Historic Intense Positive Arctic Oscillation

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Friday’s Mid-Atlantic Tornado Event Explodes into 930 MB Low Pressure in Northern Atlantic over The Weekend

Fig. 1: One of the strongest daily positive arctic oscillation index observations on record occurred yesterday.

Discussion: The developing low pressure system over New England last Friday intensifying to 965 MB low on the upper Maine Coast Friday evening was responsible for the historic tornado outbreak across the Mid-Atlantic and powerful hurricane force gusts that followed for the entire Northeast Corridor. However, as the low pressure traveled northeastward into the polar vortex positioned just east of Greenland the low pressure system intensified to a 930 MB equivalent to a category 4 hurricane. As a result the daily arctic oscillation spiked at >+6 which is one of the strongest daily positive phases observed.

The intensifying low brought widespread hurricane force wind to northwest Europe and 3-7 in. of rain for many locations near the coast. Records were set for trans-Atlantic flights from New York City to London. Jet stream speeds have lowered since yesterday but are still 200-210 mph across the North Atlantic.

The 15-day arctic oscillation forecast averages +3.4 after the 3rd strongest +AO on record for January (+2.415). Only 1989 had a stronger JAN/FEB positive phase arctic oscillation. Interestingly, the JAN/FEB 1989 +AO occurred as an exceptionally strong solar maxima was developing. In 2020 just the opposite is occurring…an unusually strong solar minima.

Fig. 2-3: A powerful polar vortex present the past 2+ months intensified again over-the-weekend…this time in the vicinity of Greenland. The intensifying polar vortex spawned a 930 MB low pressure system yesterday, now 945 MB on the coast of Norway.

Fig. 4: The intense polar vortex has spawned jet stream winds >250 mph (yesterday) settling to 200-210 mph this morning.