The Weather and Circulation

The most striking feature of the general circulation of April 1954 was the extremely strong poleward temperature gradient which prevailed dong the northern border of the United States, as indicated by the zonal orientation and crowding of isotherms in this area on the monthly mean charts for sea level (Chart I-A) and upper levels from 850 to 300 mb. (Charts XII-XV). The anomalies of temperature at sea level (Chart I-B) and for the layer from 1000 to 700 mb. (fig. 1) show that this month's meridional temperature contrast was much greater than the April normal. Figure 1 highlights the contrast between abnormally warm conditions in the southern three-quarters of the United States and extremely cold temperatures (as much as 12' C. below normal) in practically all of Canada. On many days of the month a quasi-stationary polar front extended across the northern United States, separating cold Canadian air from warm