This Technical Procedures Bulletin was written by Morris Bender, Timothy P. Marchok , and Robert E. Tuleya and describes the changes to the GFDL Hurricane Forecast System for 2002. The new 2 nest model has two important resolution changes. First, the outer nest resolution has changed from 1 degree to 1 half degree. Second, the size of the finest resolution was increased from a 5 degree square to an 11 degree square domain. The filtering of the global vortex has been modified in the GFDL initialization, to enable more of the original analysis within the filter region to be retained. These changes resulted in significant decrease in track error in both the Atlantic and East Pacific forecasts. The largest improvements were in the 36-72 hr forecast periods where the track error was reduced about 16%.

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