Why does the barometer reading on my YSI 4010 MultiLab IDS meter not match the reading documented by my local weather service?

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] )