Arctic Oscillation and Polar Vortex Analysis and Forecasts

 

May 15, 2024

Dr. Judah Cohen from Atmospheric and Environmental Research (AER) embarked on an experimental process of regular research, review, and analysis of the Arctic Oscillation (AO) and Polar Vortex (PV). This analysis is intended to provide researchers and practitioners real-time insights on one of North America’s and Europe’s leading drivers for extreme and persistent temperature patterns.

During the winter schedule the blog is updated once every week. Snow accumulation forecasts replace precipitation forecasts. Also, there is renewed emphasis on ice and snow boundary conditions and their influence on hemispheric weather. In late Spring, we transition to a spring/summer schedule, which is once every two weeks. Snow accumulation forecasts will be replaced by precipitation forecasts. Also, there will be less emphasis on ice and snow boundary conditions and their influence on hemispheric weather


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The AO/PV blog is partially supported by NSF grant AGS: 1657748.

Summary

  • The Arctic Oscillation (AO) is currently positive and is predicted to trend negative towards neutral later this week as pressure/geopotential height anomalies across the Arctic are currently mostly negative but then pressure/geopotential height anomalies across the Arctic turn more mixed. The North Atlantic Oscillation (NAO) is currently positive with mostly negative pressure/geopotential height anomalies across Greenland and the NAO is predicted to trend negative the next two weeks as pressure/geopotential height anomalies turn more mixed to positive across Greenland.
  • Weak troughing/negative geopotential height anomalies across Greenland will generally support ridging/positive geopotential height anomalies across Northern Europe with weak troughing/negative geopotential height anomalies across Southern Europe the next two weeks. This pattern will support normal to above normal temperatures across Northern Europe including the United Kingdom (UK) with normal to below normal temperatures across Southern Europe the next two weeks.
  • The next two weeks general ridging/positive geopotential height anomalies predicted across Northern Europe and then Northwestern Asia will support troughing/negative geopotential height anomalies across Northern and Eastern Asia with more ridging/positive geopotential height anomalies across Southern Asia. This pattern favors normal to above normal temperatures across Western and Southern Asia with normal to below normal temperatures across Northern and Eastern Asia the next two weeks.
  • The predicted general pattern across North America the next two weeks is ridging/positive geopotential height anomalies across Alaska, Northern and Eastern Canada and the Eastern United States (US) forciing troughing/negative geopotential height anomalies across Southwestern Canada and the Western US. This pattern favors normal to above normal temperatures across Alaska, Northern and Eastern Canada and the Eastern US with normal to below normal temperatures across Southwestern Canada and the Western US the next two weeks.
  • In the Impacts section I discuss the upcoming pattern and how it may influence weather across the Northern Hemisphere (NH).

Plain Language Summary          

Episodic cooler and/or wetter temperatures is predicted to continue in parts of the US, Europe and Asia the second half of May thanks in part to high-latitude high pressure ridging in late May (e.g., Figures 3 and 4).  This does seem unusual to me, and our summer weather will be impacted by how long the high-latitude high pressure ridging can persist in the summer months.

Impacts