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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Then we have this apparently as yet unpublished research presented by Dr James Overland of the NOAA/Pacific Marine Environmental Laboratory at the recent International Polar Year Oslo Science Conference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.

Hampton Roads in southeastern Virginia is unusually vulnerable. It is flat, and its land is sinking. It has nearly 2 million residents. It is home to popular beaches, waterfront homes, military bases, a huge tourism industry and ecologically valuable marshes.

"Hampton Roads is one of the most vulnerable regions in the United States to sea-level rise, in terms of population and assets at risk," said Eric J. Walberg, a former staff member for the Hampton Roads Planning District Commission.

Rising sea levels around the world are attributed to warming. When water warms, it expands. Melting polar ice sheets also raise the waters. In Virginia, sea levels are rising faster than the global average because the land is sinking

During the last ice age thousands of years ago, the weight of glaciers pushed down land in what is now the northern U.S. When those glaciers receded, that northern land began to rise, and land here started sinking, as if Virginia were on the end of a see-saw after the other rider got off. Throughout most of the 20th century, the sea level in southeastern Virginia rose about twelve-hundredths of an inch a year -- or 12 inches per century. But over the past two decades or so, the rate appears to have doubled in places. About half of that increase seems to be due to the sinking of land, and half to global warming, said Carl Hershner, a professor at the Virginia Institute of Marine Science. "And the forecast -- this is the scary part -- is for that acceleration to rise," Hershner said. Scientists say the future increases will be caused almost entirely by climate change. "We will still be sinking," Hershner said, "but that will be a smaller and smaller fraction of the change we experience."

Many of the piers at the Norfolk Naval Station were built around World War II. During storms or even higher-than-normal tides in recent years, the water began to rise so high that it flooded low-lying areas of the base and covered utility lines, including high-voltage electrical cables, suspended beneath the old piers. That meant frequent losses of power and other services to the base's ships. "Sea-level rise was having a negative impact on the readiness of the combat forces at the base," said Joe Bouchard, the base's commander from 2000 to 2003.

The Navy was already planning a multimillion-dollar project to replace the aging piers at Norfolk, the world's largest naval base. To cope with the rising waters, Navy engineers designed double-deck piers with the utility lines suspended from the main, upper deck, about 20 feet above sea level.

Cmdr. Wendy L. Snyder, a Defense Department spokeswoman, acknowledged that flooding occurs at the Norfolk and Langley bases. The department is concerned and is studying the problem, she said. "We are going to assess the impacts of climate change for all of our installations." As for possible base closings in Hampton Roads, Snyder said she did not want to speculate.

A powerful storm hit Virginia's coast in 1933. But the less-powerful Hurricane Isabel in 2003 -- which became a tropical storm about the time it entered Virginia -- caused similar flooding because the sea level by then had risen 9 to 10 inches. Isabel gained extra destructive power by sending its storm surge inland on higher waters, Hershner said. Isabel caused hundreds of millions of dollars in damage. On top of all that, scientists predict global warming will cause more-powerful storms in coming decades. And in Hampton Roads, more and more people are building near the shore, putting themselves and their property at risk.

Low-lying parts of Hampton Roads flood now from fairly routine storms and tides, said Skip Stiles, director of Wetlands Watch, a Norfolk environmental group. "Anywhere you go, people have stories" about how the water comes up higher than it used to.

SPC issued a "moderate risk" of severe storms and tornadoes a total of 5 times, in just 30 days. To put that in perspective between 2008 and early 2010 SPC had issued 5 moderate risks. So we endured (in one month) what had previously taken over 2 years to achieve in terms of elevated weather risk.

Soak up today's blue sky and 80-degree highs, because the latest NAM/WRF model (probably the most accurate & reliable simulation of future weather) is printing out nearly 4" of rain for the metro area Thursday. If that verifies it would be nearly a MONTH'S worth of rain in less than 12 hours.

