Cloud-seeding gaining favor in arid West — The Durango Herald

From the Cortez Journal (Jim Mimiaga) via The Durango Herald:

Telluride and Purgatory ski areas contribute funds for regional cloud-seeding programs, and so do the Dolores Water Conservation District, Animas-La Plata and Southwestern Water Conservancy districts.

During a meeting Wednesday at the DWCD office in Cortez, an update was given on the regional cloud-seeding program and ground-breaking research recently completed on the technology in Wyoming.

“Interest in cloud seeding has grown, and funding has grown,” said Bruce Whitehead, executive director for SWCD.

Western Weather Consultants provides cloud-seeding services for three programs in the San Juan Mountains including over the Upper Dolores, La Plata, and Animas River basins.

From November 2014 to April 2015, 25 cloud-ice nuclei generators dispersed silver iodide into storm clouds for a total of 875 hours, at a cost of $105,678.

The units are in the vicinity of Cortez, Dolores, Mancos, Mesa Verde, La Plata Mountains, Stoner, West Fork, Groundhog, House Creek, Placerville, Cahone, Lone Cone, Disappointment, Hesperus, Electra Lake, Bayfield, near Purgatory, on the Florida River and elsewhere.

When dispersed in optimum storm conditions, the silver iodide enhances the formation of ice crystals in clouds, forcing more snowfall, said Mike Hjermstad, a technician with Western Weather Consultants, based in Durango.

“The generators are turned on manually, and when the conditions are right, it can increase snow accumulation from a storm by a half inch,” he said…

Cloud-seeding skeptics question whether the procedure actually works because it’s difficult to verify increased snowfall from cloud seeding versus what would fall naturally.

Proponents point to experiments that show areas with cloud seeding had more precipitation compared with control areas that did not get the treatment.

“Detection of very minute levels of silver iodide in the snowpack is also a proof,” Hjermstad said.

Joe Busto, a cloud-seeding permit manager for the Colorado Water Conservation Board, said the environmental impacts of the silver iodide on snowpack is “very low and measured in parts per trillion above background levels.”

He said research shows “strong suggestions of positive cloud seeding effects in winter glaciogenic systems occurring over mountainous terrain.”

Rising costs of new technology such as radiometers, automation, and more snotels is a concern, said Ken Curtis, an engineer for DWCD.

“The funders need to have consensus on where the program is going, if it will be enhanced or stay static,” he said.

Barry Lawrence, of the Wyoming Water Development Office, gave a presentation on a recent groundbreaking cloud-seeding study that showed good results.

The 10-year study cost $15 million and was funded by the Wyoming Legislature.

The elaborate experiment positioned remote-control seeding stations in the Wind River Range and in the Medicine Bow Range.

When winter storm conditions were ideal for seeding in both ranges, only the stations in one range were triggered on. The range without cloud seeding was the control, and then snowpack from both ranges was compared for that storm. Control ranges were alternated throughout the experiment.

Despite some cross contamination in the controls, additional modeling and statistical analyses showed cloud-seeded ranges overall benefited from additional snowfall, Lawrence said.

“Our independent evaluator, the National Center for Atmospheric Science in Boulder, concluded cloud seeding from the experiment resulted in 5 to 15 percent in additional precipitation,” he said.

Encouraged by the results, the Wyoming Legislature recently approved $1.5 million to install operational cloud-seeding stations in the Medicine Bow Mountains and other ranges.

More cloud seeding coverage here.

Can cloud-seeding ride to the rescue? — The Mountain Town News #ColoradoRiver

lowlakemead2012allenbest

From The Mountain Town News (Allen Best):

After a so-so winter, the snow piled up through May in the mountains of Colorado, taking the edge off drought. This takes the edge off of the big Colorado River reservoirs, Lake Mead and Lake Powell. But the overarching story at those reservoirs since 1999 has been of decline, even after a few big years.

In the last several years, there has been increasing talk about the potential for the two reservoirs to become empty. Las Vegas, reliant upon Lake Mead for most of its water, isn’t just talking about the possibility. It is nigh-on to completing a third tunnel into the reservoir, this one at a cost of $817 million and, unlike the others, at the very bottom of the reservoir, in case there’s nothing left of Lake Mead except for the Colorado River. That’s how dire Las Vegas, operating as the Southern Nevada Water Authority, takes this potential of long-term drought.

