Synoptic Climatology of Significant Fog Events at Truckee, California

Brian F. O'Hara
National Weather Service
Weather Forecast Office
Reno, Nevada

ABSTRACT

     A climatology of significant fog events (visibility dropping to 0.5 statute mile or lower for at least six consecutive hours) for the Truckee-Tahoe Airport (KTRK) in Truckee, California, is presented. The climatology is based on surface observation data from July 1994 through June 2009. National Centers for Environmental Prediction (NCEP) reanalysis data are used to determine which upper air patterns are favorable for periods of significant fog formation. These patterns are: (a) a building ridge after an upper low/trough passage, (b) an upper low/trough offshore/approaching from the west, and (c) an upper trough over the region. Periods of significant fog are most frequently observed at night during the winter months at Truckee.



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