The intent is that 12 of the 19 reasons under clause 60.1 the Contractor is obliged to notify within 8 weeks of becoming aware of the event. The assumption otherwise is that the issue concerned did not have an effect on cost or planned Completion. If the Contractor at the end of the project comes with lots of historical "claims" they will be too late for these. There is no particular obligation of the PM to remind the Contractor to notify these, but certainly you would hope in "the spirit" of the Contract they would remind them if they knew they were. The PM will have known it has snowed or rained a lot last month, but will not know if it is a more than 1 in 10 year event for which would then become an Employer risk.
The seven that the Project Manager are obliged to raise are 1,4,7,8,10,15&17 (guidance notes lists these out within 61.1). The Contractor is not time barred on any of these items. All the others they are obligated to notify within 8 weeks. Notification simply requires the Contractor to notify what the event is, an why it is a compensation event.