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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . that seeded crystals formed over the windward slope would typically have about 30 min growth time while crossing the mesa. Exclusion of mesa-top precipitation rates exceeding 0.15 mm h-1 (0.006 inch h-1) resulted in the removal of many hours with no SL W during conditions otherwise favoring its formation; that is, southwest flow of moist air at relatively warm supercooled temperatures. It might be expected that moderate to heavy snowfall rates would convert all available SL W to snow. However, that precipitation rate exclusion criterion also removed over 50% of the high-SL W data, demonstrating that much SL W was often present during periods of significant natural snowfall. This finding is contrary to suggestions from the Park Range, but in agreement with recent observations from the Wasatch Plateau of Utah (Super and Heimbach 2005a). Even heavy natural snowfall does not always remove all available SL W, especially when its production rate is high because of relatively strong winds forcing moist air up and over mountain barriers. This result is at variance with the concept that storms producing moderate to heavy snowfall rates are not seedable. Boe and Super (1986) defined a "SL W episode" as the continuous presence of radiometer- observed SL W for longer than 2 h. If SL W was again detected within 2 h of the first 2 h block, the episode was considered to be continuing. A total of 115 episodes resulted from the 5-mo dataset, with 50% of them less than 3 h in duration. Only 12% were longer than 12 h. However, the 50% of episodes less than 3 h long contained only 14% of the total hours of S L W while episodes longer than 5 h comprised 80% of the total hours. A distribution was given of 1 h average SL W amounts observed by the radiometer (their Fig. 5). The distribution was highly skewed, with 57% of all SL W hours having 0.10 mm or less, and the median value 0.08 mm. When converted to SL W flux by considering the wind speed, those many hours with 0.10 mm or less contributed only 16% of the total flux for the five months. The relatively infrequent hours with high SL W amounts contributed significant fractions of the total flux. This skewed distribution might be anticipated, and has since been found over other mountain barriers. It has long been known that snowfall rates, which require SL W presence, are also highly skewed. Many hours have very light snowfall rates and relatively few hours have heavy rates. Rauber, R. M., L. O. Grant, D. Feng and J. B. Snider, 1986: The characteristics and distribution of cloud water over the mountains of north em Colorado during wintertime storms. Part I: Temporal variations. J. Climate Applied Meteorology, 25, 468-488. A scanning dual channel microwave radiometer was operated at 15 deg tilt above the horizon, scanned through 360 deg of azimuth about every 15 min. The unit was in a "hole" near Steamboat Springs, at an elevation of2050 m (6726 ft), with a minor ridge to the west and major ridge, the Park Range, to the east (see their Fig. 2). Time histories of SL W content were shown by azimuth. Greatest SL W amounts were consistently over the windward (west-facing) slopes of the Park Range. This finding indicates that forced uplift of moist air over the barrier, sometimes associated with the release of weak embedded convection, produced the zone with greatest SLW amounts. Thus, the most seedable zone would be expected to be over the windward slopes of the main mountain barrier. A secondary maximum was often observed over the minor ridge west of the radiometer. Unfortunately, the radiometer location required that its beam scan some distance above the windward slopes to avoid viewing the rugged terrain. A better location would have been at the SPL, elevation 10,370 ft, and due east of the radiometer on the west edge of the 33