The Weather Pattern Continues To Repeat

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Thank you for stopping by the Weather Watch 12 blog!  If you are new to our interactive blog…welcome!  Each day we discuss a wide range of weather topics from the current days weather, to the big weather story across the U.S., or look ahead at the weather pattern.

A couple days ago one of our bloggers asked if I could discuss the weather pattern and what lies ahead.  So in today’s blog I will look back and ahead to let you know exactly what to expect coming up.

Making long range forecasts is risky business and never perfect, but a weather pattern theory known as the LRC allows for accurate long range weather forecasts to be made. LRC stands for Lezak’s Recurring Cycle.  I have been very excited to introduce this theory to viewers and bloggers here in Southeast Wisconsin.  I first learned about the theory 4 years ago while working in Kansas City. Here is what the theory states:

  • A unique weather pattern sets up every year between October 1st and November 10th
  • 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. Determining the cycle length each Fall really holds the key in using the LRC to forecast into the future. A very good idea of the cycle length is usually determined anywhere from late November thru December. Once the pattern goes thru its second cycle a period of days can be placed on the cycle length. As I have mentioned in previous blog entries, the cycle length this year is about 60-62 days.

When doing a map comparison to show a previous part of the cycle to the current weather I will use 500mb maps.  A 500mb map is basically the middle of the atmosphere.  This part of the atmosphere is a good areas to pick up on the long wave pattern across the U.S.  It also eliminates surfaces effects such as friction and microclimates.  In other words this helps to focus on the overall pattern.

Let’s start by looking back to November 21 and the pattern on that date.  Below is an archived 500mb map showing many features(click on the map to enlarge).  I labeled parts of the map 1-4 to highlight areas to compare on the next map.  #1 is a compact upper low around Nova Scotia in Canada…while #2 is an upper low over the southern Plains.  #3 is a weaker trough over Canada, and #4 is a trough digging into the Western U.S.

Now according to the theory, the overall weather pattern and same general flow should exist roughly 120 days or so later…or two cycle periods.

Let’s look at the latest 500mb forecast map for March 25.  I again labeled 1-4 on the map below to correspond with what I am comparing the feature to on the map above from November 21. 

Numbers 1 and 2 are almost spot on matches to the features from November 21.  For number 3 and 4 the troughs exist, but slight position and strength differences are present, but the overall pattern is the same.  The trough near the Pacific Northwest Coast for March 25 is a little farther west than the one in November.  This slight shift and the presence of a ridge just to its east near the northern Rockies is allowing the upper low/trough over Canada to dive farthern south. 

This is just one example of the LRC, and an example of where the pattern is currently at.  Remember, the more ‘active’ months for Milwaukee and Southeast Wisconsin in terms of precipitation and temperature swings have occurred in October, December, and February.  With a roughly 60ish day cycle present…this means April will be more active and present more rain and maybe snow chances for the area compared to March.  Coming up soon I will issue a forecast for April & May!

In the meantime, please take our poll question.  The LRC is a theory(not proven yet) that states the weather pattern repeats.  What to you think?

Have a great day and make sure to post your thoughts or questions to the comments section!

Jeremy Nelson

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6 Responses

  1. I think in terms of the general weather pattern repeating, I’d say that yes there does seem to be something to the LRC. However, in terms of actually being able to predict our weather weeks in advance, I’m not so sure of that.

    I think of that storm in late February that was supposed to be a very wet storm and it ended up just swiping us instead and now this month seems to be all about getting glancing blows or just missing out on systems that previously hit us much harder in previous cycles. The theory is probably the best way to go when long range forecasting, but I believe its results are still far from a sure thing.

    • Daniel,

      Thanks for your take. A couple of things to keep in mind. The LRC is used to forecast the long term long wave ridges and troughs. This is best seen at the 500mb level…not at the surface. At the surface the amount of moisture, temperature, etc. are all variables that if they change slightly will have a large impact on the overall result of the storm at the surface. Also, microscale and mesoscale occurrances can not be determined by the LRC. An example is lake effect snow. A northeast wind versus a north wind can be the difference between no snow and several inches of snow…which we saw in February.

      Also a big factor is the seasonal shift of the jet stream. In the middle of winter it will be stronger and likely farther south versus its position in the Fall or Spring. This also leads to the slightly different storm positions that you referred to. That is why now I am comparing our March pattern back to November…the jet stream position is closer to that versus this pattern in January.

      Finally, I look at it like this…the overall pattern was repeating this winter. That is why the mid-Atlantic had record snow and now a couple good rains, and Kansas City saw one of its snowiest winters ever. The long term long wave ridges and troughs get locked into a favored position, and then when storms develop they often track in the same general areas.

      Hopefully this helps a little in regards to your question.

      • “Also, microscale and mesoscale occurrances can not be determined by the LRC. ”

        I think it can. I think even mesoscale behaviors carry a memory based on the synoptic pattern. That said, to be able to tune in close enough to pick it up can be very difficult as it is very subtle and often buried in noise of other factors such as friction and other microclimate effects.

        Believing that all the different scales are interrelated, I can’t see how the LRC could be valid in only one level and not the others.

      • I have said before that all level are related, but to best see the overall pattern just looking at the surface by itself is very difficult. Keep in mind that around Milwaukee Lake Michigan has a big effect on the weather from lake effect snow to temperatures. Also, the water temperature of the lake will play a role in the weather.

        Over the past several months I think the many ‘hits’ from the long range forecasts that we have provided are a good example of how the pattern at 500mb can be translated down to the surface.

        Jeremy

  2. Jeremy, spot on. I remember January was cold and quiet for the most part. March has been fairly quiet and warm (difference in jet stream position?). Hopefully April will bring rain instead of snow. I am all for snow Nov-early March, but April ehh.

    • Bryan,

      January was 1.7 degrees above average for temps…precipitation was below average. The snow total in January was mainly from 1 snow and that was about 50% lake effect.

      Thanks for reading! Jeremy

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