Sunday, February 8, 2015

Lake Effect Weather

The Great Salt Lake has some influence on the local weather climate of its surrounding communities. The high salt content in the water of the lake (which averages 15% on the south arm and 25% on the north arm of the lake, compared to 3½% for the world's oceans) prevents most of the lake's surface from freezing during the winter months. This open water naturally adds moisture to the air flowing over the lake, enhancing precipitation along the Wasatch Mountains and producing heavy "lake effect" snowstorms.
"Lake effect" snowstorms generally occur five to six times a year during the fall and spring months. Such snowstorms usually develop when a cold northwest storm moves over the warmer Great Salt Lake. The warm, moist lake air then rises into the cold air above, causing dense clouds to form. The clouds then drop heavy snow downwind from the lake. The strongest "lake effect" storms appear to happen when there is a 10-15 degree F., temperature difference between the waters of the Great Salt Lake and the air flowing over it. On October 18, 1984, a "lake effect" snowstorm dropped up to 18 to 24 inches of snow on the east benches of the Salt Lake Valley, causing over $1,000,000 worth of damage to utility lines, homes, businesses and cars.
In addition, the large surface area of the Great Salt Lake is responsible for an average daytime "sea breeze" of eight to 12 miles per hour over nearby valleys. This breeze often lowers afternoon temperatures in areas near the lake by as much as two to four degrees F., during late spring and early summer.
"Lake Stink"
Occasionally it is possible to smell foul odors that originate from the Great Salt Lake. These odors can be smelled in populated areas located several miles or farther from the shore of the lake.
Winds associated with a cold front (moving northwest to southeast over the lake) often churn up the water in the Great Salt Lake and encourage the release of bacterial odor from decomposing aquatic vegetation, brine shrimp and flies. The winds then carry this odor downwind to populated areas. These pronounced odors are usually detected during the fall months, although the odor also occurs during the summer season.
On October 24, 1983, Wasatch Front residents described the day as one of the worst "lake stink" days they had ever experienced in Salt Lake and Davis Counties. Brisk northerly winds in the wake of a cold front stirred up the rotting aquatic marsh vegetation in the lake, and the combination of a high lake level and low salinity resulted in an above normal amount of vegetation available for decay around the lake. Also, the decomposition of brine shrimp and flies added to the smell. The "stink" was detected by people as far south as Juab County.
For more information on the above subjects visit:
Utah Geological Survey - Great Salt Lake
Much of the information for this section originally appeared in the copyrighted book Utah's Weather and Climate, edited by Dan Pope and Clayton Brough, in 1996. UCCW Directors have received permission from the copyright owners of this book to reproduce such information on its website and to revise and updated it where appropriate.

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