So What Happened to Next Week's Storm?

As mentioned yesterday, the prospect for a winter storm next week in the eastern U.S. has greatly diminished. Back when this was first discussed, I said the key was getting the northern branch of the jet stream to slow down enough to allow the pattern to amplify and get a stronger storm far enough south to allow folks to get in on some winter love. It seemed a spike in global angular momentum might help us out (see prior posts for this), but that spike has waned and it seems that once again, computer models underestimated the northern stream. I will show you this below with a map that shows the European computer model's forecast for this coming Wednesday evening from back a few days ago when it showed a big storm, and compare it to the most recent run of the same model. For those who don't know what the map means, it's fine. You should still be able to see what I'm talking about based on the features I have highlighted. Here is the map from a few days ago:














I have drawn in red the three "shortwaves", or storms in the pattern embedded in the northern branch of the jet stream, that I want you to focus on. We have one east of New England, another in west-central Canada, and another almost off the map west of Alaska. I did not highlight the trough in the Midwest, but that was the system that is our storm itself. With this model depiction, it was arriving on the scene at just the right time, and things looked great, since the system east of New England would have colder air in its wake for the storm to "play with". But the issue, again, is that in this particular la nina-like pattern, the northern stream has very often moved along faster than models have predicted (there are reasons for this, but no need to get too technical here in this discussion), and if that occurred, it would kill the chance for the winter storm as 1) colder air could escape quicker, and 2) the storm can come much farther north. Sure enough, this is what happened. Here is a map off the most recent European model run, valid the same time, Wednesday evening.














I have highlighted in red the same three features in the northern stream, and because they are moving along faster than models showed a few days ago, notice how much farther east they are. Thus, any chance of the winter storm this week is no more, and we'll have to hope another one comes along and we can get a slower northern stream with better amplification into the eastern U.S. It's a tough chore in this winter.

I should add that this still doesn't rule out parts of New England from getting snow out of this storm, as of course it is colder up there and that may still be enough. This discussion is more about how the pattern just isn't cooperating farther south.