Interesting pattern going on, right? Wrong. The current pattern that we are in consists of just about everything that a weather fanatic hates. It is a very flat and progressive pattern, that features numerous fronts sweeping through the eastern third of the nation, bringing warm weather ahead of the fronts, wet weather while the fronts pass overhead, and then brief cold shots once the fronts move through the area. The problem is, these are cold SHOTS. 24-48 hours after the cold weather sweeps through, we begin to warm up again, and the pattern starts right from the beginning and happens again and again. Why are we in this pattern and when is it going to end? Well I hope to answer those questions here today.
Let's start with why we are getting our current setup. This is mostly due to teleconnections that can sometimes be your best friend... but right now is our biggest enemy.
So let's quickly go through each of these individually. We'll start with the NAO:
Here's my problem with the NAO, and the NAO's problem itself. The NAO has it's own, "forecasting pattern". These models will show the NAO taking a dip negative 10-15 days in advance. Then we all jump onto the cold train, talking about how the NAO is about to take a dip negative in 10-15 days, and then we are in business. Then 3-5 days go by, and all of a sudden, the NAO looks like it may go neutral rather then negative. Then 3-5 more days go by, and we see the NAO is shown positive all of a sudden by all the models. And it is the same thing again and again. Look at the chart and start with October 16th and go all the way to December 3rd or 4th. You will CLEARLY see the pattern. There is a rise to +1 and then a dip to neutral, and then a rise to +1 and dip to neutral, and the same thing keeps happening. WE NEED that NAO to go negative before we start getting excited about the cold and snowy weather.
AO:
The AO is a similar story, and has similar effects on the eastern third of the nation when it goes negative. Not the same pattern though. The AO has been positive for a while and shows no real signs of going negative anytime soon. That's a problem. Just like the NAO, until we can see this dip negative, we are stuck in our current pattern.
PNA:
Oh the PNA. The only good news for the cold weather. Typically when we see a positive PNA, we get the cold weather to pump into the eastern third of the nation. As you can see from the chart, the PNA has been, and still is, very consistent in showing a positive read after the 22nd or 23rd of November. This normally would be very good, but will do nothing with a positive NAO and AO. Therefore, until we get those two to do something, the PNA will not matter.
Now that we have a good grasp on the pattern setup from now through early December, we can start talking about the upcoming storms, starting with our "pre-thanksgiving storm".
Pre-Thanksgiving storm:
Folks this storm is rather simple in my opinion... All snow is contained north of I-90... Maybe a little back end snow south, but not enough to make a note of it...
The next storm we begin to look at is toward the very end of the month. It looks like we'll see a very complicated storm track across the country MAYBE bringing some midwest backend snow, but even that looks rough at this point. This storm will likely be a MAJOR rain and wind maker for the Northeast. MAYBE some mountain and extreme interior snow, but again that looks rough as well. I've been watching this storm for a while now on the models, and while pretty far away, it looks like it may have at least SOME change in the overall pattern. It's possible we see a change in the STORM TRACK with this system, as it will do a lot of interesting things to the overall pattern. One thing it will NOT do though, is help drag in cold air. We need the teleconnections to do that (NAO, PNA, AO, etc.)
Those two storms are as far out as I want to go for now. In between these two storms though, there will be quite a warm up. The 24th through the 27th may be very warm and dry. Enjoy it while you can though, cause now we're going to start talking about winter and why people SHOULD NOT be worried about the current pattern.
We start around December 5th. The teleconnections should still be non conductive for any sustained cold. That means our pattern continues. I STILL REMAIN CONFIDENT WE SEE OUR PATTERN CHANGE AROUND THE 10TH OF DECEMBER. If I start seeing though, that the teleconnections don't favor that time period, I will have to change my forecast. Not to worry though. Last year we did not see sustained cold until later in December and we did not see our first snowstorm until December 26th! There is plenty of time folks.
What we need to focus on is these teleconnections. Take your minds off the models in terms of seeing if a winter pattern is coming in the long range. Even if it appears that way, like it does on the GFS, it will not verify unless we get those teleconnections to corporate. Once again, I expect that to happen around the 10th of December.
Hoping this might help:
Have patience my friends and enjoy this November pattern. It will not last forever! In the meantime, get ready for my official 2011-2012 winter forecast coming out on December 11th!
