This password protected dataset contains the Vaisala National Lightning Detection Network (NLDN) data for the region from 28-49 N and 75-103W during the PLOWS 2009-2010 field season (November 2009 to 10 March 2010). These data contain NLDN lightning stroke data with the following parameters: date, time, latitude, longitude, polarity and peak current. This dataset was made available from Vaisala, Inc. free of charge to PLOWS investigators ONLY and all users are required to abide by the Vaisala NLDN data policy to researchers: 1) Lightning data supplied by Vaisala may not be used for direct comparisons with other lightning detection networks, unless approved by the Development Center for Meteorology. This is to ensure proper lightning data interpretation, proper analysis techniques and the appropriateness of the lightning dataset to be used in comparisons. 2) Prior to submission of any publication employing data provided under this policy, Vaisala must be given the opportunity to look over elements of the manuscript related to Vaisala data for technical accuracy. Vaisala will also be open to assisting the authors by providing additional technical details if so desired by both Vaisala and the authors. Vaisala must be acknowledged as the source of the information and data. 3) There can be no proprietary or commercial restrictions on the research results, and the investigator(s) must be directly associated with an academic or research organization. 4) Archival of the data is allowed, but the data will not be shared with or sold to another party without Vaisala's expressed permission. Before access can be granted, the user must fill out and sign the Vaisala Lightning Data Research Policy to signify their agreement with these terms. The agreement is available online: http://www.eol.ucar.edu/projects/plows/documents/Vaisala_Lightning_Data_Research_Policy.pdf When completed and signed the form should be sent to: Steve Williams NCAR/EOL P.O. Box 3000 Boulder, CO 80307 or faxed to 303-497-2044. Please send an email to Steve Williams (sfw@ucar.edu) if you have any questions about this process.