Monday, November 7, 2016

Winter Forecast 2016-17

Thanks for coming by the blog and spending some time reading my thoughts on what I think will happen this winter. Let me just say here at the start that seasonal forecasts are difficult. Some meteorologists shy away from making them because they require a lot of time and effort. There's a TON of data to look at and so many things to consider. I truly enjoy coming up with a winter forecast, because after all, it's the most common asked question from August 1st through about December 31st.

I'll share my forecast and thoughts, and if you are still interested in how I came to these conclusions, feel free to keep on reading.

I expect this will be a typical Kansas winter with several (could be as many as 4-6) big surges of cold air riding down the east side of the Rockies. We often refer to these as Arctic outbreaks. I'm also expecting that we will end up with near normal snowfall for much of the state. That would be roughly 10-15 inches of snow across central and eastern Kansas, and slightly higher amounts the farther west you go (could be 20-30 inches). For those who hate winter altogether, we will have some milder weather mixed in from time to time, but they may be brief.
  • Normal snowfall for Wichita is about 15 inches. It's closer to 40 inches around Goodland and Colby. So there is quite a range from one part of the state to the next.
One thing most of us can agree on is that we didn't really have a winter last year. One of the biggest snow events of the year came Easter morning, but that melted in a hurry. Dodge City only had about 10 inches of snow last winter. You might remember all of the talk about a STRONG El Nino. It was almost the strongest one on record, but came up a little short. There was tremendous moisture across the south. So many states in the south had record flooding, including Texas, Louisiana, even southern Oklahoma had a lot of rain in the winter. Our temperatures in Kansas were very mild.

So here's what's going on for this winter:
El Nino/La Nina:
El Nino died back in the early summer months and we've been watching a very slow, La Nina coming on in the Pacific. I'm not going to go into a ton of detail about La Nina other than to show a map and simply state that it's likely to be weak at best this winter. And the forecasts show it might even fade away into spring of 2017. We can't base our forecast solely on this factor, which is what too many long range forecasts are doing. There isn't much correlation between La Nina and how much snow we tend to get.

Arctic Oscillation:
One of the indicators tipping the scale toward the colder in my winter forecast is that the Arctic Oscillation (AO) has been negative for quite some time and is likely to stay negative for much of the winter season. Why is this important? While it's not a guarantee, when the AO goes negative, the jet stream circulating counterclockwise near the Arctic weakens and allows much colder air to drop farther south across the US. Last year, we had a positive AO much of the winter (see image below)

AO for the next few weeks....looking negative for the end of the month

North Atlantic Oscillation:
This particular index is focused more over Iceland and the eastern Atlantic Ocean. Again, it gives us an indication of jet stream patterns and where highs and lows are focused. It is more of an indicator of patterns impacting the eastern US, but atlas, if we can understand patterns east of us, we can sometimes unlock clues for Kansas weather too. It's forecast to be negative most of the winter as well, which indicates cold air building up over Canada and a much better chance it can dive south. 

Build up of cold air/snow in Siberia:
There is recent evidence to suggest that a above normal snowfall and much colder air in Siberia (in early fall) can give some confidence as to what happens across North America. If you take a look at the map, there is tremendous cold air (well below normal) and snow, which helps boost the confidence in the cold outbreaks that we will see this winter around here.

Pacific Decadal Oscillation (PDO):
This tells us what the water temperatures are like in the North Pacific and along the west coast of the United States. It has some similarities to El Nino/La Nina, but what is different is how long it lasts. El Nino might last months, but the different phases of the PDO can last years. The latest PDO has been slightly warm, which indicate the possibility of a milder winter.

Please feel free to ask questions. There is so much more than what I posted here, but as we go through the next few weeks, I'll be adding additional thoughts and maps of course. 

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