Weather to turn more volatile next week, but no sign of snow Posted at 01:58 PM ET, 11/19/2012 Colder than normal air has gripped the region for much of November, but we still have yet to experience a day with highs 45 or lower, or a legitimate chance of accumulating snow. Could the pattern be changing to one decidedly more wintry as December approaches? I can only say partially. Yes, our shots of cold will inevitably become more intense, but their staying power is in question - and the storm track may be too far north for snow. NAO 15-day forecast from two model groups (NOAA) There's fairly strong model agreement that the North Atlantic Oscillation (NAO) will switch to its negative phase this weekend and lock in for a while. When the NAO is negative, it's an indication that the jet stream is taking a dip over eastern North America, allowing Arctic Air to plunge southward. PNA 15- day forecast from two model groups (NOAA) Although the NAO may support cold weather, the pattern in the Pacific Ocean may counter the chilly Atlantic setup. The Pacific North American (PNA) pattern is forecast to be negative (at least through the end of November), favoring a dip in the jet stream along the West Coast (and likely very wet and snowy conditions in the Pacific Northwest). That would actually tend to support mild air pushing into our region as the jet stream lifts north. The end result may be a fairly volatile pattern establishing itself next week - in which we see-saw between warm and cold - in stark contrast to the stable pattern this week (with consistently moderate temperatures). Although details are highly subject to change, here's a quick look at what we might expect in the 7-14 day window with the strong caveat that details and timing are highly subject to change: European model simulation of storm forming over Missouri in the middle of next week (Tuesday night) (StormVistaWxModels.com) This weekend into early next week: Cold, dry Middle of next week: Turning mild, chance of rain Late next week: Chance of rain, then turning colder I talked to Wes Junker (CWG's winter weather expert) earlier today and we both agreed that snow potential will probably be confined to our north and northwest next week. Areas from the northern Plains through the Great Lakes and then maybe into New England will have a better chance for winter weather as a possible storm develops in central Plains in the middle of next week and heads northeast.