408 MONTHLY WEATHER REVIEW OCTOBEB 1968 THE WEATHER AND CIRCULATION OF OCTOBER 1958' A Month Characterized by a Pronounced Index Cycle

• Main Author: James F. Andrews
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Canada; Greenland; Major Ridge; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.394.8527; http://docs.lib.noaa.gov/rescue/mwr/086/mwr-086-10-0408.pdf

The average circulation pattern at 700 mb. for October 1958 (fig. 1) bore a rather strong resemblance to the normal for this time of year. Such differences as did exist were related primarily to the intensity of the individual trough-ridge systems making up the planetery wave pattern. In addition, blocking over central Canada, so prevalent during September [l], tended to shear the trough in eastern North America and to displace the highlatitude portion eastward to a position extending from the coast of western Greenland to Labrador. 700-mb. heights over the North Atlantic associated with this trough were as much as 250 feet below normal (Inset, Chart XI). Blocking in central Canada could also be related to the appearance of a high-latitude ridge in that area, while the major ridge over North America extended