Impact of Storm Size on Prediction of Storm Track and Intensity Using the 2016 Operational GFDL Hurricane Model
AUGUST 2017 B E N D E R E T A L . 1491 Impact of Storm Size on Prediction of Storm Track and Intensity Using the 2016 Operational GFDL Hurricane Model MORRIS A. BENDER Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey TIMOTHY P. MARCHOK NOAA/GFDL, Princeton, New Jersey CHARLES R. SAMPSON Naval Research Laboratory, Monterey, California JOHN A. KNAFF NOAA/Center for Satellite Applications and Research, Fort Collins, Colorado MATTHEW J. MORIN Engility Holdings, Inc., Chantilly, Virginia (Manuscript received 20 December 2016, in final form 12 May 2017) ABSTRACT The impact of storm size on the forecast of tropical cyclone storm track and intensity is investigated using the 2016 version of the operational GFDL hurricane model. Evaluation was made for 1529 forecasts in the Atlantic, eastern Pacific, and western North Pacific basins, during the 2014 and 2015 seasons. The track and 2 intensity errors were computed from forecasts in which the 34-kt (where 1 kt 5 0.514 m s 1) wind radii ob- tained from the operational TC vitals that are used to initialize TCs in the GFDL model were replaced with wind radii estimates derived using an equally weighted average of six objective estimates. It was found that modifying the radius of 34-kt winds had a significant positive impact on the intensity forecasts in the 1–2 day lead times. For example, at 48 h, the intensity error was reduced 10%, 5%, and 4% in the Atlantic, eastern Pacific, and western North Pacific, respectively. The largest improvements in intensity forecasts were for those tropical cyclones undergoing rapid intensification, with a maximum error reduction in the 1–2 day forecast lead time of 14% and 17% in the eastern and western North Pacific, respectively.
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