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994 JOURNAL OF APPLIED METEOROLOGY VOLUME 27 b. Storms with meridional flow characteristics near 400N Storms in a meridional dominated flow differed from the zonal flow storms in the amplitude of the wave systems. The wind direction, which was determined by the position of the wave relative to the mountain, was a key to the existence of supercooled water over the Sierra Nevada. For this reason the regions where su- percooled water was present in meridional storms were much different from those regions in the zonal storms. Storms associated with a meridional flow pattern at 400N were grouped into two categories. The first in- cluded cutoff lows and narrow high amplitude troughs near 400N. The second included short waves digging down the east side of a longwave ridge. I} CUTOFF LOW OR LARGE AMPLITUDE SHORT- WAVE NEAR 400N A schematic portrayal of the flow in a cutoff low near 400N is depicted in Fig. 3d. The cutoff center occurred between 350 and 400N latitude. This synoptic configuration provided strong southerly to southwest- erly flow ahead of the storm systems, shifting to north- erly and sometimes northeasterly after trough passage. The cutoff systems had a gradual easterly progression that was usually less than 15 m S-I. This category also included large amplitude short waves. The observed wind shifts in the large amplitude short waves were very similar to the cutoff circulations. However, the speed of the large amplitude short waves was much more rapid than the movement of cutoff circulations, resulting in shorter storm periods over the Sierra Nevada. 2) LARGE AMPLITUDE LONG-WAVE PATTERN PRO- DUCING COLD NORTHERLY STORMS This group of storms represented the coldest storms encountered in the Sierra Nevada. A schematic rep- resentation is shown in Fig. 3e. This category included rapidly moving storms that were forced over a large amplitude ridge to the west and then dug from north to south over the project area. Winds were westerly near the time of the trough passage, providing the greatest mountain-normal wind component. After the trough passed, winds shifted to northerly and often northeasterly, which eliminated the mountain-normal wind component. The variations in this storm type depended on the storm trajectory. An inland trajectory took the short- wave over Idaho and down through Utah. The more inland the trajectory, the warmer the storm was over California. Very little frontal structure and little pre- cipitation were observed in storms with these trajec- tories. In contrast, storms with trajectories directly over the west coast had colder temperatures with more pre- cipitation. The precipitation associated with the storms was usually short-lived, occurring over a period of 2- 6 hours. Surface fronts were either weak or not evident. Systems with offshore trajectories had temperatures that were extremely cold and snow often occurred near sea level. Precipitation amounts were greater than in storms with onshore or inland trajectories and 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 characteristics Sixty-three storm systems occurred over the Sierra Nevada during the four winter seasons in which the radiometer was located at Kingvale. A storm was de- fined as a distinct cloud system, as observed on satellite photographs, that produced precipitation and/or su- percooled liquid water in the Sierra Nevada. The ma- jority (56) were found to fit into one of the five general groups discussed in section 3. The synoptic classifica- tion for all storms that occurred during the four field seasons is shown in Table 1. In this section, we present a case study from each of the five general groups. In each case, the evolution of supercooled water near the crestline is discussed in the context of the structure of the large-scale storm system. The similarities and differences between each case and the remaining cases in the same group are discussed after the case is presented. a. Developing storm, embedded in strong zonal flow: 26-29 March 1985 The 26-29 March 1985 storm was a strong system that produced continuous, and often heavy, precipi- tation 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 photograph of the storm taken at 0100 (all times UTe) 27 March and the associated 500 mb chart from 0000. The chart on this and later figures has been projected to conform to the satellite photograph. Time/height cross sections of equivalent potential temperature, temperature, relative humidity and winds from soundings at Sheridan, Cal- ifornia for the 48-h period from 0900 26 March to 0900 28 March are shown in Fig. 5. Figure 6 shows the radiometric measurements of supercooled water during the storm and the precipitation rate measured at the radiometer site at Kingvale. At 0000 UTC 27 March, a wide trough system was present over the northeast Pacific. Strong, near-zonal flow was present over central California and westward into the Pacific. The storm system had already moved into the Sierra Nevada at 0000, and precipitation in excess of 6 mm h-1 was falling at Kingvale. Distinct warm and cold fronts were present in this storm. The warm frontal period extended from 0900 UTC 26 March to 0200 UTe 27 March. At 0900, the warm