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Large-scale storm systems are the dominant weather phenomenon during the cold season in the United States. Although the analysis of these storms is complicated by a relatively short length of most observational records and by the highly variable nature of strong storms, some clear patterns have emerged.112 [Kunkel et al., 2008] Storm tracks have shifted northward over the last 50 years as evidenced by a decrease in the frequency of storms in mid-latitude areas of the Northern Hemisphere, while high-latitude activity has increased. There is also evidence of an increase in the intensity of storms in both the mid- and high-latitude areas of the Northern Hemisphere, with greater confidence in the increases occurring in high latitudes.112 [Kunkel et al., 2008] The northward shift is projected to continue, and strong cold season storms are likely to become stronger and more frequent, with greater wind speeds and more extreme wave heights.68 [Gutowski et al, 2008]

The northward shift in storm tracks is reflected in regional changes in the frequency of snowstorms. The South and lower Midwest saw reduced snowstorm frequency during the last century. In contrast, the Northeast and upper Midwest saw increases in snowstorms, although considerable decade-to-decade variations were present in all regions, influenced, for example, by the frequency of El Niño events.112 [Kunkel et al., 2008]

Then we have this apparently as yet unpublished research presented by Dr James Overland of the NOAA/Pacific Marine Environmental Laboratory at the recent International Polar Year Oslo Science Conference (IPY-OSC) where he was chairing “a session on polar climate feedbacks, amplification and teleconnections, including impacts on mid-latitudes.” “Cold and snowy winters will be the rule, rather than the exception,” says Dr James Overland…. Continued rapid loss of sea ice will be an important driver of major change in the world’s climate system in the years to come…. “While the emerging impact of greenhouse gases is an important factor in the changing Arctic, what was not fully recognised until now is that a combination of an unusual warm period due to natural variability, loss of sea ice reflectivity, ocean heat storage and changing wind patterns working together has disrupted the memory and stability of the Arctic climate system, resulting in greater ice loss than earlier climate models predicted,” says Dr Overland. “The exceptional cold and snowy winter of 2009-2010 in Europe, eastern Asia and eastern North America is connected to unique physical processes in the Arctic,” he says.

Even though these storms occurred during warmest winter on record, I think the best way to talk about it until Overland publishes his work is the way NCAR’s Kevin Trenberth did on NPR (audio here): RENEE MONTAGNE, host:  With snow blanketing much of the country, the topic of global warming has become the butt of jokes. Climate skeptics built an igloo in Washington, D.C. during last weeks storm and dedicated it to former Vice President Al Gore, who’s become the public face of climate change. There was also a YouTube video called “12 Inches of Global Warming” that showed snowplows driving through a blizzard.For scientists who study the climate, it’s all a bit much. As NPRs Christopher Joyce reports, they’re trying to dig out. CHRISTOPHER JOYCE: Snowed-in Washington is where much of the political debate over climate change happens. So it did not go unnoticed when a Washington think-tank that advocates climate action had to postpone a climate meeting last week because of inclement weather. That kind of irony isnt lost on climate scientists. Most don’t see a contradiction between a warming world and lots of snow. Heres Kevin Trenberth, a prominent climate scientist at the National Center for Atmospheric Research in Colorado. Mr. KEVIN TRENBERTH (Scientist, National Center for Atmospheric Research): The fact that the oceans are warmer now than they were, say, 30 years ago, means there’s about, on average, 4 percent more water vapor lurking around over the oceans than there was, say, in the 1970s. JOYCE: Warmer water means more water vapor rises up into the air. And what goes up, must come down. Mr. TRENBERTH: So one of the consequences of a warming ocean near a coastline like the East Coast and Washington, D.C., for instance, is that you can get dumped on with more snow, partly as a consequence of global warming. JOYCE: And Trenberth notes that you don’t need very cold temperatures to get big snow. In fact, when the mercury drops too low, it may be too cold to snow. There’s something else fiddling with the weather this year: a strong El Nino. That’s the weather pattern that, every few years, raises itself up out of the western Pacific Ocean and blows east to the Americas. It brings heavy rains and storms to California and the South and Southeast. It also pushes high-altitude jet streams farther south, which brings colder air with them. Trenberth also says El Nino can lock in weather patterns like a meteorological highway, so that storms keep coming down the same track. True, those storms have been big ones – record breakers. But meteorologist Jeff Masters, with the Web site Weather Underground, says it’s average temperatures — not snowfall — that really measure climate change. There’s more water vapor lurking around the oceans, and whatever the proximate cause of any one snow storm, there is little doubt that global warming means the overwhelming majority of East Coast storms will be sweeping in more moisture and dumping it on the ground.

“In Colorado, we get our wind from the west,” he explained. “Canada gets its wind from the east. Where the wind belts rub against each other – it causes friction. As friction occurs, it creates waves in the atmosphere. Waves create frontal systems. These frontal systems are most noticeable during the change of seasons, which is also when we get our biggest storms, particularly in spring and fall.” Fox concluded that climate change is tipping the balance toward a battle of heat and cold. “Storms, created when frontal systems collide, are the atmosphere’s way of dealing with differences in temperature,” he said. “The atmosphere is attempting to balance the energy and equalize the temperature with the air going from high pressure to low pressure.” Fox added that cold air is now coming further south than it used to and warm air is going further north than usual. “Wind is air trying to equalize pressure,” he said. The scientist then used the analogy of a runner eating a big bowl of pasta. “If he then downs a Red Bull, there is more energy in the system to fuel his run,” he said. This pasta analogy goes beyond the college classroom and has a practical and local effect as well. It can be applied to the recent wind and dust storms that have wreaked havoc on Durango locals and tourists alike. Bayfield motorcyclist Jeff Gilmore had his windshield sandblasted as he headed into Flagstaff recently. “Semis were lined up on the side of the road,” he said. “Foot high sand drifts progressed across I-89 from Page to Flagstaff.” Although he pulled down his full-face helmet and shut all the vents, Gilmore was still pounded. “Sand stuck to my chapstick and the fine grit got in my mouth,” he said.

