The YSI MultiLab IDS meter outputs a true barometric pressure reading of its location, which is dependent on elevation above sea level.
Local weather services typically use a corrected barometric pressure reading, which corrects the reading to sea level.
To approximate the true barometric pressure reading from a corrected barometric pressure reading, use the following equation:
True barometric pressure [mmHg] = Corrected barometric pressure [mmHg] - (0.025 * local altitude [feet] )