Radar observations during NAME 2004. Part II: Preliminary results

Two-dimensional radar-based regional data products from NAME 2004, detailed in Part I of this study - as well as case studies using 3-D volumes from the NCAR S-Pol radar - are being used to understand the climatology of convection in the heart of the North American Monsoon in northwestern Mexico and the Gulf of California. In particular, the relative importance of Gulf surges and easterly waves in organizing and modulating convection is being studied. Here we report on preliminary results from this work. In particular, we note the typical diurnal behavior of convection along the sea breeze front over the coast, as well as over the complex terrain of the Sierra Madre Occidental (SMO), which peaks in the late afternoon as expected. In addition, we note very active days (with a 3-5 day return cycle consistent with passing easterly waves) wherein the typical diurnal convection evolves into more organized systems and propagates from the SMO, to the coastal plain where it merges with any existing sea breeze convection, and finally out to sea over the Gulf of California. Using a case-study approach, we study the evolution of convection on these active days in more detail, to better understand the links between the diurnal cycle, easterly waves, and storm development during the North American Monsoon. If time and space allow, we also will present on significant early morning convection caused by the land breeze, as well as convective modulation by Gulf surges.