WMOD00574

• Title: Studies of Wintertime Storms Over the Tushar Mountains in Utah
• Date: 3/1/1986
• State: UT
• Country: United States
• Weather Modification - Doc Type: Report

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II show strong orographic effects. Thus we conclude that most of the

precipitation from this STORM was not orographically induced, but was

caused by storm-scale dynamical forcing. A cloud seeding approach

premised on orographic cloud physics would be appropriate only during
the early phases of this storm.

A variety of data from this STORM were condensed and are presented

as a chronology in Figure 9. Justification for dividing the STORM into

four phases is provided in this figure and in the atmospheric cross

section (Figure 7). One of the important characteristics of this STORM
was that the heavy precipitation was concentrated into about 1/10 of the
total STORM duration. The cold front passage in the Beaver Valley
occurred at 0600; and most of the precipitation fell during phase III in
association with the front. The top panel shows the precipitation rate
measured by the University of Utah observer who collected and weighed 15
minute samples at the Merchant Valley site (Fukuta and Winther, 1985).
The large variability during phase III is probably a combination of
sampling uncertainty and the large spatial and temporal changes in

convective snowfall. In the second panel from the top, the 30 minute

precipitation values from the eight recording gauges were averaged; for

each gauge, the resolution is 0.01 inches in 30 minutes, or

approximately 0.5 mm/hr. It appears that these two measurements of

precipitation rate would be in substantial agreement if the data in the

top panel were smoothed.

The cloud top temperature in the third panel of Figure 9 was

derived from the vertical cross sections of the Merchant Valley Ka-band

radar data (VAD analysis of the Doppler signal) and Adamsville

rawindsonde soundings. The fourth panel shows radiometer liquid water

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