The combination of an impressive warm ENSO and positive Indian Ocean dipole is forecast by the Australia Bureau of Meteorology for JUL/AUG/SEP 2023. If so, analogs emphasize a strong upper ridge across Europe returning the dry/hot regime observed last year biased slightly farther eastward.

A powerful Madden Julian oscillation is in the 15-day forecast by all models. The MJO shifts across the equatorial Pacific to ignite a weather pattern change across the northern hemisphere plus erode what remains of La Nina and point ENSO in the direction of El Nino for mid-year.

The most recent example of devastating climate regimes and embedded weather events is across New Zealand as summer 2022-23 has produced historic warmth across South Islands while Northern New Zealand has endured the worst flooding episode on record. The catalyst to the heat and flooding rainfall is the persistence of anomalous warm waters which reached record levels in early 2023 surrounding New Zealand.

A very specific set of circumstances convened during late December 2022 and intensifying in early January 2023 to cause what eventually became an “atmospheric river” storm track targeting California for a 3-week period of excessive rainfall (over 50 in. for some locations) and 10’s of feet of snow across the Sierra Nevada.