Post collapse circulation model responses, ECMWF seems a bit more on top of it
Already May 6 Toronto forecast will be off with other models based forecasts, underestimated at least 4 degrees colder. But ECMWF short term is responding well to recent massive Arctic warm up. What is left of the Canadian coldest vortice is more centered in the SW Arctic, a place already with less snow on the ground. Is set to extermination if stable there.
600 mb temperatures forecast would be more ideal, nothing is perfect! But ECMWF has some prowess, already displaying a greater warming throughout North America for the next 10 days.
GFS not so fast on its feet:
Temperatures upwards not as warmed as ECMWF but warming. I got the impression the models don't weigh as much importance to the Arctic as they should. WD May 6 2019