Time once again for my annual Winter Forecast. Please feel free to watch either the short version that aired on 21 Newshttp://www.wfmj.com/clip/13870419/erics-annual-winter-forecast-short-versionOr the long, much more detailed version:https://www.youtube.com/watch?v=mDrBDJbjkB4&t=820sBefore we get to the forecast, let's do a quick recap of recent winter weather across our region. It many be surprising to some that last winter will go into the record books as fairly snowy! 69" at the Youngstown-Warren airport is a few inches ABOVE average. Temperatures? No surprise there...it was our 2nd consecutive mild winter.Some highlights of last winter. How did we pick up that much snow when January and February were so balmy? December and March were quite a bit snowier-than-average:4 of the last 5 winters have been fairly "extreme" temperature-wise. 2011-2012 was quite mild; 2013-2014 and 2014-2015 were harsh and 2015-2016, 2016-2017 were quite mild.In the snow department, most winters have been snowier-than-average since the early 2000s. Last winter was a bit above average but the previous season was way below-average.
How do we make these forecasts?
Seasonal forecasts are much different than your standard 7-day forecast you see on TV or get on a mobile app. I can't tell you if it will snow on January 23rd or be mild on December 17th. Seasonal forecasts deal with broad patterns, both over the United States and globally. Forecasters look at what's going on with water temperatures in the oceans, what winds in the stratosphere are doing, what the rate of increasing snow cover over Siberia is and much more. We truly look globally. After assessing these things, we look back at previous years that had similar conditions. These are called "analogs". We determine what type of winter season unfolded in those years under those conditions and then see how likely it is that this winter will play out in a similar fashion.Additionally, we have climate models that provide temperature and precipitation forecasts over several months. These models, just like the models we use to help us make a 7-day forecast, have their strengths and weaknesses and the forecaster must know how to use them correctly. Think of a weather computer model like a hammer. It's a tool that requires a qualified human to use it correctly. The hammer will not build a house on it's own and is also fairly useless in the hands of someone who isn't skilled at using it.Lastly, experience and intuition. Learning from past mistakes is very important in all walks of life and that includes weather forecasting...whether it's a 3-hour forecast or a 3-month forecast.
[wpvideo 8aShURbO]La Nina! What is it? Put simply, it's the cooling of the waters in the equatorial Pacific Ocean, near South America. Why do we care about that?? What does it have to do with our weather in Ohio and Pennsylvania?The oceans and atmosphere play in the same sandbox known as our planet. The atmosphere can react to changes in the ocean (and vice versa). Whenever this part of the Pacific cools (or warms, the "El Nino" phase) the steering currents in the atmosphere, or jet stream, can be altered. Often (but not always!) La Nina results in a stormy pattern over the Pacific Northwest and the Ohio Valley during the cold season. The stronger the La Nina (or El Nino), the more pronounced (and easier to predict) the affects typically are over the United States.Current water temperature anomalies: We also take note of pools of cool and warm water in other places, such as near Australia, the northern Pacific and near the east and west coasts of the United States.
The what? The quasi-biennial oscillation is important and the fact that it did not behave as expected likely contributed largely to last winter's warmth (and so-so forecasts). Have a look:[wpvideo kMeHfAXz]
This Year's Analogs
There are other years I could include in this list but these are probably the best matches. What do they have in common? They were weak La Nina years and most were years with an easterly, or negative QBO. Most of these years did NOT have a warm November preceding winter, which we expect this year. (the exception? LAST November, which was warm. That's part of the reason last year is on the list despite having an opposite QBO signal)Notice most of the years on this list were modestly cold. Most had near to somewhat below average snow. Snow data for 1996-1997 is unavailable.When we throw all these years in the hopper and create an average, here's what the national temperature map looks like:
So based on the chilly-looking analogs, we should predict a slightly colder-than-average winter right?? Not so fast. Much of the modeling shows a warm winter. Now, I believe the modeling is too warm....but it can't be completely ignored. Here's generally what the models are showing:My forecast is, generally speaking a blend of the models and analogs, with more weight on the analogs. More on the forecast below.
I foresee a somewhat mild start to winter followed by more frequent arctic blasts in January. There will be loads of cold air in western and northern Canada to tap so any arctic intrusions, even if they are brief, could be powerful (even in a mild overall December). February could bring a less cold pattern and may shake out near average.Here's the map for the whole season. I'm expecting a 3-month departure from average of 0 to +2 degrees.
While I do expect PRECIPITATION to be above average this winter, SNOW should be pretty close to average. I expect a fair amount of "slop storms" that include chilly rains and mixed precipitation, especially in December.It's possible that March could be snowier-than-average again. But generally speaking I expect the snow to be divided up pretty close to climtalogical averages:
The Bottom Line
A winter that is not as mild as the last two but not as cold as 2013-2014 and 2014-2015. My confidence is higher than last year because of a somewhat stronger La Nina signal and a more "well behaved" QBO. Temperatures are tricky. More on that below.
What Could Go Wrong??
My confidence in the winter forecast is higher than last year but is not as high as two years ago when we have a raging El Nino. La Nina is still weak enough that other oscillations and factors can override it and dominate the pattern for stretches. These things are hard to predict more than a few weeks out.The models could be full of baloney with their warm look. The atmosphere seems to "want" to be warm over our region (this has been the case for 2+ years) and so it's hard to dismiss how warm the modeling is at this point.On the flip side, if the warm November that we expect is a harbinger of the winter pattern (like last year) then my forecast is not warm enough.Basically it comes down to this: My forecast is kind of in the middle of the warm models and cold-ish analogs. We should know more in a month, which is why:I'll have a full update December 1!