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Anomalously warm water dominated much of the North Pacific Ocean for the past year, first observed in October 2013 as a mass of warm water extending 30 degrees of longitude and 8 degrees of latitude, centered on the dateline at ~40°N. This warm water mass shifted east in November to 45°N and 155°W and to 45°N 140°W by December where it was more or less centered through summer 2014 (Fig. 1). In January 2014 (as reported by Freeland and Whitney, 2014), SST anomalies were +3°C above the longterm (1982-2014) seasonal average and centered at 42°N 148°W. This warm water mass expanded longitudinally during the summer months of 2014 such that anomalously warm waters were seen in the Bering Sea and west into the Sea of Okhotsk (Fig. 1). Throughout this period, +3°C anomalies persisted. Not only was the northern North Pacific anomalously warm, but +2°C temperature anomalies persisted off the coast of Baja California, Mexico, and into southern California throughout the summer of 2014. This was not a shallow puddle of warm water - rather the layer was thick - along Line P, warm water was found to depths of 100 m in February 2014 (PICES Press, Vol. 22, No. 2) and had not changed during the June 2014 Line P cruise (Fig. 2).
It can be safely said that this warming event was unprecedented. What looked initially like a major El Niño event was clearly not, and was not related in any way to conditions at the equator. For scientists in North America, this mass of warm water has been fondly named "the blob" by the State Climatologist of Washington State (Nick Bond). This term is now in common usage.
The unusually warm sea surface temperature (SST) in the NE Pacific is linked to a highly anomalous sea level pressure (SLP) weather pattern. During October 2013 through January 2014, much higher than normal SLP was present over the northeastern Pacific (Fig. 3), with a peak magnitude approaching +10 hPa. For the region of 5545°N, and 150-130°W, this was a record high value for the years 1949-2014 (about 2.6 standard deviations above normal for the 4 month period) with the next largest value being about 2.2 standardized units above normal during October 1978-January 1979....