14B.4 Predictability Associated with Interactions between Recurving West Pacific Tropical Cyclones and the Extratropical Large-Scale Flow

Thursday, 4 June 2009: 11:15 AM
Grand Ballroom West (DoubleTree Hotel & EMC - Downtown, Omaha)
Heather M. Archambault, University at Albany/SUNY, Albany, NY; and D. Keyser and L. F. Bosart

Interactions between recurving western North Pacific tropical cyclones (TCs) and the extratropical large-scale flow may result in periods of reduced predictability over the Pacific Ocean and North America. The roles of initial-analysis and model-physics errors in limiting predictability during such episodes are investigated by conducting multiscale case studies for episodes of recurving western North Pacific TCs for the period 2004–2008. Episodes are categorized as having relatively high or relatively low predictability based upon daily GFS anomaly correlation coefficients computed for the North Pacific–North American domain. Rossby wave train propagation and associated jet streak evolution for high and low predictability episodes are compared using dynamic tropopause (DT) plots created from NCEP GFS and Global Ensemble Forecast System gridded analysis and forecast data. Preliminary results suggest that TC/large-scale flow interactions tend to be associated with lower predictability over the North Pacific–North American domain when cyclonic, rather than anticyclonic, wave breaking on the DT is induced.
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