather and Forecast Model (WRF), which was developed in collaboration with the National Center for Atmospheric Research (NCAR), have produced some encouraging predictions of Atlantic tropical cyclones during the 2005 season. This research examines the performance of the AFWA/WRF for 10 selected cases from six western North Pacific tropical cyclones that had significant intensity changes during the 72-h forecast interval. The model is integrated with 4 km inner-grid resolution nested within a 12 km outer grid to test the capability to predict the intensity. While accurate track predictions are a priority, the WRF must also provide improved intensity guidance over the AFWA MM5 operational (15 km resolution) predictions. If performance similar to the Atlantic can be achieved, skill relative to the statistical-dynamical technique is anticipated. The Auto-vortex routine developed by NCAR is used to re-center the nested grid as often as every time step.

Comparisons will be made with the operational track and intensity guidance at JTWC. Track error mechanisms will be assessed as appropriate. Particular attention will be given to the ability of the WRF model to predict rapid intensification, decay and re-intensification cycles, and rapid decay. These evaluations of WRF model strengths, weaknesses, and biases will then contribute to further WRF development leading to operational implementation at AFWA.