It looks like you received a number of TCP packets (that I would assume were blocked, though could have been allowed) that the log data indicated were all missing SYN flags. You can see this rule if you go to Build > Rules and search for the "inference" type rules, or "PortScan". If you open the rule and look at the threshold, then open the advanced threshold, you can see the logic for the rule.
You might want to increase the threshold on your network if it's firing too frequently or doesn't actually look like a PortScan. Fun fact - you can actually see the original events that led up to this from your LEM Console (filters OR search) by clicking on the event then going to Explore > Event. It'll show you the events that came before and as a result (i.e. 10 TCPTrafficAudit events happened with Missing SYN Flag, then they triggered the TCPPortScan, which then triggered the email to be sent).
On top of this question I would like to know if my network traffic can see the rise ...