I was sentenced to 2 years probation for underaged drinking. Attendance at AA was a condition of probation. I submitted AA logs to my PO with some forged entries and now I have been ordered to appear in court for probation violation. What will happen to me?

Up to the judge, my guess at least a few weeks of jail to get your attention, then back on probation.
But they can
1. send you to jail for the entire probation period
2. warn you and send you back on probation
3 increase the report times and require closer watch on probation
4. give you a few weeks or months jail and back on probation