Iirc from past experience, S and E corrections tend to occur more often when developing blocking up top is either being modeled too weak or incorrectly wrt timing (too slow developing on guidance vs reality). I think this could be one of those times where S and E corrections have increased possibility. Now during Archambault events where blocking is waning or the NAO is relaxing, we tend to see the N and W corrections more frequently. Again, my thinking may be wrong but this is how I remember it from my experiences.