I’d like to write a little bit about the next significant storm threat, which seems to be lining up for the middle of next week. For much of this winter we have been in a blocking pattern, resulting from a strong high pressure system over or near Greenland, which has been forcing the jet stream to drop from Canada into the US, with a trough of low pressure in the eastern US often resulting in cold air and snowstorms from the South to the Midwest to the Northeast. We’ve seen plenty of that since Christmas.
The overal l pattern does not appear to be changing that much, however there are some signs that the blocking pattern may relax to coincide with the next storm threat. What does this mean? Well, the most reliable longer range computer model this winter, the ECMWF (or, the Euro as I & others affectionately call it), is responding to this possible break in the blocking pattern by indicating the storm next week may take a track further west than many of the recent ones have. This would allow warmer air to move up the East Coast and bring a better chance of rain versus snow. However, one of the other longer range models does not relax the blocking as much, and therefore keeps it colder, showing a storm track more to the east, resulting in a colder and snowier result for much of New England. So early on, you can see what kinds of issues a meteorologist faces when thinking about upcoming weather.
Logic says it should be the Euro model that will have this handled better, because it’s done well most of the winter. But just because a model has done well doesn’t mean it will hit everything. So you have to look for clues that may tip you off that the model may be making an error. Just the simple fact we’ve been so cold and have such a deep snowcover can mean that computer models can make errors, and forecast warmer conditions than will occur. So that will be one factor to consider. Also, the model that is giving the colder solution was one that did a fairly decent job predicting the details of the most recent big storm, so there is some pull to want to buy what it says. Confused yet? So am I…
But, having seen these conflicts before, I will wait a while before I start to come up with solid ideas. But a very early guess is that the truth lies somewhere in between. And we may see a storm that tries to stay further west, only to redevelop on the coast. If pressed to a forecast of rain vs. snow right now for next week, I’d have a slight leaning of white versus wet. Time will tell. And for me, this will be fun to follow, especially since I’m looking to break out of a forecasting slump!