Winter Forecast 2010-2011

The most common question that I receive has to be, “What will this winter be like?”.

We will answer that question by using a relatively new weather pattern theory that can help in forecasting our weather out weeks, or months in advance! Let’s start with an introduction to the theory, and then get into this year’s winter forecast!

Back in 2006 I started working at a tv station in Kansas City. The Chief Meteorologist at my station was Gary Lezak. When I started he introduced me to a weather pattern theory he discovered years ago. Once the theory was first explained to me I was the biggest skeptic since it sounded too good to be true and really unbelievable. I was told to follow along for a year, learn, and then form my opinion. I agreed since I was really more curious than anything. After just 3-6 months of watching and studying the pattern, it became very clear that there really was something to this theory.

Back in 2006 the theory was not named, today it is called the ‘LRC’ which stands for Lezak’s Recurring Cycle. Here is what the theory states:

• A unique weather pattern sets up every year between October 1^st and November 10^th
• The weather pattern cycles, repeats, and continues through winter, spring and into summer. Identifying the cycle length helps tremendously when making long range weather predictions.
• Long term long-wave troughs and ridges become established and also repeat at regular times within the cycle. These dominant repeating features are a clue to where storm systems will reach peak strength, and where they will be their weakest.
• The LRC is a winter-long pattern! There is a pattern! It isn’t just one long-wave trough, storm system, or ridge. It is a sequence of troughs and ridges that are cycling across the Northern Hemisphere.

To put this in very simple terms, the weather pattern that occurs in October and November repeats thru the Winter, Spring, and into the Summer. The cycle length will vary each year. I’ve seen cycles of 42-46 days, 60-62 days, etc. The easiest way to view the LRC is to look at maps in the middle of the atmosphere, the 500mb level. The 500mb level is really a good spot to analyze the trough(lows) and ridge(highs) positions to help determine the long term longwave ridges and troughs. At the 500mb level you also don’t have to factor in friction or surface moisture. The theory can be translated down to the surface(where we live), which we do in the winter forecast.

After studying this Fall’s overall weather pattern, analyzing countless 500mb maps, and picking out where ridges and troughs reach peak intensity, we were able to put together a comprehensive look at this winter.

A way I like to explain this is to think of a roulette wheel. Once the weather pattern begins to form in early October the wheel begins to spin and the ball is dropped. At this point there is an equal chance of all types of weather, as the pattern is just forming. Once we get to mid-November the ball lands, and our pattern is set and begins to cycle. Where the ball is going to land each year is an unknown. Will it land on a mild and dry winter, how about cold and snowy, or warm and wet?

Let’s start by looking at some of the key features to this year’s pattern. I believe there are 2 dominant features that will drive our weather not only this winter, but through spring and into summer!

Feature #1

The first and likely strongest feature, is a ‘long term’ long-wave trough stretching from Hudson Bay through the Ohio Valley. When this part of the pattern occurs, it will favor fast moving ‘clipper’ systems that will race by bringing Wisconsin light precipitation and shots of frigid arctic air. The cold combined with a northeast wind on the backside of the lows, should give lakeshore areas several chances for quick bursts of lake effect snow. Click to enlarge the map.

This part of the pattern has already occurred in our area. The dominant trough feature showed up on the 500mb map back on November 5 shown below, and other times when we studied the pattern from October into November. This is a feature we expect to see many more times as the pattern repeats.

Feature #2

The second feature produced the massive wind storm that blew through back on October 26. While another storm of that magnitude is unlikely, the position of the ‘long term’ long-wave trough over the Plains and Midwest will support the possibility of stronger and wetter storms. This part of the pattern could bring Wisconsin several chances of precipitation each time through the cycle as storm systems fall into this favored long wave position. This part of the pattern should produce several opportunities for major winter storms!

This feature was revealed during the week of October 26 when a storm system with a record low central pressure slid just to the west of Wisconsin. The result was a major storm, with severe weather, rain, and high winds. As this part of the pattern repeats, I again expect active weather with all types of precipitation possible. The map below is a 500mb chart from October 26 of this year.

As the pattern cycles, there will be other smaller, less dominant features that will provide us our daily weather, but even those are all part of the same cycle.

When putting this forecast together, I also looked at historical data on La Nina winters in Wisconsin, because this will be a La Nina winter. The last La Nina winter was in 2007-08, when Milwaukee picked up nearly 100″ of snow!

La Nina is the cooling of the equatorial Pacific waters. Below is a sea surface temperature and anomaly map from the NCEP site from November 22. This shows the cooler than average waters near the equator in the Pacific Ocean.

While I do believe there may be a La Nina influence to our weather this winter, I firmly believe that the overall weather pattern and cycling of it play a much bigger role than La Nina or El Nino.

Below are snow totals for La Nina winters in Milwaukee. Keep in mind that Milwaukee averages 52.4″ of snow in a typical winter. For our area, La Nina winters have historically produced above average snowfall.  But in the past 60 years, only 6 of 11 La Nina episodes have produced winters with above average snow!

• 2007-08 99.1″
• 2000-01 59.3″
• 1998-99 60.7″
• 1995-96 51.5″
• 1988-89 39.9″
• 1975-76 45.2″
• 1973-74 83.2″
• 1970-71 57.3″
• 1964-65 74.0″
• 1954-55 39.2″
• 1949-50 45.2″

After everything we discussed in regards to the LRC, dominant ‘long term’ long-waves, the cycling pattern, and a possible La Nina influence…Here is what we are expecting for temperatures and snowfall this winter!

Temperatures

• Near Average
• Multiple below zero readings, something Milwaukee did not record once last winter!
• A good chance of at least one month having below average temperatures

Snowfall

• 50 to 60 inches across southeastern Wisconsin
• 10 to 20 inches more than last winter

Right now the cycle duration(number of days) is still a bit up in the air. Typically we can pin down the cycle length in December. Meaning we should have a very good idea in the next 2 weeks. At this early stage the cycle duration is likely somewhere between 37-45 days. Again, I will narrow this number down in the coming weeks, and begin to make more specific forecasts of when storms may hit our area…weeks in advance!

There are many more aspects to the theory that I’m sure I left out, but that is why this blog is interactive, so you can ask questions and follow along with us. Please feel free to share your thoughts and questions, and I will do my best to provide an answer.

This theory was recently presented at the American Meteorological Society conference, and research continues into proving the theory. While the theory is not perfect, it is the best way I know of to provide accurate long range forecasts weeks, or even months in advance!

I hope you enjoyed the winter forecast!

Jeremy Nelson