It's still (astronomical) summer and it's going to feel like it for the next handful of days with warm, humid weather in the forecast. It's WAY too early to put out an official winter forecast. But I thought I'd share a few thoughts on the upcoming winter anyway. With the important caveat:
THIS IS NOT A FORECAST.
THE OFFICIAL WINTER FORECAST WILL BE ISSUED ON AIR AND ONLINE AROUND NOVEMBER 1
Ok, now that we have that out of the way. This post will not dive into ALL the factors that I surely will be looking at when I compile the forecast in 6 weeks. I'll just touch on a couple here.
#1 The Winter Is Likely To Feature A Weak El Nino
Remember, El Nino is a phenomenon having to do with water temperatures in the Pacific Ocean and how they compare to average. El Nino is a warming of the waters in the eastern Pacific, near the equator. What does this have to do with our weather?? Well, the oceans and the atmosphere are one big system and what happens in the oceans can influence how the atmosphere behaves.Right now odds favor an El Nino this winter although the odds of it being a "neutral" winter are not negligible (at 31%). The strength of an El Nino is important. Weak El Ninos tend to result in more "surprises" and more variance than strong ones. In other words, the range of outcomes is greater than during a winter featuring a strong El Nino.The location of the warmest water (compared to average) is also important. A "standard" El Nino sees the warmest water banked up against South America. But there is a special flavor of El Nino called "modoki", which sees the warmest water farther west.These 2 flavors of El Nino often produce winters over the US that are quiet different. Odds favor a "modoki" this winter.Modiki:
#2 The "QBO" Or Quasi-biennial Oscillation Is Going From VERY Negative (Easterly) To Near Neutral
Say what? The QBO refers to the oscillation of river of air at very high altitudes in the atmosphere. It switches directions at regular intervals and has been shown to have an impact on weather patterns in the northern hemisphere winter. It was very "negative" or easterly last winter through this summer but is trending back toward neutral.Again, so what?
Winter Outlooks Are Largely Based On Looking At The Past
Making a seasonal forecast is tough but thankfully we have lots of data to look at., including detailed records of the past. So, we look for years with similar setups and see what happened. For the purposes of this post, I'll just look at past years with weak modoki El Ninos and a QBO trend similar to this fall. When I do the "real" forecast, I will be looking at much more than this.Temperatures (averaged together) during winters with weak modoki El Ninos:Finding years with a weak modoki El Nino AND a QBO trending from very negative back toward neutral is tough. Only found a few. Average them and you get this:Precipitation anomalies: Using these factors alone, the winter of 1968-1969 is the best overall match. Temperatures that winter:Pretty cold winter. Snow was nothing to write home about. A bit below our average in the lower/mid 60s actually.Again, the forecast will come out sometime around November 1. This just gave you a little peek behind the curtain. I love the challenge of the winter forecast and look forward to trying to beat the atmosphere this year!