Not so fast with Winter....(11-24-12)
As you look outside your window today, it sure looks like winter is here. We knew is was coming, but after a week and a half of sunny, dry, windless weather here in central New York, the snow in the air today is still a shock to the system. Lake effect snow advisories are up for parts of central New York as of Saturday afternoon. To see how much snow is expected, make sure you check out our latest snowfall forecast map.In spite of the winter-like weather today and into next week, I wouldn’t be so quick to say we are locked into a prolonged winter pattern. I’m going to spend this blog focusing on the longer term. I’ve been looking at the computer models out in time a week to two into the future. I keep seeing signs that by the start of December our temperatures are going to go back above normal. The first sign comes from the ensemble means from both the GFS and European model. This is for the period December 1st through the 4th.
Now I don’t expect a period of weather quite like we just went through leading up to Thanksgiving. First, keep in mind, by early December the average high temperature in Syracuse is about 40 degrees. We could end up in the mid 40s and still be considered ‘above normal.’ In addition, this time around the jet stream is farther south so I’d expect more precipitation this first week in December. However,odds are we’ll be looking at more rain than snow the first part of December. We don’t have forecast data from the European model that goes out beyond 10 days but we do have that information from the GFS and it points toward above normal temperatures for a while beyond December 4th.
I’ve spent a couple of paragraphs explaining why we should have above normal temperatures early in December. There is, however, one piece of data that does give me some pause and it is the NAO (North Atlantic Oscillation). This is a measurement of pressures out in the Atlantic Ocean and when this index is in its negative phase, we tend to be colder than normal here in the Northeast. Here are a couple of forecast of the NAO. Focus on the bottom two graphs.
The key to why the European and GFS models are still forecasting above normal temperatures, in spite of a strongly negative NAO, could be the equally negative PNA (Pacific-North America) Index. The forecast of that index is shown above the graphs of the NAO. Our coldest weather is when there is a positive PNA in the West and a negative NAO in the East
The bottom line is it looks like the weather over the next few days will be just a tease for winter enthusiasts. Colder weather probably won’t have much staying power once we get past the end of November.
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