In today's midday 12Z GFS forecast the model delivers an arctic outbreak to the U.S. in 15-16 days. The event is supported by strong stratospheric warming. The outbreak could occur earlier based on the stratospheric warming evolution underway next week.

The convection phase of Madden Julian oscillation (MJO) to the north of Australia is forecast to shift eastward the next 1-2 weeks inducing a west to southwest wind across much of the continent and cause extreme heat risk beginning across Western Australia in the near-term and expanding across the southern tier of Australia in the 8-14-day period.

The latest monthly multivariate ENSO index is -1.1 which indicates a moderate-strength La Nina remains in-place. However, as La Nina enters a 4th year, the MEI observations are following the analog of 3 previous lengthy La Nina episodes and slowly weakening on the way toward El Nino by mid-year.

The warming of SSTA off the West Coast of South America the past 4-6 weeks has suddenly and vividly extended to the Nino12 SSTA region. The Nino12 SSTA is now +1.14C which is nearly 2C warmer than 30 days ago.