AWOS 3P is a specific AWOS configuration. The "IIIP" denotes the types of sensors that are included and what types of data are output.
Below are the AWOS configurations defined by the FAA:
· AWOS A: Altimeter setting
· AWOS A/V: Altimeter setting, visibility
· AWOS I: Altimeter, wind speed/direction, temperature, dew point, and density altitude
· AWOS II: The same as AWOS I plus visibility
· AWOS III: The same as AWOS II plus precipitation accumulation, cloud height, and sky condition
· AWOS III P/T: The same as AWOS III plus present weather and/or thunderstorm detection
· AWOS IV Z: Same as AWOS IIIPT plus freezing rain detection