3rd strongest “warm blob” on record emerges Northeast Pacific Ocean. If persistent, could lead to a “polar vortex” mid-winter pattern. Climate Impact Company winter 2020-21 outlook issued Friday. Fig. 1:  A marine heat wave (MHW) associated with a large region of oceanic warming has emerged in the northeast Pacific Ocean. Known as the “warm blob” first recognized in 2014, the current episode is 3rd strongest on record. Fig. 2-3: The strongest and second strongest MHW (or “warm blob” episodes) on record occurred in 2014 and 2019. Discussion: What is a marine heatwave? MHW’s occur when ocean temperatures are much warmer than normal for an extended period of time. MHW’s became a new ocean/climate field of study following the sudden and unexplained warming of the northeast Pacific in 2014. An area of warming which became known as the “warm blob”. The strongest “warm blob” (or MHW) occurred in 2014, the second strongest in 2019 and 3rd strongest on record emerged this month (Fig. 1-3). There is a general ocean-to-climate relationship of the “warm blob” that favors high pressure ridging on the West Coast of North America and a downstream upper trough across central or eastern North America. This relationship is a contributor to unusually dry climate in western North America and during winter promotes cold outbreaks into the U.S. We need to watch the September 2020 “warm blob” closely as to potential effects on the winter ahead North America climate pattern (and downstream influences on Europe). If the “warm blob” persists and ALL global SSTA forecast models indicate that possibility is likely, there should be a tendency for increased incidence of upper ridge patterns on the U.S. West Coast and downstream troughing into the central and/or eastern U.S. La Nina has formed in the eastern equatorial Pacific. During a La Nina winter there is a tendency for a cold climate featuring increased risk of arctic air in Western Canada. If the “warm blob” induced upper ridge pattern over western North America is semi-permanent this winter season, delivery of that cold air in the Western Canada source region to the U.S. will occur with important frequency. Fig. 4: The January 2021 global SSTA forecast by ECMWF maintains the northeast Pacific “warm blob” which could induce a polar vortex upper air pattern for mid-winter.   Fig. 5-6: The January 2021 upper air forecasts indicate a moderate-to-strong presence of the polar vortex affecting the northern U.S. and representing a cold and snowy influence for mid-winter.