‘The Blob’ - or, how unusual were ocean temperatures in the Northeast Pacific during 2014-2018?

Strongly positive sea-surface temperature anomalies developed in the Northeast Pacific Ocean during the winter of 2013/14. Sea-surface temperature anomalies near Station Papa, in the Gulf of Alaska, were more than 4.5 standard deviations above normal. Temperature anomalies in excess of 4 standard deviations were still present subsurface into 2017. Such departures from climatology raises this event from unusual to extraordinary. On the principle that an extraordinary observation needs extraordinary proof, in this paper we examine three datasets that are completely independent of each other and examine how closely those datasets correspond with each other. The correspondence is found to be close. We also discuss the statistical interpretation and probability that a 4.5σ departure from normal can occur.