Under the Weather | Annie Lu

Under the Weather

by Annie Lu

As residents of idyllic San Diego, where the sun is always bright and smiling and the sky is always summer baby blue, we don’t experience much cold weather. Many weather reports hitting the news recently spoke of a horrific winter temperatures seizing the northern hemisphere. A storm system that swept through the coastal Southeast at the late end of December strengthened into what’s called a “bomb cyclone” threatening the East Coast.

“A storm is a bomb—or bombogenesis happens—when it drops 24 millibars [a measure of pressure, or force exerted by the weight of air] of pressure in 24 hours. This storm looks like it will intensify twice that rate,” said Bob Oravec, lead forecaster at the National Weather Service’s Weather Prediction Center. The storm brings with it furious winds that can lead to blizzard conditions and coastal flooding. Bombogenesis is not unheard of, and are estimated to occur about ten times a year, but this storm, named Grayson, is atypical for several reasons.

Grayson happens to be the “perfect alignment of the three things [meteorologists] look for.” That is, a warm conveyor belt of tropical moisture, which the Gulf Stream is funneling out of the Caribbean; an enormous sub-zero mass of air dropping down from the Arctic; and a large temperature contrast across the center of the storm, which leads to differences in pressure, which in turn allows air to rush in. “The faster [the pressure] drops, the faster the air moves. And thus, a winter storm is born.”

Meteorologists are seizing upon this rare opportunity of a winter storm to learn more about them: they want to know how much of a power boost winter storms draw from rapidly-warming oceans. The occurrence of Grayson is a confirmation of a controversial prediction from climate scientists, that a reduction in sea-ice and Arctic warming causes the Arctic cold to drift downwards towards the lower continents. This means global warming’s influence on an increase in extreme weather events includes those bringing in huge cold snaps.

The bomb cyclone naturally posed a danger to many people, especially travelers. Flooding at the JFK International Airport brought into focus infrastructure concerns; the Norwegian Cruise Line suffered as some ships sailed right through the winter storm, turning bathrooms into popsicles and angering passengers. In Florida, near-frozen iguanas were known to fall from trees. More commonplace concerns include damaging high-speed winds and dangerous coastal flooding. Grayson is an easy way to get frostbite, hypothermia, or become involved in a cold-weather-related traffic accident. By the first week of January, 11 people had already died in the outbreak of cold. This storm will culminate in one of the coldest holiday seasons on record for the East Coast. Storms like this actually serve an important climatic function, “as they help redistribute pockets of heat and cold more evenly from the globe,” says atmospheric scientist Jeff Frame.