So far, May 2023 has produced below normal zonal and meridional wind speeds across the U.S. particularly across most of the SPP and ERCOT regions of the Central U.S. Causal to the lack of wind is a large area of high pressure over Western Canada extending to the Great Plains and generally weak low pressure in the far southern States to the East Coast.

What is the North Atlantic warm hole (NAWH)? Since 2013, the NAWH pattern has strengthened due to accelerated presence of freshwater snow and ice melt from Northeast Canada and Greenland deposited into the Labrador Sea and eastward/southward most noticeable during MAY/JUN but generally present most of the year. During the past 10 years, the cool ocean waters have caused a cooling of the middle troposphere where a semi-permanent upper trough has generated. During the past 30 days, the trough has amplified off the Southeast Canada Coast and extended into the East U.S. bringing a cool late spring.

Once again, marine heat waves are in the news as a catalyst to a major weather event. A large MHW off the Northwest Africa/Southwest Europe coast the past few months shifted westward the past couple weeks and the latent heat loss where the warm SSTA pattern was previously located (central/west Mediterranean Sea) deepened an upper-level storm that caused "apocalyptic" rains from Italy to Bosnia the past few days.