UDC 661.606.1:651.513 “73 ” “1970.12” THE WEATHER AND CIRCULATION OF DECEMBER 1970 Cold and Wet in the North and Far West With Mild, Relatively Dry Conditions Elsewhere

• Main Author: L. P. Stark
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1971
• Subjects: Greenland; North Atlantic; Siberia
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.408.6893; http://docs.lib.noaa.gov/rescue/mwr/099/mwr-099-03-0249.pdf

Principal monthly mean circulation features continued to move eastward this month in middle latitudes while the retrogression of the two previous months in higher latitudes seemed to be over. Some blocking remained in eastern Siberia and weakened appreciably, but the most dominant feature of the Northern Hemisphere this month (figs. 1 and 2) was the blocking regime that became established over the eastern Atlantic. This blocking expanded from an area of weak high pressure near Greenland in November to an impressive ridge with 700-mb heights in December as much as 140 m above normal. The trough off the east coast of North America contributed to this blocking and widespread amplification in the North Atlantic. This deep system averaged 100 m