Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Lake-effect snow sometimes needs mountains

19.02.2013
Secrets of Utah's Great Salt Lake powder skiing machine

University of Utah researchers ran computer simulations to show that the snow-producing "lake effect" isn't always enough to cause heavy snowfall, but that mountains or other surrounding topography sometimes are necessary too.

The study is relevant not only to forecasting lake-effect storms near the Great Salt Lake, Sea of Japan, Black Sea and other mountainous regions, but also sheds light on how even gentle topography near the Great Lakes helps enhance lake-effect snowstorms, says the study's senior author, Jim Steenburgh, a professor of atmospheric sciences.

"It is going to help us with weather prediction – helping forecasters recognize that in some lake-effect events, the mountains or hills can play an important role in triggering lake-effect snow bands" over large bodies of water, Steenburgh says.

The new study was published today in the American Meteorological Society journal Monthly Weather Review. Steenburgh co-authored the study with first author and University of Utah Ph.D. student Trevor Alcott, now at the National Weather Service in Salt Lake City.

The research was funded by the National Science Foundation and the National Oceanic and Atmospheric Administration's National Weather Service.

Lake-effect snow's "negative impacts are in terms of snarling traffic and potentially closing schools," Steenburgh says, "And then there is the positive benefit for Utah skiers, which is a deep powder day that boosts our winter sports economy."

The lake effect occurs when a cold mass of air moves over a large body of warmer water, picking up moisture and heat to make the air mass rise and cool, ultimately dumping snow downwind. It already was known that lake-effect snowfall increases as the moist air rises over mountains. But the new study shows something new and different: mountains sometimes are essential to triggering the lake-effect over the lakes themselves.

"Most people recognize that mountains get more precipitation than lowlands because of moist air being lifted over the mountains," Steenburgh says. "Everybody recognizes that it plays a role in lake-effect storms. What we're showing here is a situation where the terrain is complicated – there are multiple mountain barriers, not just one, and they affect the air flow in a way that influences the development of the lake-effect storm over the lake and lowlands, rather than just over the mountains."

He says weather forecast models now fail to adequately include the Wasatch Range, which runs north-to-south directly east of the Great Salt Lake and the Ogden-Salt Lake City-Provo metropolitan area. Forecast models also don't include northern mountains along the Nevada-Idaho-Utah border, located northwest and north of the Great Salt Lake, Salt Lake metropolitan area and Wasatch Range.

"That may be one of the reasons we struggle" in forecasting lake-effect storms in Utah's major cities, Steenburgh says.

Indeed, the new study shows that without the northern mountains, more cold and moist air would flow south from Idaho's Snake River Plain, pass over Utah's Great Salt Lake and drop much more snow on the Salt Lake City area and Wasatch Range than real lake-effect storms.
How Mountains Can Contribute to the Lake Effect

The new study examined a moderate lake-effect snowstorm that hit metropolitan Salt Lake City and the Wasatch Range on Oct. 26-27, 2010. Some Salt Lake Valley cities had no snow, while others got up to 6 inches. The Alta Ski Area in the Wasatch Range got 13 inches of fresh snow, although it hadn't yet opened for the season.

The researchers found three key mountain-related or "orographic" factors were necessary to produce the October 2010 lake-effect storm, and that in this storm, the lake-effect occurred only because of the interaction between the Great Salt Lake and surrounding mountains:

Air moving over northern-northwestern Utah's mountains warms and dries as it flows downslope to the south and southeast toward the Great Salt Lake. Without this warming and drying, the lake-effect from the Great Salt Lake would be even stronger, the study found. This warm, dry downslope flow is similar to what are known as Chinook winds on the east slope of the Rocky Mountains or foehn winds flowing off the Alps.

The northern mountain ranges deflect the south- and southeast-flowing cold air masses so they converge over the Great Salt Lake. As the air picks up heat and moisture from the lake, it warms, making land breezes blow onto the lake from its western and eastern shores. The convergence of air from the north, east and west makes the air rise and cool, producing lake-effect snow bands over the lake.

The Wasatch and Oquirrh ranges, which respectively form the east and west boundaries of the Salt Lake Valley, act as a big funnel, forcing air flowing south off the Great Salt Lake to move directly into the valley, further enhancing air convergence and snowfall.

Simulating the Lake Effect

Since 1998, the Great Salt Lake has helped generate from three to 20 lake-effect snowstorms each winter, most of them relatively small and affecting some areas but not others. The average is about a dozen lake-effect storms each winter, Steenburgh says. Lake-effect storms account for about 5 percent to 8 percent of the precipitation south and east of the Great Salt Lake from mid-September to mid-May.

"There is a rich spectrum of lake-effect snowstorms," Steenburgh says. "Some cover a wide area with light snowfall. Some organize into more intense snow bands that produce heavier snow over a smaller area. Over the Great Salt Lake, 20 percent of our lake-effect events are these narrow intense bands."

The Oct. 26-27, 2010 weather event "wasn't a huge snowstorm," but fell between the two extremes, he adds.

An earlier study by Steenburgh showed that a Great Salt Lake-effect storm on Dec. 7, 1998 really was the result of the lake effect alone, like many storms from the Great Lakes. But the new study showed that during the lake-effect storm on Oct. 26-27, 2010, something quite different happened: Lake-effect snows fell only because of a synergistic interaction among the Great Salt Lake and mountains downstream.

Alcott and Steenburgh used weather data and existing weather research software to construct a "control" computer simulation that closely mimicked the real 2010 storm by incorporating the effects of the Great Salt Lake and surrounding mountains. Then they reran the simulation multiple times, but with various aspects missing.

"We can play God with this model," Steenburgh says. "We can see what happens if the upstream terrain wasn't there, if the lake wasn't there, if the Wasatch Range wasn't there."

The simulations showed that the lake effect would not have happened in the storm were it not for both the lake and downstream mountains:

A "flat, no-lake" simulation removed the lake and all mountains, as if all the landscape around Salt Lake City was flat and empty. The result was no snowfall.

The "no-lake" simulation removed the Great Salt Lake, but included all the surrounding mountains. This produced 90 percent less snow than the simulation of the real storm.

A "flat" simulation included the Great Salt Lake but no mountains. The result was 94 percent less snow than the simulated actual storm.

The "Wasatch only" simulation included the lake and Wasatch Range, but not the northern Utah mountains or the Oquirrh and Stansbury ranges west of the Salt Lake Valley. It produced 27 percent less snow than the simulation of the real storm.

A "downstream only" simulation, which included the lake and the Wasatch and Oquirrh ranges downstream from the lake, but not the upstream mountains in northern Utah. The result was 61 percent more snowfall than the simulated real storm because, without the northern mountains, more moist and cold air moves south from Idaho directly to the Great Salt Lake.

University of Utah Communications 201 Presidents Circle, Room 308 Salt Lake City, Utah 84112-9017 801-581-6773 fax: 801-585-3350 www.unews.utah.edu

Lee J. Siegel | EurekAlert!
Further information:
http://www.utah.edu

More articles from Studies and Analyses:

nachricht Multi-year study finds 'hotspots' of ammonia over world's major agricultural areas
17.03.2017 | University of Maryland

nachricht Diabetes Drug May Improve Bone Fat-induced Defects of Fracture Healing
17.03.2017 | Deutsches Institut für Ernährungsforschung Potsdam-Rehbrücke

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers shoot for success with simulations of laser pulse-material interactions

29.03.2017 | Materials Sciences

Igniting a solar flare in the corona with lower-atmosphere kindling

29.03.2017 | Physics and Astronomy

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

29.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>