Lake-Breeze Fronts in the Salt Lake Valley

Abstract

Winds at the Salt Lake City International Airport (SLC) during the April?October period from 1948 to 2003 have been observed to shift to the north (up-valley direction) between late morning and afternoon on over 70% of the days without precipitation. Lake-breeze fronts that develop as a result of the differential heating between the air over the nearby Great Salt Lake and that over the lake?s surroundings are observed at SLC only a few times each month. Fewer lake-breeze fronts are observed during late July?early September than before or after that period. Interannual fluctuations in the areal extent of the shallow Great Salt Lake contribute to year-to-year variations in the number of lake-breeze frontal passages at SLC. Data collected during the Vertical Transport and Mixing Experiment (VTMX) of October 2000 are used to examine the structure and evolution of a lake-breeze front that moved through the Salt Lake Valley on 17 October. The onset of upslope and up-valley winds occurred within the valley prior to the passage of the lake-breeze front. The lake-breeze front moved at roughly 3 m s?1 up the valley and was characterized near the surface by an abrupt increase in wind speed and dewpoint temperature over a distance of 3?4 km. Rapid vertical mixing of aerosols at the top of the 600?800-m-deep boundary layer was evident as the front passed.