Eric Kuhn, the manager of the Colorado River Water Conservation District, spoke to the implications of this continuing drought at a forum in Colorado’s Summit County this spring. “Bad things happen when Lake Mead and Lake Powell get drained,” he said in an event covered by the Summit Daily News. He described the draining of Lake Mead as a distinct possibility in the next few years.

What about building a pipeline to the Mississippi River or some other water-rich location? “To expect that we can export our problems to somebody else, I just don’t see that somebody else will willingly accept them,” he said.

How about just making some more water? That effort began soon after World War II in different times of drought. Scientists at General Electric in New York state had discovered the general principle. And in some places of the West, cloud-seeding has occurred since the 1950s – including, at Vail Mountain, since 1978.

But does it work? Since the federal government yanked research dollars from cloud-seeding experiments in the 1980s, relatively little rigorous science had been conducted. Instead, there were the claims of commercial-cloud seeders, who predicted gains of 10 to 15 percent—as long as they had clouds to work with.

In 2004, Wyoming set out to fill that gap. An experiment that ultimately cost $14 million was designed by scientists working for a federal laboratory, the National Center for Atmospheric Research. Parallel mountain ranges southwest of Laramie, just north of the Colorado border, constituted the Wyoming laboratory. Propane was burned to loft silver iodide from ground-based generators into the clouds passing over the Sierra Nevada and Medicine Bow ranges. In the experiment, 154 storms during six winters had the temperatures needed for effective seeding, but only 118 had the moisture content. And of those, 18 were tossed out because of contamination problems.

Slim statistical evidence

Last December, at a meeting room in Cheyenne, scientists delivered the results. It took a full afternoon and the results were sometimes confusing. But hydrologists and meteorologists who listened to the proceedings remotely told me they had no trouble hearing the key statistics: just a 3 percent increase in precipitation but with the 28 percent probability that cloud-seeding had nothing to do with the increase. Only by creating models were researchers able to make a case that snowfall had been augmented 5 to 15 percent.

instumentationcloudseedingresearchcolorado

Taking stock of this and other winter weather-modification studies, the Bureau of Reclamation was unimpressed. “As such,” said the agency in a draft analysis released in February, “the ‘proof’ the scientific community has been seeking for many decades is still not in hand.”

Proof in science requires a 95 percent probability of causality. This is extremely difficult to achieve in complex atmospheric processes, whether cloud-seeding or many of the processes involved with a warming global climate.

In Wyoming, elected officials have decided the evidence to support cloud-seeding is strong enough to justify additional investments in various drainages—including the Wind River Range, which produces water for a tributary of the Colorado River—even as they have been loathe to admit the science of global warming.

Wyoming isn’t alone. Water agencies and cities from Denver to Los Angeles pay for seeding clouds in the mountains of Colorado and Wyoming, and representatives heard what they wanted to hear.

“It’s good evidence that it works,” said David Cole, who administers weather-modification programs for the Utah Division of Water Resources.

“There is always that question, ‘Can you prove it beyond a shadow of a doubt?’” he added.

From Los Angeles comes a similar appraisal of confirmation. “These results are consistent with historic studies,” said Tom Ryan, of Metropolitan Water District of Southern California, a consortium of agencies that collectively serves 18 million people.

I heard similar remarks from the Central Arizona Project, which uses a 336-mile-long system of aqueducts, tunnels, pumping plants, and pipelines to deliver water to Phoenix, Tucson, and cotton farms and golf courses along the way.

Along with Las Vegas, Arizona and California chip in to pay for cloud-seeding in Colorado and Wyoming.

Dan Breed, project scientist with NCAR, said that failing to achieve a 95 percent confidence level in results is not unusual in cloud-seeding studies. The fundamental problem, he says, is the complexity of atmospheric processes.

It’s the same challenge that has prevented most climate scientists from linking specific weather events, such as the September 2013 floods in Colorado, to rising global temperatures and the 3 to 5 percent observed increase in atmospheric moisture related to that warming.

