Faster than normal trade winds are normally associated with a temperature inversion usually around 850 MB (about 1,500 meters). The temperature inversion prevents vertical motion enabling convective cloud formation associated with developing tropical disturbances. Since July 1st, trade winds have been much faster than normal across the North Atlantic tropics.

Based on a constructed analog combining optimum climate normal and ENSO analog years the upper air pattern for North America for each month of meteorological winter 2024-25 is projected. Revealed is low risk of a “polar vortex” pattern during December or January. However, a broad polar vortex pattern is forecast across Southern Canada during February.

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.