A couple of days ago, people were posting day 10-16 charts as proof the zonal conditions would continue. Now they are showing cold and heights building into Greenland, the charts are suddenly unreliable again. The trend starts at day 11, so we should see tomorrow if the other models give support to the GFS, if they do then I'd say it's odd on that heights will build into Greenland. What happens after that, is open to question. It could just be a short cold snap, or it could be something more sustained.