We have made it to "the reprieve". The warm weather has finally given way to more seasonable temperatures but it remains extremely difficult to get excited about the outlook going forward. In short, the pattern continues to be plagued by many of the same problems discussed in the blog in previous entries. The repetition of these features, particularly in the Pacific is making me feel like a boxer against the ropes getting his head beat in as he tries to avoid a knock down. The next 10 or so days should be better verses what we have seen so far this December but I want "change I can believe in" to borrow the Obama slogan and I have yet to see it.
We finally have our hands on some arctic cold which is a start. As we move into Monday the cold will get re-enforced as a clipper system moves through the eastern Great Lakes and spreads what should be a light accumulation of snow to the region late Monday the 19th. This is not the system we have been watching however, that system will begin its journey in the southern Rockies, move into the Red River Valley later Monday and track across the rest of the country Tuesday. We should see precipitation from this feature either late Tuesday into Wednesday but although the track of this system is not nearly as unfavorable as previous, our supply of cold air will quickly become stale and will struggle to hold its ground. At best we can expect a wet snow out of this but it is possible for a changeover to mixed precipitation, freezing rain or even a period of rain. Everything should be over and done with by Wednesday evening and a gradual return to colder conditions.
The return to chill late in the week should be the start of another stretch of at least seasonable temperatures and possibly even below normal temperatures for a day or two. The return to chill late in the week might also include some type of mixed precipitation to snow event. This would likely take the form of a wave of low pressure energizing a slow moving cold front. This however along with the cold weather that follows should preserve the period between the 24th and 28th of the month which i know is a big one for vacation planners. During this period, there is no evidence of a major snow event but clipper systems and weaker features could certainly provide some fresh powder to the region Christmas Day or the two days that follow.
The brief amplification of a western North American upper ridge will play its hand in that aforementioned 24th-28th period but there continues to be a lack of evidence that this change will be of a permanent. Instead, the broader weather map reverts back to the features that have hurt us. Height rises and upper ridging in the Mid-latitude Pacific coupled with the potential redevelopment of an poler vortex over Alaska. These are the main ingredients to the zonal flow scenario we have seen now for 5 weeks. The Arctic Oscillation and North Atlantic Oscillation continue to run positive revealing the lack of blocking at high latitudes and it is only the PNA providing some support over the next 10 days that is providing any real aid.