Finally, the latest from NOAA: June was the warmest month, worldwide, since accurate records were first started in 1880. It was the 4th consecutive month of record warmth around the world, the 304 month in a row where global temperatures were above the 20th century average. 2010 is still on track to be the warmest year (globally) on record, even warmer than 2005. More coincidences? Possibly, but at some point you look at all these trends, scratch your head, and wonder if maybe those climate scientists aren't right (a recent poll of published, active PhD climate scientists showed that 97% of them believe the earth's atmosphere is warming, and man has at least some role in this warming trend). That's good enough for me - should be good enough for all of us mere mortals (who don't study the earth's climate 18 hours/day). The professional (paid) deniers and their "institutes" will come up with more excuses and refutations, citing a global conspiracy among climate scientists. Don't believe them, any more than you'd believe a tobacco lobbyist denying the ill effects of smoking and the link between tobacco and cancer. The trends are apparent to anyone taking the time to really look at the science. No one heat wave, month or year proves anything, but what we have here is a steady trickle of evidence, a gradual accumulation of coincidences that can no longer be denied. Melting glaciers, thinning arctic ice, rising sea levels, an uptick in drought and 1-in-500 year floods are all symptoms. The earth's atmosphere is running a mild fever. The question: do we believe the doctors and treat the patient now, or wait for those symptoms to worsen? It's not ideology, it's not a political litmus test, it's not a "new religion." It's basic science.

"There has not been a seasonal forecast of 23 storms put out for this country before," said Holland.  Like forecasters from NOAA and elsewhere (see More pre-season predictions of a very active Atlantic hurricane season, at the WunderBlog for a summary of forecasts), Holland cited high SSTs as a principal factor underlying his assessment. The SSTs during the first month of the hurricane season did nothing to diminish concerns.  As the figure below indicates, high SSTs characterized the tropical Atlantic in June, with many areas again seeing record high temperatures for the month. 

"So what’s happening?" asks Holland.  "Well it’s a combination of global warming and natural variability."

This is consistent with research results published in Geophysical Research Letters on 29 April 2010.  In Is the basin-wide warming in the North Atlantic Ocean related to atmospheric carbon dioxide and global warming?, Chunzai Wang and Shenfu Dong of NOAA's Atlantic Oceanographic and Meteorological Laboratory, conclude that "both global warming and AMO [Atlantic multidecadal oscillation] variability make a contribution to the recent basin-wide warming in the North Atlantic and their relative contribution is approximately equal."

There is agreement on one issue: excess greenhouse gases in the atmosphere will increase the intensity of storms (in general) and especially rainfall, since warmer conditions allow more water vapor to be sucked from the air. The higher risk of flooding is especially problematic for coastal areas because of storm surge. Researchers analyzing streamflows in large basins and GHG trends conclude that so-called 100-year floods likely will become more frequent.

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.

The havoc has brought total economic losses in the nine provinces to 14.5 billion yuan (€1.7 billion), and affected 535,500 hectares of crops, further blighting food supply in the region. The conditions have also led to the collapse of 68,000 houses.

The meteorological bureau was forecasting more thunderstorms overnight and it was expecting rainfall of 100-180 millimetres in many areas, rising to over 200 millimetres in others.

“The scope and intensity of the rain have increased,” the office said on its website yesterday.This is effectively three times the usual level of rain in the region.Climate change has meant that each year the flooding gets worse, while the droughts are also worsening.

Ms Lee Bee Wah, MP for Ang Mo Kio GRC and deputy chairman of the National Development and Environment Government Parliamentary Committees, said the flooding was a 'timely wake-up call' that something more needs to be done to prevent a similar occurrence.On Wednesday morning, 101 mm of rain fell over central Singapore in less than three hours. The average rainfall for the entire month of June is 162 mm.

Mr Cedric Foo, the chairman of the National Development and Environment GPCs, said he was concerned about the impact the flood would have on Singapore's image. He said: 'If such flash floods recur frequently, it will dent Singapore's standing as one of the world's most liveable cities.'

Mr Eugene Heng, the founder of Waterways Watch society, a volunteer group which helps clean up Singapore's canals and reservoirs, queried the practice of outsourcing critical maintenance work.

He added: 'I am surprised by the Orchard Road flooding. If we say our drainage system is good, then we should be prepared for unforeseen circumstances.'Historical rainfall data is not reliable, given the new circumstances caused by climate change.'