Snow Blankets the Eastern United States!
News story originally written on March 5, 2003

This true-color image of the Northeast United States was taken February 20, 2003, two days after record snowfalls blanketed the area. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite took the image. Click on image for full size (786K JPG) Courtesy of NASA

Last year, winter in the Northeast United States was mild with very little snow. This year, however, there is tons of the white fluffy stuff! Several winter snowstorms have rumbled through the Eastern part of the United States, with one in mid-February dumping record, or near record, amounts of snow in Washington, D.C., Baltimore, Philadelphia, New York City, and Boston. In New York City a total of 42 inches has fallen so far this winter. Even more snow has fallen in parts of Massachusetts and upstate New York with total snowfall more than 100 inches in some areas.

Why is there so much snow this winter? The culprit that is bringing this winter weather is called North Atlantic Oscillation, or NAO for short. This climate phenomenon controls the intensity of winter weather with changes in the air pressure gradient between Iceland and the Azores.

The changes in air pressure of the NAO are one of the most common causes of climate variation on Earth. A low-pressure system over Iceland pulls cold air down from the Arctic. It mixes with a high-pressure system that pulls moist air up from the Caribbean. These pressure systems are present more or less all year, but they become stronger and weaker at times. During most seasons they are weak, but in winter they can strengthen. When the pressure difference between the high and low is large, moisture from the high-pressure system hits the cold air from the Arctic and produces many snowstorms, some of which roll towards the East coast of the United States. “It sets up a situation where you’ve got a lot of moisture hitting cold air, and that is a recipe for snow,” says David Adamec, a climate scientist at NASA’s Goddard Space Flight Center.

What can you do about winter weather? Well, you can’t change the weather! But the NOAA National Weather Service recommends that people listen to weather reports on the radio and television to make sure they know what sort of weather may be coming.

This true-color image of the Northeast United States was taken February 20, 2003, two days after record snowfalls blanketed the area. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite took the image. Click on image for full size (786K JPG) Courtesy of NASA

Last year, winter in the Northeast United States was mild with very little snow. This year, however, there is tons of the white fluffy stuff! Several winter snowstorms have rumbled through the Eastern part of the United States, with one in mid-February dumping record, or near record, amounts of snow in Washington, D.C., Baltimore, Philadelphia, New York City, and Boston.

This winter weather has been brought to the East coast of the United States by changing air pressure over the Atlantic, a phenomena called the North Atlantic Oscillation, or NAO for short. The NAO controls how intense winter weather is by changing the high and low air pressure over the Atlantic Ocean.

How does air pressure over the Atlantic cause wintry weather a few thousand miles away in New York? Low air pressure over Iceland pulls cold air down from the Arctic. It mixes with moist air brought up from the tropics by high air pressure over the Atlantic Ocean, west of Spain. The warm moist air hits the cold air from the Arctic producing snowstorms, some of which roll towards the East coast. “It sets up a situation where you’ve got a lot of moisture hitting cold air, and that is a recipe for snow,” says David Adamec, a climate scientist at NASA’s Goddard Space Flight Center. During some winters, these pressure systems can become very strong producing plenty of snow. This is one of those winters!

What can you do about winter weather? Well, you can’t change the weather! But you can be prepared for whatever weather is coming by looking at weather reports on the radio, television, or web.

This true-color image of the Northeast United States was taken February 20, 2003, two days after record snowfalls blanketed the area. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite took the image. Click on image for full size (786K JPG) Courtesy of NASA

Last winter there was very little snow in the Northeast United States but this winter there is tons of the white fluffy stuff! Several huge snowstorms have dumped feet of snow in places like Washington, D.C., Baltimore, Philadelphia, New York City, and Boston.

So what caused all this snow? The answer is in the air! Air may not look like much, but changes in air pressure over the Atlantic Ocean can cause snowy weather a few thousand miles away in New York!

A low-pressure system over the North Atlantic brings cold air down from the Arctic. It mixes with a high-pressure system that pulls moist air up from the warm tropics. The warm moist air hits the cold air from the Arctic producing snowstorms, some of which roll towards the East coast. During some winters, these pressure systems can become very strong producing plenty of snow. This is one of those winters!