A combination of new and established marine heat waves were significant contributors to an upper air pattern responsible for delivering historic flooding in far southeastern Brazil and equally impressive cold in Western Russia during the past 2-3 weeks. An emerging and progressive convection phase of the Madden Julian oscillation should ease this pattern during late May.

High pressure is forecast to extend across much of the West U.S. during JUN/JUL 2024 with a weak upper trough in the East. The combination of these two pressure centers will leave most of the U.S. with below normal wind speeds for the first half of summer 2024. There are a few exceptions such as Northern California, Southern Texas, and the Carolinas where wind speeds are greater than normal.

Last week the Nino34 SSTA dipped below the (+0.5C) El Nino threshold. ENSO is now officially in neutral phase. Only the Nino4 SSTA region (near the Dateline) is above the El Nino threshold.

In Southeast Brazil, the 15-day forecast is unrelenting as more excessive rain is indicated. GFS projects >10 in. of rain during the next 15 days in Southeast Brazil. The widespread damaging flooding episode in the Southeast Brazil State of Rio Grande Do Sul began in late April and will continue well into May.