Jul 3, 2017

The More Extreme Nature of North American Monsoon Precipitation in the Southwestern U.S. as Revealed by a Historical Climatology of Simulated Severe Weather Events

Thang M. Luong, Christopher L. Castro, Hsin-I Chang, Timothy Lahmers, David K. Adams, and Carlos A. Ochoa-Moya
Journal of Applied Meteorology and Climatology
  • Evaluates long-term changes in North American monsoon (NAM) precipitation intensity in the Southwest U.S. through the use of convective-permitting model simulations of objectively identified severe weather events during “historical past” (1950-1970) and “present day” (1991-2010) periods
  • Defines severe weather events as days when the highest atmospheric instability and moisture occur within a long-term regional climate simulation
  • Performs severe weather event day simulations and compares them to available observed precipitation data to evaluate the model performance and verify model-simulated trends
  • Finds that a statistically significant long-term increase in atmospheric moisture and instability is associated with an increase in extreme monsoon precipitation in observations and severe weather event simulations
  • Finds that precipitation is becoming more intense within the context of the diurnal cycle of convection
  • Concludes that a more favorable thermodynamic environment in the Southwest U.S. is facilitating stronger organized monsoon convection during at least the last 20 years