1-15 March, and 16-31 March charts indicates a remarkable similarity. 

 However, when it is considered that the 15-28 February and the 1-15 

 March charts are more representative of abnormally cold years and 

 that the 16-31 March includes the warm years, it is easy to reach the 

 above conclusion. 



2. A warming trend is barely detectable in the 1-15 April chart. 

 Overall on the Grand Banks and vicinity, the sea surface temperatures 

 have risen about 1° F. However there is no noticeable warming on 

 the eastern slope of the Grand Banks north of 46° N., or on the north- 

 ern Grand Banks north of 47° N., between 45° W., and the coast. It 

 should be pointed out that these are key locations for bergs likely to 

 reach the major shipping lanes at the Tail of the Banks. Ice Patrol 

 records show that while most bergs have drifted south of 48° N. during 

 April, May has been the heaviest berg month in the major shipping 

 lanes. 



3. A comparison of the 1-15 April and 16-30 April charts shows a 

 very slight warming trend in most areas, except that the critical area 

 at the Tail of the Banks (41° N., 43° N., 49° W., 52° W.) has become 

 colder. The cooling at the Tail can be explained by the greater 

 strength of the Labrador Current just prior to and during this period 

 and the fact that the average temperature of the Labroador Current at 

 this location is probably coldest at this time of the year. While the 

 32° F. isopleth has retreated 60 miles to the north along the east slope 

 of the Grand Banks, it is approximately in the same location for 16-30 

 April as 1-15 April on the remainder of the Grand Banks. The 36° 

 F., 40° F. and 44° F. isopleths for the 16-30 April chart are almost 

 identically located as their 1-15 April counterparts. 



4. The warming trend becomes more noticeable during 1-15 May. 

 The 32° F. isopleth has retreated an average of 40 miles northward and 

 slightly westward from the 16-30 April normal. The 36° F. isopleth 

 has retreated about 40 miles northward and 10 miles westward on the 

 Grand Banks. All other isopleths have generally retreated somewhat 

 northward and westward. Generally temperatures are 1° F.-2° F. 

 warmer than for the previous period. 



5. The 16-31 May normal isotherm chart indicates an acceleration of 

 the warming trend. The 32° F. isopleth has disappeared and there is 

 generally about a 2° F. rise in surface temperature as compared to the 

 1-15 May chart. 



6. The 1-15 June normal shows a 2°-3° F. rise in sea temperatures 

 over the previous period, reflecting a sharp warming trend. The 36° 

 F. isopleth has disappeared. The temperature at the Tail of the Banks 

 has risen from 40° to 44° F. 



7. The 16-30 June chart, should not be considered a normal chart 

 as it probably represents colder than normal temperatures. Neverthe- 

 less, the strong warming trend is obvious. The 40° F. isopleth has 



37 