Carlotta Haber and her daughter were sent 100 miles out of their way while driving from Durango to Sedona a few weeks ago. Just before Holbrook, Ariz., on I-40 West, a sign read, “Highway closed 43 miles ahead due to dust storm.” “I couldn’t see the car in front of me and big tumbleweeds were rolling at the car,” she said. These anecdotes are directly in line with scientific findings. In fact, the National Center for Atmospheric Research in Boulder has formulated global climate models forecasting that “all weather will get more extreme.” Storms are stronger than 20 years ago, according to NCAR, as the research center is predicting more precipitation per storm event, despite its forecast for fewer overall storms. Tim Foresman, former director of the United Nations Environmental program, explained, “These conditions are exactly what caused this past winter’s heavy snows in the East and the recent flooding in Tennessee. One was an extraordinary winter precipitation event and the other was a spring precipitation event.”

While these conditions may feel like an anomaly, research indicates that they are the logical result of changing conditions. National Climatic Data Center statistics reveal that in the last 30 years, the temperature has risen an average of 2 degrees in the United States. Since 1975, the average temperature in Colorado has increased by 2.28 degrees. The only two states whose temperatures have risen more are Utah, with a 2.43 degree increase, and Arizon,a with 2.79 degrees. A NASA report corroborates these findings. The report states that the last 12 months have been the warmest in at least 1,000 years. Foresman added, “The meteorological forecasts are based on prior weather patterns and may not be accurate without considering changes under way due to a warming climate. Forecasts are based on seasonal models from the immediate past and may not be a good indicator of the future due to changing climatic conditions.” His expertise has been extremely valuable to his sister-in-law, who just purchased property and is building a home in Durango. Counseling her on what to expect in the near future due to the changing patterns, she modified her construction plans.

Having recently experienced a blizzard in May in Santa Fe, Foresman stated the obvious. “The systems are all out of whack,” he said. “We’re going to be in for some interesting times. We can put our heads in the sand, or we can prepare.” In closing, Foresman remarked that the windiest days could be ahead for the Four Corners and Southwest and offered local residents a piece of advice. “If you have shutters on your windows, I suggest you make sure they’re functional and not decorative,” he said. “The winds aren’t going to go away until you turn the heat down.” •

The storms even afflict patrol officers. The DPS spent $3,800 on goggles for officers because of the stinging sand; some reported workplace injuries from irritated contact lenses, said DPS Sgt. Gary Phelps, who has patrolled northern Arizona for most of his 23-year career. "This is a new phenomenon. We have never had these conditions," Phelps said. "As far as visibility, this is the worst I've ever seen. I've been in blowing snow, but I'd take a snowstorm over a dust storm any day. It's awful."

Drivers must sit in 10-mile backups in both directions, the DPS and ADOT report. Many get frustrated and try to make sometimes dangerous U-turns across the freeway median. Some tourists rely on GPS systems to navigate detours. Often, they get stuck in the same brown cloud, lost on an unfamiliar rural road. Some dust storms can be 20 miles wide.

From 2000 through 2008, the state Department of Public Safety logged no dust-related collisions between Milepost 215, east of Flagstaff, and Milepost 260, just east of Winslow. Last year, Highway Patrol cars responded to 11 such accidents, and so far this year, five. Unlike the sudden, short dust storms that strike Interstate 10 south of the Valley, the recent I-40 closures typically last five hours and have dragged on for eight.

ADOT says that, before spring 2009, it had never closed I-40 because of dust storms. At the beginning of that particularly windy season, officials had to close the stretch of interstate between Flagstaff and Winslow because of a bad accident caused by blinding dust. That's when authorities began to close the highway as a precaution. They watched the weather forecast for high winds and sent spotters into the dust to gauge visibility.

From 1997 to 2008, the area recorded winds of more than 35 mph an average 12 times from March through May, Weather Service forecaster Ken Daniel said. Last year, that happened 14 times, and so far this year, 15 times. Winds above 45 mph had occurred an average 1.5 days during those spring months, but last year, they happened six times, and this year, four. "The springs of 2009 and 2010 have been windier than normal, but these winds we have been recently experiencing are not unprecedented," Daniel said.

Theories vary as to why the winds are thick with dust: Historical flooding of the nearby Little Colorado River left a lake bed that steadily dried out into fine sand. The nearby area has been overgrazed. A decade of drought has dried the soil into dust. "It could be global warming, for all I know," said Phelps, of the DPS.

ADOT says I-40 is the most heavily trucked highway in Arizona. Most are taking freight between Los Angeles and the Midwest. "Any time you have to disrupt the schedule of a delivery, it's not just a financial cost, it disrupts the entire supply chain," said Karen Rasmussen, president of the Arizona Trucking Association. "A truck has to arrive within a specific time slot for delivery." If the schedule is missed, manufacturers may have to shut down a plant because they don't have enough inventory. Grocers may not have enough produce, or perishables may start going bad. Trucks usually have return deliveries to make, and those get delayed. Northern Arizona's dust storms have become a national concern for the trucking industry, Rasmussen said.

While researchers are confident that the higher temperatures and resulting changes in snowpack, Colorado River flow, vegetation mortality and wildfires are human-caused, they don't know whether the drought that has plagued the West for the last 10 years – the worst since record-keeping began – is because of humans, Overpeck said.