This powerful conversion tool can be accessed by registering here. Go to Special Features. First, fill out the registration form. The next time, you can bypass the form per instructions. The site will instruct you on how to download a Java tool called Oracle Jinitiator. After downloading, go back to the main page and click on "Enter the WMO Header Database (Field Offices).
When converting from PIL to WMO, the program gives you the first line of the WMO header. The next step is to use the NNNXXX portion of the PIL header for the second line, which is the AWIPS ID line. You now have the complete WMO header and AWIPS ID.
As a further aid, this
site provides a list of all System Operations Center Change Notices.
After accessing that site, two notices are recommended: Scroll down
and select CID XR-04 for an updated cross reference between the NNN product
category identifier of the PIL header and the data type T1T2 of the WMO
header, along with the product description, sorted by NNN. For the
same cross reference, but sorted by T1T2, select the item directly
following, i.e., CID XR-05. NOTE: these advisories update automatically
and change their URL addresses, so that you must access them from
rather than by bookmarking them.