WMOD00475

• Title: The Characteristics and Evolution of Supercooled Water in Wintertime Storms Over the Sierra Nevada: A Summary of Radiometric Measurements taken During the Sierra Navada Cooperative Pilot Project
• Date: 7/1/1987
• Weather Modification - Doc Type: Report

level. Precipitation amounts were gre~ter than in storms with onshore or inland

trajectories. Strong convection often occurred west of the project area. Winds

over .the Sierra Nevada were weak at all levels, since the project area was

within the long wave trough.'

4. CASE STUDIES OF LIQUID WATER CHJ~RACTERISTICS

Sixty-three storm systems occurred over the Sierra Nevada during the four

winter seasons that the radiometer was located at Kingvale. A storm was defined

as a distinct cloud system, as observed on satellite photographs, that produced

precipitation and/or supercooled liquid water in the Sierra Nevada. The

majority (56) were found to fit into one of the five general groups discussed in
Section 3. The synoptic classification for all storms which occurred during the
four field seasons is shown in Table 1.

In this section, we present a case study from each of these groups. In each

case, the evolution of supercooled water near the crestline is discussed in the

context of the structure of the lal~ge scale storm system. The similarities and
differences between the case described here and the remaining cases in the same

group are discussed after each case is presented.

A. Developing storm embedded in s!rong zonal flow: 26-29 March 1985

The 26-29 March 1985 storm was a strong storm system which produced con-

tinuous, and often heavy precipitation across the Sierra Nevada for nearly 2

days. Radar evolution of this storm has been discussed by Huggins et al. (1985)
and Reynolds and Kuciauskas (1987). Figure 4 shows an infrared satellite photo-
graph of the storm taken at 0100 (a,tl times UTC), 27 March and the associated

500 mb chart from 0000. The chart on this and later figures has been projected

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