Tropical cyclone wind radii estimation utilizing an empirical inland wind decay model

Methodology:

The National Hurricane Center (NHC) is required to issue forecasts of the radii of 34, 50, and 64 kt winds for tropical cyclones every 6 hours as part of their forecast/advisory package. The goal of this NOAA Joint Hurricane Testbed project was to utilize the Kaplan and DeMaria decay model (Kaplan and DeMaria 1995, 2001) to provide guidance that could be used to help make such wind radii and maximum wind forecasts for systems that make landfall during the forecast period. The Kaplan and DeMaria decay model is currently used in the SHIPS model (DeMaria et. al 2005) to predict the post-landfall decrease in maximum sustained wind speed near the storm center and by the Federal Emergency Management Agency (FEMA) to estimate the maximum potential wind speeds that might be experienced at inland locations. The decay model can also be utilized to provide a 2-dimensional post-landfall wind field (Kaplan and DeMaria 1995) and this is the application that is being employed to obtain the wind radii estimates in this study.

Probabilistic Rapid Intensification (RI) Forecasts in the Atlantic and E. Pacific Basins

Methodology:

The OAR has identified obtaining guidance on the timing and magnitude of episodes of rapid intensification (RI) as one of the highest operational tropical cyclone forecasting priorities. In an effort to provide a tool to aid in the forecasting of rapid intensification, an updated index for estimating the probability of rapid intensification (Kaplan and DeMaria 2003) has been developed as part of the NOAA Joint Hurricane Testbed. The rapid intensification index employs 5 large-scale and 2 satellite-derived inner-core predictors from the SHIPS model (DeMaria et al., 2005) to estimate the probability of rapid intensification for the 24-h period commencing at t=0. The 2006 version of the rapid intensification index differed from that used in previous seasons in a few areas. First, the threshold for rapid intensification was lowered slightly from a maximum sustained wind increase threshold of = 30 kt in 24 h to a threshold of = 25 kt in 24 h. Also, the methodology for deriving the index was modified so that that the contributions from each of the rapid intensification predictors represented a scaled value between 0 and 1 rather than simply a 0 or 1 as had been employed in the previous version of the index. Finally, a second version of the RI index was derived using predictor values that were weighted utilizing linear discriminant analysis (Wilks 1995). A more complete description of the methodology used to derive the 2006 rapid intensification index can be found in Kaplan and DeMaria (2006).

Objective:

Atlantic Oceanographic and Meteorological Research - Hurricane Research Division - 2007 Science Projects

Objective:

The purpose of this project is to examine the evolution of the wind field of Hurricane Rita (2005) as it evolved from a primarily symmetric storm to a storm with concentric eyewalls and finally to a storm becoming highly asymmetric as it made landfall in the northwest Gulf of Mexico.