Figure 61. Four l(nv [)ressiii(' systems typical of conditions Avliicli existed (liu-ing tlie winter of 

 l!tTl~1072. a. 3 I)eceml)er 1971. 1). 6 January 1!)72. c. 2 February l!»7-2. d. :'. March 1972. 

 Contour interval is 4 decibars. 



67 



