Contributions of lake-effect period precipitation to the hydroclimate of the Great Salt Lake basin

This study examines the contribution of lake-effect precipitation to the coolseason (16 Sep - 15 May) hydroclimate of the Great Salt Lake basin. Lake-effect periods are identified based on the visual inspection of KMTX radar reflectivity imagery. Quantitative lake-effect period precipitation estimates are generated using high temporal resolution radar-derived precipitation estimates to disaggregate daily COOP and SNOTEL precipitation gauge observations. This preserves the daily precipitation gauge totals and enables the separation of accumulated precipitation into lake-effect and nonlake- effect periods. Evaluation of the method at two stations (Salt Lake City International Airport and Alta-Collins) demonstrates that the method works well for estimating climatological lake-effect period totals, with some random error in hourly estimates. Accumulated precipitation from 128 lake-effect periods indicates that Great Salt Lake-effect period precipitation contributes modestly (8.4% or less) to the cool-season precipitation of the Great Salt Lake basin with the largest contributions to the south and east of the Great Salt Lake. Lake-effect period contributions are highly variable from cool-season to cool-season and are dominated by intense episodic lake-effect periods. The most lake-effect period precipitation falls in the months of Oct and Nov. Lake-effect period precipitation also reaches a maximum when the 700-hPa wind is between 300-360°, corresponding to the longest fetch across the Great Salt Lake.