With the coming of Meteorological Winter next week I thought I would give a quick reminder of what the polar vortex is. A polar vortex is an upper-level low-pressure area lying near the Earth’s poles. There are two polar vortices in the Earth’s atmosphere, overlying the North and South Poles.
The breaking off of part of the vortex is what defines a polar vortex event. But it actually occurs when the vortex is weaker, not stronger. That might sound weird—but it actually makes sense. Normally, when the vortex is strong and healthy, it helps keep a current of air known as the jet stream traveling around the globe in a pretty circular path. This current keeps the cold air up north and the warm air down south.
But without that strong low-pressure system, the jet stream doesn’t have much to keep it in line. It becomes wavy and rambling. Put a couple of areas of high-pressure systems in its way, and all of a sudden you have a river of cold air being pushed down south along with the rest of the polar vortex system.
Recent research has found the very upper part of the atmosphere, called the stratosphere, can suddenly warm up. The temperature may warm over 100 degrees in just a few days at an altitude of 50,000 feet. These rapid warming periods are called Sudden Stratospheric Warmings (SSW).
The SSW triggers movement of arctic cold air at the surface. The stratosphere warms, expands and pushes on the Polar Vortex. The Polar Vortex gets “disrupted.” The Polar Vortex will then move off the North Pole and shift southward.
Wow! We have a colorful warning and hazards map from the NWS the morning – the pinks and blues denote snow warnings and watches which stretch from the U.P. all the way to the west coast. The tan colors are high wind warnings and watches which stretch from Michigan to New Mexico. We have a high wind watch for a good portion of lower Michigan along with a lakeshore flood watch all going into effect tomorrow at 7am.
From the NWS: We still expect the strongest winds to be along Lake Michigan south of Grand Haven with wind gusts of 50 to 60 mph by late morning through the afternoon. Further north and inland we expect wind gusts peaking at 45 to 55 mph. This will be a stronger and longer-lasting wind event than the storm last week, causing more power outages and worse beach erosion than that storm.