UD C 551.503.1:551.513(73)"1973.O7" WEATHER AND CIRCULATION OF JULY 1973 Cool and Wet in the Middle Third of the Country But Increasing Drought in the Northwest

• Main Authors: A. James, National Weather Service
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Bering Strait; Canada; Taymyr; Davis Strait; Taymyr Peninsula
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.395.2412; http://docs.lib.noaa.gov/rescue/mwr/101/mwr-101-10-0777.pdf

The middle-latitude 700-mb zonal westerlies remained stronger than normal during July, but both their absolute value and the magnitude of the anomaly decreased in July. This change was due mainly to weakening of both the Aleutian and Icelandic Lows, which had been unusudly strong during June (Taubensee 1973). The suhtropical ridge over the Padific remained stronger than normal, while the Bermuda-Azores ridge amplified to as much as 70 m above normal over the central Atlantic (figs. 1, 2). Over North America, the middle latitude portions of the trough, which in June had extended from the Davis Strait to Texas, advanced to a position near the 7OoW meridian (fig. 1). Remains of the lower portion of the trough were reflected in a break between the two subtropical ridges and a weak negative anomaly over west Texas. At high latitudes, the intense polar vortex progressed 90 ' of longitude from its location near the Taymyr Peninsula to about 17OoW, accompanied by a fall of S8 m in the mean 700-mb height anomaly from June to July north of the Bering Strait (fig. 3). Blocking remained over northwest Canada, although it became less pronounced FIGURE 1.-Mean 700-mb height contours in dekameters (dam) for July 1973.