Historic cold in the U.S. with 80-year record heat in Australia while conventional storms bring 100 mph wind to New Zealand and Switzerland...why? An unusually strong negative phase of the global atmospheric angular momentum index.
Sydney, Australia roared to 117F over-the-weekend, the hottest day in 80 years. Foreshadowing this event is the super warm ocean surface east of Australia. More super heat for eastern Australia is likely for summer 2017-18!
The arctic air reservoir across the Midwest/Northeast U.S. this afternoon is set to be replenished over the next 2 days pulled southward by a developing storm off the Mid-Atlantic/Northeast coast. The developing storm will be quickly unusually intense due to the replenishing arctic chill across western North Atlantic SSTA averaging 1-3C warmer than normal.
The evolving extreme cold developing across the U.S. and likely to last 7-10 days was not caused by any particular climate diagnostic. However, a look at solar activity offers a possible link. Solar activity is currently entering the 11-year minima about 1 year faster than forecast. The last solar minima which was unusually strong and of long duration produced cold to very cold mid-latitude winter seasons.