Variability of the North American Monsoon System (NAMS) may be related to global-scale climate variations, local surface influences, or a combination of the two. Here we use the Regional Atmospheric Modeling System (RAMS) to investigate these hypotheses. The experimental design is described, highlighting new additions to RAMS for use as a regional climate model (RCM). These include the Kain-Fritsch cumulus parameterization scheme and heterogeneous initial soil moisture from the Variable Infiltration Capacity model. The influence of time-varying summer teleconnection patterns related to the El Nino Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) is investigated by two sets of dynamical downscaling experiments. In the first set, observed summers with strong ENSO-PDO signatures in Pacific SST are simulated using NCEP-NCAR Reanalysis data as lateral boundary forcing. RAMS captures differences in NAMS evolution between observed years with different SST signatures. In the second set, the lateral boundary forcing is from the NASA Seasonal to Interannual Prediction Project (NSIPP) general circulation model (GCM). The four-month NSIPP GCM runs are prescribed with: 1) climatological SST, 2) climatology plus ENSO-related SST, and 3) climatology plus PDO-related SST. The teleconnection patterns and evolution of summer climate which appear in these idealized simulations correspond with observations. Future proposed work with RAMS testing the sensitivity of NAMS to antecedent soil moisture and vegetation, which use the current set of experiments as a control, is also outlined