Denver Water and Winter Park Resort to pony up $110,000 for cloud-seeding

From the Sky-Hi Daily News (Tonya Bina):

[Winter Park] and Denver Water are sharing the $110,000 cost of the project, which will take place in locations within 35 miles of the ski area. Denver Water last partook in cloud seeding over Winter Park in 2002-2003 and 2003-2004. The project is slated to take place during the months of November, December and January, according to Steve Schmitzer, manager of water resource analysis for Denver Water.

Meanwhile, a supporting $60,000 cloud-seeding project will take place from November through March in the same area coordinated by the Colorado Water Conservation Board and water users from the lower Colorado River basin states of Arizona, California and Nevada…

About 10 Winter Park-Denver Water financed generators will be located on mostly private properties, and will be turned on and off depending on weather conditions and the presence of moisture-producing clouds. The two other generators will be located in higher areas and managed remotely by computer. The project involves a meteorologist who will determine appropriate times for cloud seeding. The quantities of iodide present in runoff due to cloud seeding equates to less iodine that what is found in salt on food, according to report on cloud seeding during the 2008 Arizona Weather Modification Conference. There is also more silver exposure found in tooth fillings, and there have been no human effects from cloud seeding found in 40 years of research, the report reads.

More cloud seeding coverage here and here.

Southwestern Colorado: Local cloud seeding projects

Here’s a background piece on cloud seeding in southwestern Colorado from Kristen Plank writing for the Cortez Journal. She has written a nice primer on the subject also. From the article:

[Larry] Hjermstad, founder of Western Weather Consultants LLC, seeds locally for approximately 10 different entities that support the cloud seeding program, from the town of Telluride to the Dolores Water Conservancy District.

The DWCD invests in two of Hjermstad’s cloud seeding programs in hopes to increase inflow into McPhee Reservoir. Mike Preston, manager for the DWCD, said the water district has played a part in the program since 2000, and paid approximately $17,000 for the 2008-2009 winter program. “Ski areas are investing in the program for the snow to ski on, but our interest is pure and simple,” Preston said. “If we can increase the inflows into the McPhee Reservoir by some percentage, then everyone benefits.”[...]

Hjermstad recounted an independent study done by Bernard Silverman, prior chief scientist with the U.S. Bureau of Reclamation, that showed the effects of a 33-year cloud seeding program on Vail’s surrounding streams. The study, lasting from 1977 to 2005, showed an eight to 30 percent increase in stream flows. “(Silverman) wasn’t looking at snow as being of value, but rather water as being of value,” Hjermstad said. “The study verified that precipitation increases are reflected in stream flow increases. To me, this is the missing ‘ground link’ for what we are trying to do with precipitation.”[...]

Cloud seeding, or weather modification practices, is a popular process throughout the world. Locally, a total of 34 “ice nuclei” generators are spread across the San Juan Mountains, working from November through the end of March. Hjermstad will have operators turn on generators for roughly 24 storms during a three-month period.

Well over a trillion seemingly invisible silver iodide nuclei will work their way into the bottom portion of a cloud system, where they will attract moisture, produce snowflakes and fall to earth. The compound works so well at producing additional snowfall because of its nearly identical characteristics to an ice crystal. It’s as safe as one, too, Hjermstad said. “One reason silver iodide was chosen was because, as a molecule, it is extremely tightly held together once the two elements combine,” he said. “Nothing in nature breaks it apart.” This includes the sun, the photosynthetic process in plants, or anything from the digestive systems of humans, animals or aquatic wildlife. Hjermstad said that cloud seeding programs also do not take away from any precipitation that may have been dispersed into towns downwind.

More Coyote Gulch coverage here and here.

