the east or southeast already prevails in eastern Europe. Some slight westward 

 progress is made during this period by the cold continental air mass. 



During the period from January 15 to January 19, inclusive, a cold anti- 

 cyclone thrust strongly westward over northern Europe, bringing a marked tem- 

 perature fall over northern areas. Meanwhile the deep Icelandic low was largely 

 obliterated and displaced westward over southern Greenland. In the western 

 Atlantic the lows followed a northerly route into Greenland, while in the central 

 Atlantic they followed an east-southeastward course into the Mediterranean. This 

 is a typical transition from a strong to a weak circulation pattern in the North 

 Atlantic, with complete blocking of the normal northeastward movement of the 

 Atlantic storms. 



From January 20 to 24, inclusive, the continental anticyclone settled 

 slowly southward and soiithwestward. This displacement brings the strong west- 

 ward flow of cold continental polar air southward into central and southern Europe 

 and the Mediterranean. It further displaces the track of the eastward moving lows 

 southward to the southern Mediterranean and northern Africa. Meanwhile the 

 southward shift of the continental anticyclone has terminated the blocking action 

 at higher latitudes. Consequently the fronts and warm air masses which were mov- 

 ing northward in the mid-Atlantic at the beginning of this period are carried 

 rapidly eastward at high latitudes around the north side of the receding anticyclone. 

 This has brought a marked moderation of temperature to Scandinavia and the 

 northern Baltic. This change at high latitudes doubtless represents the first stage 

 of the transition back to a typical strong circulation pattern in the North Atlantic. 

 It will be noted that the Polar Front in the western Atlantic is taking an orientation 

 suitable to the regeneration of a strong Icelandic low. 



The principal additional step needed to complete the transition to a strong 

 circulation pattern is for the European continental anticyclone to move south- 

 westward into the eastern Atlantic and thus to obliterate the cyclonic activity 

 centered there at low latitudes. However, there is little indication of such a change 

 in progress at the end of the period, but rather a tendency towards frontogenesis 

 and increasing cyclonic activity along the southern edge of the European high. 

 Actually strong cyclonic activity in that area developed and persisted for a week, 

 so that it was the first of February before a strong circulation pattern was reestab- 

 lished over the North Atlantic. During this intervening week the Icelandic low was 

 not regenerated, but rather a very strong and nearly stationary low was developed 

 at low latitudes in the western Atlantic. This strong low finally moved up into the 

 Icelandic area at the end of the month. Thus the blocking action and low latitude 

 cyclonic activity of a typical weak circulation pattern actually persisted over the 

 North Atlantic in middle and lower latitudes for a full week beyond the period 

 covered by the daily maps presented here, and beyond the time that normal east- 

 ward motion was resumed north of latitude 60°. 



There follows a brief discussion of some of the features of the individual 

 daily charts during this period which are illustrative of the variety of the daily 

 weather sequence which may be expected over the North Atlantic. 



The map of January 9, 1933, represents a typical strong circulation pattern 

 over the North Atlantic. The open wave character of the zonal westerlies, together 

 with the strong circulation, indicate typical rapid northeastward movement and 

 deepening of the disturbance just beginning to take shape near Cape Hatteras 

 and continued displacement of the occluded southern Greenland center. It will be 

 noted that the Azores high is unusually dominant in the eastern Atlantic, which 

 forces the principal storm centers to follow a route which lies north and west of the 



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