Fig. 1-2: The North Atlantic Warm Hole shifts toward Europe in May. Note the cool SSTA change in May.
Fig. 3: The May 2021 upper air trough across Europe.
Fig. 4-5: The May 1-25 temperature and precipitation anomalies across Europe.
Discussion: Potentially due to the slow-down of the Atlantic Meridional Overturning Circulation (AMOC) and the natural variability of the Atlantic multi-decadal oscillation (AMO) and North Atlantic oscillation (NAO) the North Atlantic “cold blob” also known as the North Atlantic warm hole (NAWH) shifted east toward Europe in May and is responsible for an unusually cold and wet May Europe climate. The NAWH became more enhanced in 2013 and has been semi-permanent south-southeast of Greenland since that time. The eastern displacement toward Europe in May is the farthest east shift in the 2013-2021 climatology. In the 2013-2021 climatology 500 MB anomaly analysis reveals a persistent upper trough over this “cool blob” region. The upper trough shifted east and across Europe in May to deliver one of the coolest and wettest late spring climate patterns on record.
Interestingly, emergence of the “cool blob” in the North Atlantic occurred simultaneously with the “warm blob” in the Northeast Pacific. The persistence of these two SSTA regions is well-correlated to a persistent upper-level high-pressure ridge in the Northeast Pacific and upper-level low-pressure trough south of Greenland. Climate Impact Company is of the opinion these regional SSTA influences have become leading models of climate influence on North America and Europe climate.
Fig. 6: The 2013-2020 northern hemisphere upper air pattern identifies the most prominent features across/near the Northeast Pacific “warm blob” and North Atlantic “cool blob”.