National Aeronautics and Space Administration

During the week of 8-14 February 2016, cold air swept down across the eastern half of the US. During this event the tropospheric jet stream also moved down across the southern US (an upper tropospheric trough). Associated with these tropospheric changes, the stratospheric polar vortex also changed dramatically from initially being located over the Asian continent to moving over the US upper tropospheric trough. The relocation of the stratospheric polar vortex created strong stratospheric flow from over the North Pole directly to the US. These major changes in the atmospheric circulation were captured in the NASA GMAO 10-day global forecast system. Read more.