This graph shows is a “Stratospheric Warming Event” now occurring. The lower black line shows the lowest temperatures recorded up at the 10 mb level recorded on this date, and the upper line shows the highest temperature at that level recorded on this date. What the red line shows is that we moved from the lowest recorded to the highest recorded in a matter of days, even hours.
When it warms this dramatically up in the stratosphere it often results in cold temperatures down in the lower Troposphere in New Hampshire, where I live.
I’m not exactly sure of the dynamics, or why warming way up above the North Pole changes the weather way down low and way south of the pole. As best as I can tell, through some cause-and-effect, (and I’m not saying which is the chicken and which is the egg,) a zonal pattern, which locks cold air up at the pole, breaks down during Stratospheric Warming Events, unlocking the cage created by a zonal flow, and allowing the wolves of winter to howl south.
Drat. And I still haven’t remembered where I put my hat and scarf.