Big Difference Between ECMWF and GFS

A sign that the season has changed by way of the very large difference bwteen the ECMWF forecasts versus the GFS at end of next week. The ECMWF 500 mb forecast valid at 168-hours is shown below. Minimum heights over western Arizona are lower than 5580 m.

As has been the case last couple of winters for most strong systems, the GFS is considerably weaker with its forecast. The GFS is also about 12-hours faster than the ECMWF - so I'm comaring the 156-hour GFS with the 168-hour ECMWF - not quite legit but GFS has its lowest heights then. Note that there is a large area of the Southwest with ECMWF 500 mb heights 100 m to almost 200 m lower than those forecast by the GFS. Snow possible in Flagstaff with this system, or mostly strong, chilly winds?