Evolution of a titanic negative North Atlantic oscillation (-NAO) pattern is indicated during the medium-range. The effect of -NAO is to produce anomalous upper-level high-pressure blocking over Greenland. The high-pressure block is certainly evident in the “most likely” upper air forecast for the northern hemisphere by the mega-cluster ensemble.

In a worse case scenario, the evolving cold pattern in Western Russia is trending stronger and is now more expansive into Europe likely reaching U.K. in the medium range. The Canadian Ensemble most effectively illustrates the cold risk.

Forecast models reveal presence of MJO convection concentrated near the Dateline through the weekend surging eastward toward and into the equatorial Atlantic in early December. The influence on climate is heavy rainfall across the Mid-south (and vicinity) in the 10-day U.S. precipitation outlook, enhanced rains across Brazil, and a rare drying trend in Australia.

Getting the most (research) attention regarding a new phenomenon referred to as marine heat waves (MHW) is typically the Northeast Pacific MHW and more recently in research published in Journal of Climate, the East Asia/West Pacific MHW. However, the southern hemisphere has certainly acquired large areas of surface/subsurface water much warmer than normal and well-correlated to upper atmosphere pressure patterns somewhat stagnant in character leading to long lasting climate regimes featuring both very wet and dry-to-drought regimes.