Majority of forecast models are indicating La Nina development by early-to-middle quarter 4 of 2024. Some models are maintaining neutral ENSO. Current diagnostics favor neutral ENSO. Forecast models are more agreeable to the presence of -IOD. The comparison between -IOD/weak ENSO and La Nina coupled with -IOD yield differences but nothing profound. In general, the -IOD/LA Nina regime offers a wetter solution for Brazil.

As of mid-May, the U.S. severe weather season has produced the second-most number of tornadoes so far, and second only to 2011. The upper air pattern during MAR/APR/MAY 2024 (so far) has featured a persistent upper trough over the Southwest U.S. forcing the subtropical jet (STJ) stream to arc northeastward across Mexico to the Southeast U.S. inspiring low-level jet (LLJ) streams forcing buoyant moisture northward from the warmer than normal Gulf of Mexico. The intersection of the upper-level high wind band over a lower atmosphere channel of warm moist air is causal to severe weather.

Is the wet May pattern in the eastern half of the U.S. anomalous? No, the wet pattern is likely to continue during the summer months for much of the eastern half of the nation. Tricky is the wet East/dry West dividing line as relevant to U.S. Crop Areas. The U.S. Corn Belt and soybean growing areas may be centered on that dividing line which can cause havoc to agriculture analysts, planners, and traders as crop conditions vary widely.

An extreme rainfall event has occurred in Rio Grande do Sul in Southeast Brazil leaving thousands homeless, many people killed, and widespread destruction such as washed-out bridges and destroyed homes. The rainfall event is ongoing and additional extreme rain is likely into mid-May. Why?