“When it comes to the atmosphere, there are just too many variables, and that variability just keeps rearing its ugly head when it comes to cloud-seeding,” says Breed. “Even in this case, where we tried to make things as homogeneous as possible to reduce that variability, variability still kind of hurt us.”

Breed thinks research might better be invested in understanding specific atmospheric processes of wind, temperature, and precipitation. For example, how likely is it that silver iodide or other seeding agents released from the ground will get into the clouds?

Understandings of atmospheric processes, says Breed, has mostly come from observations, instead of experiments – because of that same variability.

This lack of certainty does not necessarily kill the prospects of cloud-seeding, as is demonstrated by the continued interest of Wyoming legislators in funding cloud-seeding.

Cloud-seeding to the rescue?

Can cloud-seeding the answer to the problems of California, now in its fourth year of drought, or of the Colorado River?

The river is notoriously strapped to meet all of the wants and maybe even the needs. River flows have declined 20 percent in the 21st century as compared to the last century.

Breed disputes conclusions that cloud-seeding doesn’t necessarily work. But he doesn’t see it as a game-changer for the Colorado River. Modifying the weather is a fairly straightforward, quick and inexpensive way to produce more water, but the gains are marginal. “It is not, he says, a magic bullet. “It won’t solve the problem.”

In his appearance in Summit County, Kuhn took a broad view, describing the 21st century as a time of transition. “After 100 years of develop more, develop more, develop more, we’re going to have to cut back our uses.”

That’s the difficult conversation now underway in California as residents in places like San Jose argue about lawn sizes and almond groves. It’s also the more earnest conversation that, despite the extraordinary rains in May, is getting underway in Colorado.

More cloud seeding coverage here.

Wyoming’s 10 year cloud-seeding experiment scrutinized

Cloud-seeding graphic via Science Matters
Cloud-seeding graphic via Science Matters

From the East Oregonian (Allen Best):

Wyoming just spent $14 million and the better part of 10 years on a rigorous scientific experiment to evaluate whether it’s possible to get extra snow from winter storm clouds through cloud seeding. The conclusion? The final results were thin: There was a 3 percent increase in precipitation, but a 28 percent probability that the cloud seeding had nothing to do with it.

Given the results of this and other winter weather-modification studies, the Bureau of Reclamation remains unimpressed. “As such,” said the agency in a draft analysis released in February, “the ‘proof’ the scientific community has been seeking for many decades is still not in hand.”

Proof in science requires a 95 percent probability of causality. But this standard is extremely difficult to achieve in complex atmospheric processes. Climate scientists, for example, mostly resort to asterisk-laden words such as “likely” to indicate lower levels of probability…

From the start, Wyoming’s cloud-seeding experiment was designed to ensure scientific rigor. Parallel mountain ranges southwest of Laramie, just north of the Colorado border, constituted the Wyoming laboratory. Propane was burned to loft silver iodide from ground-based generators into the clouds passing over the Sierra Nevada and Medicine Bow ranges. In the experiment, 154 storms during six winters had the temperatures needed for effective seeding, but only 118 developed adequate moisture content. And of those, 18 were tossed out because of contamination problems.

Dan Breed, project scientist with the National Center for Atmospheric Research, which designed and oversaw the Wyoming experiment, said that failing to achieve a 95 percent confidence level in results is not unusual in cloud seeding studies. The fundamental problem, he says, involves the difficulty of measuring atmospheric processes.

The challenge inherent in the complexity of the data has prevented most climate scientists from directly linking specific weather events, such as the September 2013 floods in Colorado, to rising global temperatures, or even to the 3 to 5 percent observed moisture in the global atmosphere.

“When it comes to the atmosphere, there are just too many variables, and that variability just keeps rearing its ugly head when it comes to cloud seeding,” says Breed. “Even in this case, where we tried to make things as homogeneous as possible to reduce that variability, variability still kind of hurt us.”

Breed thinks research might better be invested in understanding the interaction in the atmosphere of wind, temperature and precipitation. For example, how likely is it that silver iodide or other seeding agents released from the ground will get into the clouds? True understanding of atmospheric processes, says Breed, has mostly come from observations instead of experiments — because of that same variability.

