Because August temperatures in those two regions reflect the summer position of the North Atlantic jet stream, Trouet and her colleagues used those tree - ring readings to determine the historical position of the jet stream from 1725 to 1978. (sciencedaily.com)
Also inhibiting summer melt this year is the unusually southerly position of the jet stream, caused by a climate pattern called the North Atlantic Oscillation. (wxshift.com)
Indeed on the basis of my previous article about weather being the key it may be possible to get even earlier warning of changes in global temperature trend from observation of the preferred positions of the jet streams and the main high pressure systems. (newclimatemodel.com)