The Arctic Oscillation (AO) is currently neutral and will remain near neutral most of the week before trending negative over the weekend, after which the AO is predicted to remain negative for the foreseeable future.
The negative AO trend is reflective of the positive pressure/geopotential height anomalies consolidating in the Arctic especially on the North Atlantic side while pressure/geopotential height anomalies slowly fall across the mid-latitudes of the North Atlantic sector including Western Europe and eventually the Eastern United States
The return to a negative AO atmospheric state is in response to the stratospheric warming (SSW) that had a minor peak the second week of February but will have a larger peak in March that will result in a major warming.
The very active vertical energy transfer this winter is not done just yet as more pulses are predicted for the first half of March. So while these pulses are leading to extreme negative AO values in the stratosphere they are delaying similar negative AO values in the troposphere.
The polar vortex (PV) is currently split over northern Eurasia and is predicted to split even further over the Eurasian continent. With the PV displaced so far south over the Eurasian continent that is where the largest negative temperature departures are expected for the month of March. With one lobe of the PV predicted to be over Siberia that is where the most extreme cold temperatures are expected.
However a second lobe is predicted over Europe that should bring relatively cold weather to Europe as well.
With the lack of any direct influence from the PV and with the vertical energy transfer still active, temperatures should average relatively mild for North America for the first half of March.
However the AO could potentially turn more sharply negative in the second half of March in response to the major warming in the stratosphere and temperatures in the Eastern United States could therefore turn colder as well.
Kort samengevat. De grootste negatieve temp afwijkingen in Eurasia in Maart, maar ook Europa zal relatief koud zijn.
Noord Amerika eerst zacht daarna koeler in het oostelijk deel.
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