A B S T R A C T This paper presents climatological properties of Northern Hemisphere summer extratropical storm tracks using data extracted from an existing, relative-vorticity-based storm database. This database was constructed using the NCEP-NCAR 'Reanalysis I' data set from 1948 to 2002. Results contrasting summer and winter patterns for several storm parameters indicated general similarity at the largest scales, including the prominent track corridors of the middle latitude ocean regions

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... the mid-continental and east coast genesis zones. Variations between seasons generally consisted of differences in the strength and position of these major features. Several results underscored by this study are: summer storms have longer life-spans than their winter counterparts; the Atlantic track corridor in summer is more tightly confined over northern Europe, whereas in winter it is more diffuse; summertime Atlantic storms are found to be slightly weaker but more numerous than their Pacific counterparts; Pacific storm counts exhibit a large drop from winter to summer that is not observed in the Atlantic; and summer storms appear to be related to the summer NAM, PDO and NAO.