Kevin Myatt

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About Kevin

Kevin Myatt grew up in Arkansas to the tune of tornado sirens and the rhythm of hailstones, aspiring to be a meteorologist before his studies and career were turned to journalism instead. Though he often chases storms, he prefers living in the cooler, more tranquil weather of the Blue Ridge. He moved to Roanoke in 1999 to take a job on the copy desk of The Roanoke Times; writing headlines and editing copy is his principal work for the newspaper today.

Each May, Kevin assists Pulaski County High School / Virginia Tech meteorology instructor Dave Carroll in leading college and high school students to the Plains to observe severe weather firsthand. The accounts of many of his storm chases can be found here on the storm chasing page of his weather blog on roanoke.com.

Kevin was an editor for "Hurricanes and the Middle Atlantic States," a book written by D.C.-area weather enthusiast Rick Schwartz and published by Blue Diamond Books that documents hurricanes striking the mid-Atlantic states since colonial times.

The Weather Journal column began in 2003 and appears on Friday's Virginia section front in The Roanoke Times. The Weather Journal blog began in 2006 and follows weather day-by-day between the larger columns.

Missing ice might put our winter weather on hold

Courtesy of University of Illinois

The maps above, based on satellite data, display the ice concentration in the Arctic Ocean on Oct. 11, 2006, (top) and Oct. 11, 2007. Purple represents sea ice, and white denotes snow cover on land. North America is at the left, the Bering Strait between Alaska and Russia is at the top,  Asia is at the right, and the north pole sits near the center of the maps.

Here in the Northern Hemisphere, we are moving through autumn toward winter, but the Arctic Ocean is still largely unfrozen.

The accompanying graphics compare the coverage of Arctic ice on Oct. 11, 2006, with that of the same date this year. Notice the large area of unfrozen ocean near Alaska and Siberia at the top of the map.

The National Snow and Ice Data Center reported last month that ice coverage over the Arctic Ocean fell below 2 million square miles for the first time on record. By comparison, the United States covers about 3.5 million square miles.

The record only goes back to when satellite data on Arctic ice began in 1979. Many scientists believe this is the lowest level of ice in several centuries, and some believe it is the lowest in recorded human history. But the hard, verifiable data only go back to 1979.

The lack of ice this particular summer and fall is almost certainly related to unseasonable warmth that developed over parts of Russia and spread eastward. High pressure over the Arctic kept clear skies and bright sun over the region much of the summer, and offshore winds pushed warmth from inland Siberia into the ocean, the National Snow and Ice Data Center reported.

It may also be related to the long-term rise in global average temperature, popularly known as global warming.

A United Nations panel earlier this year concluded that there was a 90 percent chance that man-made emissions of greenhouse gases such as carbon dioxide are the primary cause of global warming. Vocal skeptics point to natural cycles, such as recovery from the "Little Ice Age" that dominated the past few centuries.

Let's bring ourselves to 2007 and early 2008 for the purposes of this column. I'm going to focus on what this particular year of low Arctic sea ice could mean for the coming winter.

Strictly speaking, the onset of cooler temperatures in the fall and winter is not caused by ice forming in the Arctic. Temperatures cool because the tilt in the Earth's axis gradually moves the Northern Hemisphere away from the sun during our fall and winter.

The days get shorter and the sun angle lessens until the sun is below the horizon for months near the north pole. The lack of sun means the air does not absorb heat, circulation patterns move that cooler air gradually southward, and winter slowly overspreads North America, Asia and Europe.

But what ice and snow cover can do is allow cold air masses to build over them, becoming thicker and more intense. These deeper Arctic air masses move south in winter and bring our rounds of subfreezing temperatures, which, if they meet up with enough moisture, bring snow and ice.

With this much of the Arctic still unfrozen, more of the early season cold air will be used up freezing the ocean rather than building in the atmosphere and moving southward. What's more, the process of freezing releases a slight amount of latent heat into the air.

But there is a paradox: An unfrozen Arctic Ocean increases the threat of snowfall on some surrounding land masses. Storm systems will be able to draw in much richer moisture from an unfrozen ocean than from an ice sheet.

The accompanying maps actually show that snow cover, in white, is thicker and more expansive over eastern Alaska and northwestern Canada than it was a year ago.

Canadian snowpack helps Arctic air masses reach the U.S. more easily and can sustain them longer.

Also notice that the Arctic is much more frozen in northern Canada and around Greenland than it is near Alaska and Siberia. Closer to us, there is more ice.

So an overall prognosis: Winter may get off to a slow start in the Northern Hemisphere as the Arctic refreezes later in the season than normal. But if the snowpack continues to grow and deepen over Canada, and Arctic air begins to build over the ice-covered areas of northern Canada, the U.S. will probably see some intensely sharp cold snaps.

From the Pacific, there is still La Nina to deal with, and its propensity to create mild, dry winters over the southern half of the country. But a La Nina pattern usually has a few intermissions. Those intermissions could be the most entertaining part of the show this coming winter.

On the Net: National Snow and Ice Data Center nsidc.org University of Illinois Arctic Climate Research arctic.atmos.uiuc.edu

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