WMOD00301

• Title: Precipitation Pattern Analysis - Uinta Baisn - Wasatch Front
• Date: 10/1/1990
• State: UT
• Weather Modification - Doc Type: Report

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Storm Dynamics

Large-scale Flow Patterns

Figure S. Schematic diagram showing relative importance of factors that result in precipitation

The large-scale hemispheric flow is the major factor that produced the deserts of the world located
about 30 degrees north and south latitudes. It also interacts with other factors to produce the mild
and wet climates around the earth. The large-scale flow associated with jet stream winds is the
predominant factor that interacts with other atmospheric features and influences winter precipitation
patterns in Utah. These patterns are large-scale guides to precipitation producing storms.

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Figures 6 and 7 show schematics of general large-scale hemispheric flow over the Western United
States. Figure 6 represents the type of large-scale flow that persisted during the wet, 1971-1975 and
1979-1988 winters. Figure 7 represents the large-scale flow patterns that persisted during the dry
winters of 1976-1977 and 1989-1990.

Droughts and wet spells in the State of Utah are inter-related with events on a global scale. The
position and movement of the Intertropical Convergence Zone (lTCZ), EI Nino, ocean water surface