THE WEATHER AND CIRCULATION OF OCTOBER 1968 UDC 551.506.1:551.513551.524.35 Progression of Large-Amplitude Features at Midlatitudes With Rapidly Varying Temperatures

• Main Author: A. James Wagner
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic; Arctic Ocean; Greenland; Gulf of Alaska; Lorn; Davis Strait; Iceland; North Atlantic; Alaska
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.395.1573; http://docs.lib.noaa.gov/rescue/mwr/097/mwr-097-01-0088.pdf

The progression of the planetary waves as reflected in 30-day mean charts at 700 mb that had been occurring during September (Posey, 1968) continued in many areas through October. The mean trough in the Gulf of Alaska intensified further and moved to a position near 145OW (fig. 1). The ridge which had been new the west coast during September progressed to the favored location near the Continental Divide, while the mean trough remained with little change near the Mississippi Valley. The unusually strong closed Lorn south of Iceland deepened further during October while moving slightly southward and phasing with an eastward-moving trough at lower latitudes near longitude 35"W. Blocking, which has been prevalent at high latitudes of the Western Hemisphere for several months, continued during October and became even stronger (figs. 2, 3). Heights at 700 mb were as much as 113 m above normal over the Davis Strait area, while the deep Low south of Iceland produced a 700-mb anomaly of 140 m below normal. Note the easterly components of 700-mb flow over the Arctic Ocean and North Atlantic near southern Greenland (fig. 4). The 30-day mean 700-mb polar westerlies computed between 0 " and 175"W for the latitude belt 55 " to 70"N have been below normal since