This lack of certainty does not necessarily kill the prospects of cloud seeding, as is demonstrated by the continued interest of Wyoming legislators in funding projects. In the Colorado River Basin, cities and water districts seized upon the modeled projections of 5 to 15 percent snowpack augmentation as justification for continued or even expanded operations. Already, metropolitan Los Angeles, the Central Arizona Project and the Southern Nevada Water Authority, among others, pay for seeding clouds in Colorado, the source of half the water in the Colorado River, and last year they also paid to seed clouds in Wyoming, in the Green River drainage.

More cloud seeding coverage here.

Wyoming reconsiders cloud seeding and potential benefits for ag

More cloud seeding coverage here.

Cloud seeding study boosts hopes in parched West — WyoFile

Cloud-seeding graphic via Science Matters
Cloud-seeding graphic via Science Matters

From Environment & Energy Daily (Annie Snider) via WyoFile:

As a painful reckoning sets in throughout the West, where the Colorado River Basin is in its 15th straight year of drought, desperate water managers are welcoming a new cloud-seeding study as rare good news.

The concept of cloud seeding — using aircraft or ground-based generators to inject microscopic particles of silver iodide into clouds around which ice crystals can form and fall as snow — dates back to the 1940s.

Today, ski resorts, water districts and farmers across the West swear by the practice to produce both snow and water, spending millions of dollars a year on machines and flights.

But proving that money is well-spent has been tricky. Because, while it might snow or rain after a cloud’s been seeded, it’s hard to know whether the seeding actually caused the precipitation…

Wyoming’s Legislature took the challenge and, buoyed by coffers filled from oil and gas severance taxes, poured $14 million into a major study over the past 10 years that employs the latest scientific techniques recommended by the NRC panel, as well as an independent evaluation team.

The topline findings, recently unveiled to the Legislature: Seeding the right storms the right way can produce 5 to 15 percent more precipitation. That could increase streamflows by as much as 3.7 percent, the researchers’ initial findings indicate.

The study also found seeding to have next to no downwind impact, suggesting seeding storms to get precipitation in one place is not decreasing precipitation elsewhere.

“We know that silver iodide produces ice crystals, so really it ends up being an engineering problem: Can the ice crystals get into the right cloud at the right place and can we do all this?” said Roy Rasmussen, a senior scientist with the National Center for Atmospheric Research who led the study’s outside evaluation team.

“That’s what the Wyoming program demonstrated: That, yes, they can do it,” he said. “With modern technologies — through satellite-controlled silver iodide generators, and with good forecasting, with good real-time modeling — we can figure out when the storms are right for seeding and apply the seeding, and there is a measurable effect.”

More cloud seeding coverage here.

Water Lines: Cloud seeding can work, but it won’t fill Lake Powell — Grand Junction Free Press

Cloud-seeding graphic via Science Matters
Cloud-seeding graphic via Science Matters

From the Grand Junction Free Press (Hannah Holm):

In the arid West, the perpetual search for new water supplies, like the mythical search for the Holy Grail, has given rise to numerous fantastical adventures and grand schemes. Some of these have resulted in the impressive feats of engineering that have re-plumbed much of the Colorado River Basin, and some have remained fantasies, like towing ice bergs from the Arctic and building pipelines from the Great Lakes.

“Cloud seeding” to wring more moisture from the sky has long been hard to classify in those terms. Water agencies and ski resorts have been doing it for decades, mostly by sending plumes of silver iodide from ground-based burners into likely-looking clouds. Cloud seeding has been done in Colorado since the 1950s and ramped up significantly after the 2002 drought. Still, until recently, no one could say with any certainty if cloud seeding really worked, or if so how well.

Draft conclusions from a much-anticipated, very rigorous nine-year study conducted in Wyoming indicate that cloud seeding can, in fact, increase the water yield from some storms, but the ultimate effect on the water supply is quite modest. The draft executive summary of the Wyoming Weather Modification Pilot Program study, conducted by numerous collaborators, was presented to the Wyoming Water Development Commission on Dec. 10; it is due to be finalized in March of 2015.

