Yesterday we pointed out that a cold pattern for October was beginning to evolve over North America. It was pointed out that the most similar pattern to what is forecast by the longer range models is mid-to-late October 1976. That period saw temperatures from 10 to over 20 degrees below average along with accumulating snow all the way down to the level of Lake Superior. Today, the model forecast has not changed (Image 1 above). It is still forecasting a set up similar to the third week of October ??76.
While a deep upper-level trough is forecast to set up and bring the cold, there still is no cold air in Canada except in the high arctic (Image 1 above). Since this will be the first outbreak of the season and there still is not much snow on the ground except in the far north (Image 2), it will take a while for the cold to develop. Currently, moderately cold air is streaming southward through central Canada due to northwesterly winds blow ahead of high pressure off the West Coast (Image 3). This general pattern is forecast to continue and by next Friday, the European model shows some very cold air for October flowing from the arctic southeastward into the Upper Great Lakes (Image 3). This would mean a good deal of lake-effect precipitation. In fact, we expect it this weekend, though much of it will be in the form of rain. If the model forecast is correct, there will be accumulating snow over at least portions of northern Upper Michigan during next week.