Winter Extremes

Jan. 3, 2018

A polar vortex is an area of low pressure—a wide expanse of swirling cold air—that is parked in Polar Regions. Sometimes this low-pressure system, full of cold Arctic air, strays a little bit too far from home. Part of it can break off and migrate southward, bringing all of that cold air with it. 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.

Meteorologists are predicting an unusual polar vortex event called a cyclonic bomb for later in the week. A powerful storm will hammer coastal locations from Georgia to Maine with ice and snow. By Thursday, the exploding storm will, in many ways, resemble a winter hurricane, battering easternmost New England with potentially damaging winds in addition to blinding snow.

Some computer models are projecting a minimum central air pressure of below 950 millibars at its peak, which would be nearly unheard of for this part of the world outside of a hurricane. For comparison, Hurricane Sandy had a minimum central pressure of about 946 millibars when it made its left hook into New Jersey in 2012. Winds will crank in response to this pressure drop, howling to at least 30 to 50 mph (48-80km/h) along the coast. The storm's enormous circulation will help draw several lobes of the polar vortex, the zone of frigid air meandering the North Pole, over the Mid-Atlantic and Northeast by Friday and Saturday. Wicked cold air sourced from Siberia, the North Pole and Greenland will all converge on the region. Winds will be considerably stronger over the ocean - exceeding hurricane force where enormous waves will form. Temperatures are forecast to be 20 to 40 degrees below normal, the coldest of the winter so far. Temperatures in Florida will be higher than temperatures in Alaska.

While it may seem counterintuitive, the scientists believe these bitter cold snaps are connected to the warming of the Arctic and the effects that that warming is having on the winds of the stratospheric polar vortex, high above the Earth's surface. The evidence is clear that the Arctic is warming faster than the rest of the planet. That warming is reducing the amount of Arctic sea ice allowing more heat to escape from the ocean. The scientists think that the ocean energy that is being released is causing a weakening of the polar vortex winds over the Arctic, which normally keep cold air centered over the polar region. That weakening is then allowing cold polar air to slip southward more often.

So, the warming of the atmosphere and oceans in Polar Regions can cause more extreme winter weather at mid-latitudes. To the uninformed, extremely cold winter weather is ‘proof’ that global warming is a hoax perpetuated by the majority of scientists on the planet. This also shows the importance of scientific literacy in dealing with complex environmental issues such as climate change. Understanding how all the variables interact requires understanding of complex scientific processes, which is difficult for the ideologically driven climate change deniers. The fact that less ice means a dip in the jet stream bringing Arctic weather to Canada, the United States, Siberia and Europe is further evidence of climate change. Unfortunately for the deniers, it becomes a misinformed tool for the ignorant. Climate change means the planet will experience more extreme weather. In the winter, that means more extreme cold and snow.