The study combined physical, modeling and statistical studies of the effects of cloud seeding in Wyoming’s Medicine Bow, Sierra Madre and Wind River Ranges and concluded that seeding could increase snow accumulations from some storms by 5-15 percent. This does not, however, translate to a 5-15 percent increase in the seasonal snowpack because not all storms are “seedable,” and those that are cover only a limited area.

In order for the inserted silver iodide to stimulate significant additional snowfall, atmospheric temperatures must be below 17 degrees Fahrenheit, with sufficient moisture in the air and favorable winds. These conditions were met less than one-third of the time during the winter in the study area. Using modeling, the study concluded that increased precipitation from seeded storms of 5-15 percent affecting 30-80 percent of the cloud-seeding impact area could increase streamflow in Wyoming’s portion of the North Platte River Basin between 0.4 to 3.7 percent.

Depending on numerous factors related to the operations of the cloud seeding program, the cost-per-acre-foot of water produced through cloud seeding ranges from $27-$427 per acre-foot. This compares favorably with other options for producing “new water.” In a 2013 article in the Mountain Town News, Allen Best reports that the Bureau of Reclamation has estimated that desalting brackish groundwater in Arizona would cost $650 per acre-foot, and desalting ocean water near Los Angeles would cost $2,100 per acre-foot. Cost estimates for building new storage reservoirs run from a few hundred dollars per acre-foot to over $1,000 per acre-foot.

In addition to assessing the potential impact of cloud seeding as a feasible strategy for impacting Wyoming water supplies, the study also assessed the environmental impacts of seeding and impacts on precipitation outside the seeded area (i.e. does it steal water from downwinders?).

The environmental analysis found that concentrations of silver iodide in the affected snowpack was in the parts per trillion range, while concentrations already in the soil were much higher, in the parts per billion range, indicating a very minimal impact from cloud seeding. Modeling of impacts on precipitation outside the seeded area indicated effects of less than 0.5 percent, which is consistent with previous studies and undermines claims that cloud seeding injures those downwind of seeded areas.

This study indicates that cloud seeding likely deserves its relatively newfound respectability as a water supply strategy, but also that its impacts are far too small for it to be a panacea for the West’s water woes.

To read the draft executive summary for yourself, go to the Wyoming Water Development Commission’s website at http://wwdc.state.wy.us.

More cloud seeding coverage here.

Report: Wyoming cloud seeding program said to increase snowpack

wyomingweathermodificationpilotprogramexecsummaryfinaldraft12102014

Click here to read the draft executive summary. Here’s an excerpt:

The Wyoming Weather Modification Pilot Program (WWMPP) was conducted to assess the feasibility of increasing Wyoming water supplies through winter orographic cloud seeding. Following a Level II feasibility study that found considerable potential for cloud seeding in the state (WMI 2005), the Wyoming Water Development Commission (WWDC) funded the WWMPP (2005-2014) as a research project to determine whether seeding in Wyoming is a viable technology to augment existing water supplies, and if so, by how much, and at what cost. The WWMPP then established orographic cloud- seeding research programs in three Wyoming mountain ranges considered to have significant potential: the Medicine Bow, Sierra Madre, and Wind River Ranges…

Orographic cloud seeding is a technology designed to enhance precipitation in winter storms with an inefficient precipitation process due to a lack of natural ice nuclei. This inefficiency allows supercooled water to persist for long periods instead of being depleted by ice crystals, which grow and fall as snow. This fact is well documented by the measurement of sustained supercooled liquid water in orographic clouds taken by aircraft and ground-based instruments, such as radiometers. In contrast to natural ice nuclei, artificial ice nuclei, such as silver iodide, will nucleate substantial numbers of ice crystals at subfreezing temperatures of −8 °C (+17 °F) and cooler, creating ice crystals in clouds that are typically too warm for natural ice formation. In the presence of supercooled water droplets, these ice crystals rapidly grow into larger particles that fall to the ground as snow. The technology of orographic cloud seeding uses ground-based generators to produce a silver iodide plume, which is then transported by the ambient wind into orographic clouds to increase precipitation. This process of seeding clouds to create additional snow is complex and to date has not been scientifically verified in well-designed statistical tests.

More cloud seeding coverage here.