ies. During the summer these centers move directly eastward, 

 near 60° N., into the area west of Hudson Bay. From this position 

 paths vary widely, some centers being forced south-southeastward 

 across the eastern Great Lakes, some proceeding directly eastward 

 into the Labrador-Davis Strait region, and some curving north- 

 eastward across Baffin Island and over Baffin Bay. 



In the latter part of August and in early September, the tra- 

 jectory of these lows across the central part of Canada shifts 

 farther to the south, due to the gradual increase in size of the high 

 pressure cells centered to the northwest of Canada. The northern- 

 most track of low pressure centers moving into the Baffin Bay 

 region is across the Canadian archipelago. These lows originate 

 as waves on the Arctic Front or as developments off the Aleutian 

 Low, which is separated into several small centers during the sum- 

 mer months. The average speed of these lows is 20 to 25 knots, 

 except to the south of the Ellesmere Low, where they tend to 

 intensify and thence move eastward more slowly, eventually stag- 

 nating in Baffin Bay. 



By the time migratory low pressure centers arrive in the Baffin 

 Bay area, the frontal systems connected therewith are usually in 

 the form of well developed occlusions. When these occlusions 

 reach the Greenland coast, they are blocked on the surface by the 

 edge of the cold high pressure cell over the inland ice cap and are 

 either forced aloft or dissipated. 



Frontal weather affects the North American arctic more fre- 

 quently in summer and early fall than in other seasons, but even in 

 summer non-frontal processes predominate. As mentioned above, 

 fronts encountered are generally of the occluded type, although 

 open wave cyclones may also be observed. 



During the fall months, there is an increase in cyclonic activity 

 along the Arctic Front, which extends from southern Greenland, 

 through Iceland, off the northern coast of Norway, over southern 

 Novaya Zemlya and across the Taimyr Peninsula. Winds are pre- 

 vailingly westerly south of the front and prevailingly easterly 

 north of the front. The Arctic Anticyclone continues relatively 

 weak and is centered in its easternmost position along the 80th 

 parallel on the meridian of 140° W. longitude. The transposal of 

 this center to near the Siberian border takes place simultaneously 

 with the freezing over of the East Siberian and Laptev Seas in 

 early winter. 



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