The good news is that -NAO/-AO in December is often followed by more bouts of blocking later in the winter. there are a few exceptions...89-90 it disappeared and never came back....
I think this is what has some down-this map is from 11/30 for valid date 12/13--looks like it was too fast in the end which makes sense-models always too fast for pattern changes and also too fast to break them down