Are the "polar vortex" and "cut-off lows" over/near the Great Lakes new phenomena?

Question

In recent years, I've heard weather reporters describe "cut-off" low pressure systems which park over Southern Ontario for days at a time. In summer months, they bring us long stretches of cool cloudy, often rainy days. In only the last couple of years, there was mention of the "polar vortex" which seemed to unusually extend and deepen our winter last year. I don't recall mention of either term in weather reports for the Southern Ontario region more than a few years ago. Over the meteorological record for this region, are these new patterns? If they are not new patterns, is it simply a trend in weather reporting to apply these terms?

Answer 1

The "polar vortex" hype is definitely a result of the media. The "polar vortex" is an upper air feature that does not make it to the surface, but can have some repercussions on surface weather. The media has portrayed the "polar vortex" as a monster coming to get you when it intrudes southward quite regularly...and has been for a long-long time.

As to cut-off lows over Ontario, this, likewise, is not a new phenomenon. When a mid-latitude cyclone becomes cut-off, it simply means that it has moved far enough away from the jet stream to not be affected by it. Since the jet stream can bring divergence aloft to the cyclone, the low is now cut-off from air exiting at the top. This means the pressure at the surface will begin to rise and eventually lead to the decay of the system.

There has been some research done over the effects that The Great Lakes have on cut-off cyclones. They seem to hang around The Great Lakes region. My professional opinion is that the diabatic heating (heat transfered from the warm lake to the atmosphere) keeps the cyclone alive for longer. Also, since the cyclone is cut-off from the jet stream, it will not have a lot of forward motion and may sit over a location for a while.