Its a long time since I've seen the AO forecast to go this negative in a long time, we just need this to materialise and help weaken the PV significantly enough to allow blocking to develop to the north of us (I know this is no guarantee for cold snow for us though).
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif
The NAO looks like staying neutral to slightly positive for a while longer, in which case we will struggle to get the Atlantic blocked.
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif