0z GFS ensembles very bullish on a strong eastern trough and a persistent east based - nao block that will stick around and cause this trough to dig deeper and stay in place for a while. This GFS run is indicating departures of MORE THAN 18C BELOW NORMAL IN AN 8 DAY PERIOD! This area will form across much of interior B.C, parts of Alberta, Saskatchewan and Manitoba before moving southeastwards for the end of october and beginning of november. Something important to note is we may be seeing daily departures of over 10 degrees below normal for several days in area away from the great lakes but this extreme cold will not last as long as it did in the pacific northwest. We will see an initial shot in the east and then it may stick around for a while with blocking over the top before recharging.
The indicies support this and have moved to a -NAO,-AO,-EPO,+PNA look for the end of october and beginning of november period.