Wintertime Supercooled Liquid Water Flux over the Grand Mesa, Colorado

Authors

  • John R Thompson North American Weather Consultants Salt Lake City, UT
  • Arlin B Super Bureau of Reclamation Montrose, CO

Abstract

Supercooled liquid water (SLW) and wind measurements were made over the Grand Mesa of western Colorado during the period late January through March, 1986. Observations were obtained with an instrumented aircraft, a tower-mounted icing rate meter, and an acoustical sounder. These data were used to estimate the flux of SLW over the Mesa top, just upwind of the lee subsidence zone, during nine aircraft flights. The SLW flux calculations for a one meter width perpendicular to the wind ranged from 124 to 2707 g s^-1 with a median value of 600 g s^-1. These values compared favorably with previous flux calculations over the Mesa from microwave radiometer and tower wind measurements. Maximum possible precipitation rates were calculated from the flux estimates by assuming all available SLW was uniformly precipitated over 10 km. These precipitation rates varied from a low of 0.04 mm h^-1 to a high of 0.97 mm h^-1. Observed precipitation rates during the aircraft missions were in the same general range. However, marked variations occurred among storms in both observed and calculated precipitation rates which suggested that the natural precipitation efficiency of the sampled clouds varied widely. Several cases may have had significant cloud seeding potential.

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Scientific Papers