This interim report presents the results to date from the Lamar Low-Level Jet Program (LLLJP) that has been established as joint effort among the U.S. Department of Energy (DOE), the National Wind Technology Center (NWTC) of the National Renewable Energy Laboratory (NREL), and General Electric Wind Energy (GE Wind). The purpose of this project is to develop an understanding of the influence of nocturnal low-level jet streams on the inflow turbulence environment and the documenting of any potential operating impacts on current large wind turbines and the Low Wind Speed Turbine (LWST) designs of the future. A year's record of detailed nocturnal turbulence measurements has been collected from NREL instrumentation installed on the GE Wind 120-m tower in southeastern Colorado and supplemented with mean wind profile data collected using an acoustic wind profiler or SODAR (Sound Detection and Ranging). The analyses of measurements taken as part of a previous program conducted at the NWTC have been used to aid in the interpretation of the results of representative case studies of data collected from the GE Wind tower.