The two weather patterns in April also had a marked effect on the 

 sea ice conditions. Within a week strong southwesterly winds drove 

 the sea ice rapidly offshore from coastal areas of Cape Race to Cape 

 Freels to an eastern limit of 49° W. with a 25-mile belt extending 

 100 miles further eastward along 48° N. by 11 April. The sea ice 

 east of 50° W. rapidly disintegrated by 16 April due to a combination 

 of heavy wave action from storms, the warmer offshore waters, and 

 the opening up of the pack ice. As the northerly winds returned, 

 heavy pack ice, in abundant supply to the north, was driven south to 

 once more close in on the east coast of Newfoundland. Conditions in 

 Notre Dame Bay were extremely bad with the pack ice under heavy 

 pressure and heavily ridged. A few sealing vessels, which had entered 

 Notre Dame Bay in the earlier part of the month when southwest 

 winds had opened up a lead, got into serious difficulty ; and one large 

 wooden sealer was crushed and sunk. Even the Canadian Depart- 

 ment of Transport icebreakers experienced considerable difficulty 

 navigating into Notre Dame Bay to rescue the sealing vessels caught 

 there. 



The sea ice in the Gulf of St. Lawrence slowly deteriorated as the 

 ice limits gradually retreated and the ice cover diminished so that 

 by the end of April, the Gulf was open water except for the usual 

 lingering ice surrounding Cape Breton Island and ice in the Northeast 

 Arm. The route through the central Gulf and into the St. Lawrence 

 River was considered navigable by 5 April, which is about normal. 

 However, the Canadian Department of Transport icebreakers had been 

 getting ships through the Gulf and to the various ports during the 

 entire winter by the escort system. The St. Lawrence Seaway was 

 reported open on 8 April, the earliest opening date on record due to 

 a mild winter in the Great Lakes and upper St. Lawrence River 

 region. 



MAY 



On 1 May a potential major threat to Track B eiisted in the form 

 of 20 bergs traveling south in the Labrador Current near 46° N., 

 47°30' W. Also to be watched were the group of 15 large bergs tem- 

 porarily aground on the northeast Grand Banks and about 12 small 

 and medium bergs just west of the Current on the eastern Grand 

 Banks between 45° N. and 49° N. See figure 21, ice conditions 

 1 May 1964. On the basis of the preseason northern berg survey of 

 27-28 February and a northern flight on 6 April, it was known that a 

 marked berg gap existed after the first heavy concentration, which 

 had already arrived at tlie Grand Banks. Accordingly it is estimated 

 that there were relatively few icebergs north of the Grand Banks to 

 Belle Isle and many north of Belle Isle. As winds averaged onshore 

 in this area during the last two weeks of April, it was considered that 



16 