Four years of Wyoming cloud-seeding efforts

Here’s an update on Wyoming’s 5 year cloud-seeding project, from Wes Smalling writing for the Casper Star Tribune. From the article:

[Bruce] Boe is one of several scientists working on the five-year Wyoming Weather Modification Pilot Project, an $8.8 million research program funded by the state of Wyoming. The project’s scientists, along with state water managers, hope to find proof of whether the decades-old practice of seeding clouds — trying to squeeze more precipitation out of passing storms — actually works and that it’s a practical option for increasing the state’s water supply. Members of the world’s science community — cloud-seeing advocates and skeptics alike — are watching the project closely. “For a scientist doing research, this is it. As far as in terms of the research, it is the biggest in the United States by far,” Boe said…

The Wyoming project is in its fourth year, only the second winter in which cloud seeding in earnest has actually been performed. The first two years involved mostly taking measurements and weather readings, obtaining permits from the U.S. Forest Service, gathering other statistical data and getting equipment in place…

While Boe’s company is contracted to perform the cloud-seeding operations, independent teams of scientists from the Colorado-based National Center for Atmospheric Research and the Desert Research Institute in Nevada are independently evaluating whether any increases in precipitation that occur are from cloud seeding or from just normal variations in the weather. That’s the real trick to proving if it works. Cloud-seeding scientists estimate that, if done properly, pumping silver iodide into a cloud will increase snowfall in most cases by about 10 to 15 percent. That’s roughly the same percentage of natural variability possible in normal weather patterns…

It’s too early to say with any certainty that Wyoming’s cloud seeding is working to make more snow, but the scientists are beginning to amass a massive amount of vital information from the project. They still have much more data to collect. They conducted 26 four-hour seeding events in southern Wyoming last winter and more than 30 this winter. Ideally, they would like to have more than 200 cases to examine by the end of the five-year project…

While clouds are often seeded from airplanes, the seeding on the Wyoming project this winter is all being done from the ground by generators on 20-foot towers. Inside a generator placed upwind, a propane flame heats the silver iodide solution, and a nozzle sprays it into the air. It rises into the cloud and is carried by the wind to a target area, which is where the scientists want it to snow. There are eight generators in each mountain range, the Snowies and the Medicine Bows, and another seeding site on the west side of the Wind River Range that has 10 generators.

Meteorologists determine when conditions are right for seeding and tell the technicians which generators to turn on. The technicians, sitting many miles away at computers, activate the generators remotely through satellite modems. Boe, using a machine in his cabin called an acoustic ice nucleus counter, checks the outside air during seeding operations to detect the presence of silver iodide to make sure the particles are reaching the target area…

Before, during and after seeding events, the weather is monitored closely. Independent evaluation teams from NCAR and DRI check the snow for the presence of silver iodide and to collect other statistical data. Seed generators are never turned on at the same time in both the Snowy Range and Medicine Bow Mountains — only randomly either in one mountain range or the other. The forecasters and evaluators are not told which mountain range was seeded, which should eliminate any bias in their predictions and conclusions, said Dan Breed, lead scientist for NCAR. Seeding only one range at a time also allows researchers to collect a double dose of data from each storm — one from a seeded mountain range and one that only received natural snowfall. Comparing results between the two ranges could help determine if increases in snow were a result of seeding or that ever-elusive variability that occurs with natural snowfall…

Periodically this winter, [University of Wyoming] professor Bart Geerts and graduate students will fly over snowstorms in a Kingair research aircraft as cloud-seeding experiments are going on to study how the clouds are affected. Using technologies called cloud radar and LINAR, short for Light Detection and Ranging, the crew will take snapshots of the clouds similar to the three-dimensional slices of a medical MRI scan. “We are basically trying to look at it in the finest detail in time and space. We’re actually looking at the cloud as it is injected with silver iodide,” Geerts said. When a cloud is seeded, “The idea is that silver iodide injected into a cloud is going to turn all that liquid water into ice pretty quickly. We want to see if that really happens.”[...]

University of Tennessee professor Glen Tootle is leading a study on the effects of an increased snowpack on spring and summer runoff. The university experiment could determine what a small snowpack increase in the Medicine Bow Mountains would mean for the North Platte River drainage. No one knows for sure if 10 percent more snow created from cloud seeding would necessarily produce 10 percent more water for the state’s supply. “Those basic questions have not been answered,” Geerts said.

More Coyote Gulch coverage here.