The start of tropical cyclone season is just a few days away and the North Atlantic basin is the warmest on record (+1.06C). The implied upper ocean heat to fuel tropical cyclones is immense. Additionally, the widespread anomalous warmth also indicates sea level rise especially neat the U.S. Coastline.

The daily North Atlantic basin sea surface temperature anomaly (SSTA) is +0.94C and implies the Atlantic multi-decadal oscillation (AMO) is similar and therefore easily a record warm value for May. The North Atlantic basin has warmed 0.23C during the past 7 days. A primary contributor is the tropical North Atlantic (TNA) index located across the main development region (MDR) for hurricanes. The daily TNA index is +1.46C maintaining the record warm signature in this part of the outer tropical North Atlantic basin.

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.