The Weather and Circulation of July 1967Unusually Cool East of thc Divide
From June to July progression of long wave features at middle and high latitudes was observed throughout the Western Hemisphere. This progression can be viewed within the context of the zonal wind profile at 700-mb. (fig. 1). The profile displays stronger than normal westerlies north of 47.5"N....
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| Format: | Text |
| Language: | English |
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1967
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.395.2290 http://docs.lib.noaa.gov/rescue/mwr/095/mwr-095-10-0700.pdf |
| Summary: | From June to July progression of long wave features at middle and high latitudes was observed throughout the Western Hemisphere. This progression can be viewed within the context of the zonal wind profile at 700-mb. (fig. 1). The profile displays stronger than normal westerlies north of 47.5"N. latitude and weaker than normal westerlies south of that latitude. Thus, progression appears related to decreasing upper level heights over the Arctic from June to July as R blocking ridge retrograded to north-central Asia (figs. 2, 3). Retrogression of this blocking ridge has been a long term phenomenon which began in mid-April in the Aleutians. As the block moved from its June position over northeastern Asia, the Asiatic coastal trough, which had been strong only in the south during June [I], opened to the north and progressed during July. The west Pacific ridge, which also had been suppressed by high latitude blocking during June, progressed and amplified strongly during July. From this feature eastward to Europe, progression of nearly all long wave features in the westerlies can be noted from June to July. In the vicinity of North America this resulted in essentially a reversal of June's long wave distribution with troughs replacing ridges along the west coast and in eastern North America and ridge replacing trough in the Far West. The fast westerlies over the Atlantic during June [I] diminished markedly during July as an amplifying ridge moved into the western Atlantic. East of this ridge a strong trough moved into the eastern Atlantic while June's ridge near the British Isles moved over the Continent. Over Asia, marked deepening took place at middle latitudes to the south of the retrograding blocking ridge. 2. TEMPERATURE Progression of long wave features in the vicinity of North America was associated with marked temperature changes in some parts of the United States. The strong mean ridge over the Rockies brought above normal temperatures to most areas west of the Continental Divide (fig. 4), replacing lorn ... |
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