Lab III: Orographic Precipitation/Rainbands
Due: Monday 27 March
Problem 1:
Orography plays a major role in determining the mesoscale distribution
of precipitation over the western United States and greatly influences the
climate, ecology, and economy of the region. In Utah and other adjoining
states, water rights, irrigation, and flood management remain among the
most important and controversial political issues. Meteorologists
and hydrologists in this region must thoroughly understand how the local
terrain influences precipitation distribution from hourly to
annual time scales. To better understand the climatological
distribution of precipitation over the western United States, use
annual precipitation analyses from the Oregon Climate Service to describe the
relationship between terrain and precipitation in (a)
Washington and (b) Utah. Explain the
meteorological reasons for the observed precipitation distributions.
Problem 2:
On a case by case basis, the interaction of synoptic and mesocale flow
with the local terrain can produce precipitation distributions that deviate
drastically from the climatological averages examined in problem one.
For example, Alta ski area (8500' MSL) receives 4 times the annual
precipitation of Salt Lake City Airport (4200' MSL), but on a case by case
basis this ratio can vary drastically. As a meteorologist, it is
important to understand how synoptic and mesoscale weather flow patterns
and features effect the mesoscale distribution of precipitation in
complex terrain. Using Parsons and Hobbs (1983),
describe how the terrain of western Washington effects the
evolution of (1) warm-frontal rainbands, (2) warm-sector rainbands, (3)
narrow cold-frontal rainbands, and (4) wide cold-frontal rainbands.
Speculate on how the interaction between the terrain and the synoptic
scale flow produced the observed evolution in each case. Finally,
describe the implications of this study for understanding precipitation
events in northern Utah.