ency to merge with the strong Icelandic circulation. The rapid advance of a second 

 strong disturbance into a well developed Icelandic center during periods of strong 

 circulation in the Noith Atlantic frequently leads to an exceptionally intense 

 development of the Icelandic low. 



On the morning of January 13 conditions are little changed. The blocking 

 effect of the continental anticyclone remains unchanged in northern Europe, but 

 the strong circulation and rapid eastward movement of the fronts and low centers 

 at high latitudes over the Atlaaitic continues unabated. In spite of the fact that the 

 disturbance over southern Greenland now moving into the Icelandic low is an old 

 disturbance and long since occluded, the large negative pressure tendencies in the 

 entire area from southeastern Greenland eastward to Iceland and southward to 

 latitude 50° N indicate that a strong deepening of the center is already in progress. 

 It is to be noted also that this deepening occluded system is carrying northeastward 

 a current of quite warm air. so that a large temperature contrast exists in the low 

 pressure trough between Greenland and Iceland. 



The map of January 14 shows that quite a severe storm developed as a 

 result of the marked deepening of the Icelandic center, but the storm center con- 

 tinues to move northeastward with unabated speed. Strong southerly gales are 

 occurring along the outer coast from Scotland northeastward. The strength of 

 these winds, or the exceptionally steep pressure gradient which prevails in this 

 region, is caused in part by the persistence of the continental anticyclone over 

 northern Europe. This is generally true in the North Atlantic that the most severe 

 gales do not necessarily occur with the strongest development of the Icelandic low 

 or similar storms, but rather when strong cyclogenesis occurs in close proximity to 

 an abnormally strong and persistent anticyclone. Both stronger winds and deeper 

 lows than appear in the storm under discussion are observed in the North Atlantic, 

 but they do not necessarily appear together. Only twelve days previous to this 

 date, on January 2, a disturbance which moved northeastward from Newfoundland 

 to Iceland as it occluded and deepened, lesulted in an intensification of the Icelandic 

 low to below 930 mb. for two days, but no wind velocity in excess of ten Beaufort 

 was reported. However, winds of eight to ten Beaufort were reported from a much 

 greater area than in this case. The strongest winds reported from Iceland usually 

 blow with an easterly component when the storm center is south of the island. 



One additional feature to be noted on this map is another disturbance of the 

 Alberta type which is moving very rapidly eastward in central Canada, a continua- 

 tion of the strong pattern of the general circulation. 



On January 15 some significant changes in the general circulation pattern 

 begin to appear on the weather map. The strong outflow of cold air behind the 

 recently intensified Icelandic low has swept the Polar Front much further south in 

 the eastern Atlantic, so that it has taken an east-west orientation at lower latitudes, 

 and has terminated the domination of the Azores high in the eastern Atlantic. 

 This is the first step necessary for the establishment of a weak circulation pattern 

 in the Atlantic. Disturbances which now develop on the Polar Front should be 

 carried eastward and even southeastward into the Mediterranean. The field of 

 pressure tendencies in southwestern Europe and the Bay of Biscay indicate a strong 

 tendency to a further southeastward displacement of the Polar Front in that region. 

 Meanwhile the continental anticyclone in the north continues to block the eastward 

 advance of the frontal system over the continent at higher latitudes, while the 

 extremely rapid eastward advance of the latest Alberta low has continued across 

 northern North America. It appears also that over North America the eastern 

 extension of the Pacific Polar Front is being displaced southward from Canada into 



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