Contributions of Lake-Effect Periods to the Cool-Season Hydroclimate of the Great Salt Lake Basin

Abstract

Although smaller lakes are known to produce lake-effect precipitation, their influence on the precipitation climatology of lake-effect regions remains poorly documented. This study examines the contribution of lake-effect periods (LEPs) to the 1998–2009 cool-season (16 September–15 May) hydroclimate in the region surrounding the Great Salt Lake, a meso-β-scale hypersaline lake in northern Utah. LEPs are identified subjectively from radar imagery, with precipitation (snow water equivalent) quantified through the disaggregation of daily (i.e., 24 h) Cooperative Observer Program (COOP) and Snowpack Telemetry (SNOTEL) observations using radar-derived precipitation estimates. An evaluation at valley and mountain stations with reliable hourly precipitation gauge observations demonstrates that the disaggregation method works well for estimating precipitation during LEPs. During the study period, LEPs account for up to 8.4% of the total cool-season precipitation in the Great Salt Lake basin, with the largest contribution to the south and east of the Great Salt Lake. The mean monthly distribution of LEP precipitation is bimodal, with a primary maximum from October to November and a secondary maximum from March to April. LEP precipitation is highly variable between cool seasons and is strongly influenced by a small number of intense events. For example, at a lowland (mountain) station in the lake-effect-precipitation belt southeast of the Great Salt Lake, just 12 (13) events produce 50% of the LEP precipitation. Although these results suggest that LEPs contribute modestly to the hydroclimate of the Great Salt Lake basin, infrequent but intense events have a profound impact during some cool seasons.

Orographic Influences on a Great Salt Lake–Effect Snowstorm

“…These data reflect a precipitation-altitude relationship that has been frequently observed downstream of the GSL and other bodies of water (e.g., Hill 1971;Reinking et al 1993;Saito et al 1996;Steenburgh and Onton 2001;Onton and Steenburgh 2001;Steenburgh 2003;Yeager et al 2013). Potential contributors to the increase in precipitation with elevation include the following: 1) increased vertical motions forced by steep terrain, 2) subcloud evaporation and/or sublimation over adjacent lowland areas, 3) advection of slow-falling hydrometeors into downstream terrain, and 4) increased precipitation efficiency due to higher ice-nucleation rates when parcels are lifted to colder temperatures (e.g., Saito et al 1996).…”

“…GSL-effect events occur several times per year and impact transportation along a densely populated urban corridor (Carpenter 1993;Steenburgh et al 2000;Steenburgh 2003;Alcott et al 2012;Yeager et al 2013). They develop when a cold air mass moves over the relatively warm waters of the GSL, initiating or enhancing moist convection.…”

“…They develop when a cold air mass moves over the relatively warm waters of the GSL, initiating or enhancing moist convection. On average, periods with GSL effect (which is sometimes concurrent with precipitation generated by non-lake-effect processes) account for up to 8.4% of the total cool-season (16 September-15 May) precipitation [snow-water equivalent (SWE)] in areas south and east of the GSL (Yeager et al 2013). Most (all) of this precipitation falls as snow at valley (mountain) locations.…”

“…Most (all) of this precipitation falls as snow at valley (mountain) locations. Intense and long-duration events occur occasionally, including two during the 22-27 November 2001 ''Hundred-Inch Storm'' that together produced 107.4 mm of SWE at the Snowbird Snowpack Telemetry (SNOTEL) site in the Wasatch Mountains (Yeager et al 2013). …”

A Shallow Cumuliform Snowfall Census Using Spaceborne Radar

“…While ground-based observations of shallow snowfall are plentiful in certain locations like the Great Lakes region, shallow snowfall has also been documented in observational studies from other locations near large bodies of water such as the Great Salt Lake (e.g., Schultz 1999;Steenburgh et al 2000;Yeager et al 2013), the Sea of Japan-Okhotsk region (Katsumata et al 2000;Noh et al 2006), the Baltic Sea-Gulf of Finland region (e.g., Andersson and Nilsson 1990;Mazon et al 2015), and the Irish Sea (Norris et al 2013). Bech et al (2013) also studied a thundersnow event associated with relatively shallow cloud features in Spain near the Mediterranean Sea.…”