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<br />20 <br /> <br />nondivergent.) Dividing the speed into distance travelled gives an <br /> <br />initial value of the time of travel. Since a parcel's speed changes <br /> <br />with time, the initial time of travel is used to interpolate with time <br /> <br />and on the same pressure surface in the appropriate directions, a modi- <br /> <br />fied velocity. To determine the travel time equation (6) is evaluated, <br /> <br />v = Vo + 1Y- dt <br />ato <br /> <br />(6) <br /> <br />V is then divided into the distance to give a better estimate of the <br /> <br />travel time. The process could be repeated but higher order terms <br /> <br />would make only minor contributions. Done at regular pressure levels, <br /> <br />this procedure yields profiles of the travel time from the upwind sta- <br /> <br />tion. The same column of air can then be sampled over all three stations. <br /> <br />Minturn wind data are used to evaluate equation (6). Resulting time of <br /> <br />travel profiles for 1500 are shown in Figure 8. <br /> <br />Balloon paths from Minturn during or near the precipitation period <br /> <br />are shown in Figure 9. This data is used to determine the average drift <br /> <br />of the balloon as a function of pressure. The paths also serve as a <br /> <br />check on the wind direction. Notice that the balloons launched during <br /> <br />the precipitation period have very similar tracks approximately follow- <br /> <br />ing the coordinate heading of 1500. <br /> <br />Snowboard data are shown in Figure 10. The data were taken on the <br /> <br />16th of January and represent a 24-hour accumulation of snow. The <br /> <br />Hoosier Pass data were taken starting from near Alma at 0940 to 1144 at <br /> <br />Breckenridge. Fremont Pass data were taken starting at 1145 near Lead- <br /> <br />vi11e to 1445 near Frisco. As noted, these data are biased toward lower <br /> <br />elevations and only provide qualitative checks of calculated'precipitation. <br />