More Active Pattern Ahead?

***Watch WISN 12 News for the latest weather information!***

Thank you for stopping by the Weather Watch 12 blog!  After a relatively quiet first week of January in the books, signs of a much more active pattern are beginning to show.

The more active pattern should lead to several chances for precipitation, including some ‘wetter’ storms and also shots of frigid arctic air!  If you are new to the blog or just need a quick refresher, I base my long range forecasts and trends off a weather pattern theory called the LRC, or Lezak’s Recurring Cycle.

Here are the basics of the theory:

  • 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. I’ve seen cycles of 42-46 days, 60-62 days, etc.  This year’s cycle is around 46-52 days, but as of this writing the cycle duration has been hanging around 50 days for the past few weeks.

The quick moving clipper systems and shots of light snow that we have experienced this week were a highlight of this year’s pattern identified in the winter forecast.  Below is the map that I showed back on November 23.  The trough in the Great Lakes to the Ohio Valley is one of the main long term longwaves in this year’s cycling pattern.

To some, this may be the ‘boring’ part of the pattern.  A northwest flow generally brings lighter snows and doses of cold air.  But a pattern shift is ahead, and that should lead to more active weather.

As the pattern shifts, a transition to more of a southwest flow will occur.  This will allow more moisture to work into the systems as they move into the central U.S.  As the storms move by, the flood gates may open up allowing very cold air to spill into the Midwest.

Below is the map that I showed in the winter forecast highlighting the long term longwave that will likely bring us a majority of our precipitation this winter.  Remember Minneapolis had a record setting snowy December?  This year’s LRC has Minneapolis in a prime location for snow.

While southeastern Wisconsin is not in the bullseye this winter, I do expect to see more good snow opportunities as the active part of the pattern returns beginning this week.

Another indicator that a more active pattern may be right around the corner is looking at the arctic oscillation.  Here is a quick explainer of the ‘AO’.

The Arctic Oscillation

The Arctic Oscillation refers to opposing atmospheric pressure patterns in northern middle and high latitudes.

The oscillation exhibits a “negative phase” with relatively high pressure over the polar region and low pressure at midlatitudes (about 45 degrees North), and a “positive phase” in which the pattern is reversed. In the positive phase, higher pressure at midlatitudes drives ocean storms farther north, and changes in the circulation pattern bring wetter weather to Alaska, Scotland and Scandinavia, as well as drier conditions to the western United States and the Mediterranean. In the positive phase, frigid winter air does not extend as far into the middle of North America as it would during the negative phase of the oscillation. This keeps much of the United States east of the Rocky Mountains warmer than normal, but leaves Greenland and Newfoundland colder than usual.

 

Now that you know what the AO is, let’s look at whether we are in a positive or negative phase.  Since December 16 the AO has been negative, but around Christmas it became a little less negative.  But heading into next week, the AO is forecast is become more negative again.

Many of the dips in the AO observed data below were accompanied by ‘wettter’ periods.  Including November 21-25, which moving that forward 50 days(current cycle duration) leads us to this coming week! 

 

So by using the LRC and the arctic oscillation, I am confident that we are heading into a more active part of the pattern.  If you have questions about the pattern or this blog, just post your question to the comments section.

Make sure to watch WISN 12 News for the latest on the weekend.

Have a great day!

Jeremy

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17 Responses

  1. I wonder if this pattern coming up will yield our first sub zero low in almost two years. We’ve almost made it through half of the primary time frame where that usually happens (early December – end of February) and have been getting lucky so far.

    • Daniel,

      While there are no sure things in weather, I’m very confident we’ll drop below zero somewhere between January 14 and February 5. We just need a few inches of snow and one clear and calm night.

      Jeremy

  2. Interesting stuff, Jeremy! Sure hope you’re right 🙂

    Yeah, do you think we’ll have some sub-zeros coming up?

    Also, I’ve been watching the future computer models from the NWS (I’m an amateur!) and looking at the system for next weekend (the 15th) and it looks like the low passes through northern Wisconsin. Does this necessarily mean we’ll be on the warm end and have rain or a mix (assuming the low stays there) or is it likely that we’d be all snow? I also notice that another low appears to form to the south. Do you think these two would combine?

    Dan K.

    • Dan,

      Outside of knowing there should be a storm around in that timeframe, the GFS that far out really can’t be trusted. If we have enough cold air in place I don’t think precipitation type should be an issue. The 14th-15th will be fun to watch, but this Tuesday looks interesting, especially because there may be some lake effect.

      Jeremy

  3. Cool, thanks for the info…. You guys are awesome, and this is the only blog I ever follow!

    Are there any other resources I can use like the GFS that can predict future storms?

    • GFS, European, and Canadian models all forecast out pretty far, about 7-10 days in most cases. Thanks for reading the blog!

      Jeremy

  4. Cool, thanks much!

  5. Should anyone be interested, a bit more about the AO and the LRC. http://tinyurl.com/25qm96p

  6. Jeremy,

    I’m certainly hoping for at least one or two true blizzards/ major winter storms this year. It’s been a pretty quiet winter so far in SE Wisconsin.

    I was wondering if I could use a couple of the graphics in your blog for my amateur weather forecasting blog? I would, of course, give credit.

    • Chris,

      Feel free to use any of the graphics, and thank you for crediting them. While I always say the long range GFS needs to be taken with a grain of salt. It is showing a very active pattern over the next couple of weeks, and yes I do believe the active part. The question will be where do the storms track and where will the heaviest snow/precip. line up. Our first chance of snow comes in likely on Tuesday. Monday may bring some light lake effect in spots, but that will be a day of call I’m guessing as to if/where that sets up.

      Jeremy

  7. Great job as always. Thanks Jeremy. The info you and Gary Lezak have shown on the AO is very interesting. So much to learn 🙂

    • Steven,

      By using the LRC and other teleconnections together making long range forecasts can be somewhat ‘easy’:) I still have lots to learn and each year/pattern is unique. Gary was a fantastic teacher that taught me a lot about the LRC. I still talk to him each week and continue to learn more so that I can share it with others.

      Jeremy

  8. […] great way to learn the LRC is to follow the WeatherWatch 12 blog. Jeremy Nelson is a student of the LRC and is great at explaining it and answering questions that […]

  9. Jeremy, you sure made it easy for me to obtain information on other circulations. With being on a start-up this past week and now finally having time to surf, running across this entry saved a few extra clicks. Thanks! I have a couple friends that are teachers in the area who know about my ‘backyard snowfall forecast’ using the LRC via my wife. As it turns out, the big one at the end of the month falls during the school week. These friends are now excited that there may be a snow day in their future. However, with the cycle shifting to a 50 day cycle vs a 47 day cycle about a month ago when I made the forecast, I am almost afraid to tell them that the storm may occur over the weekend now. haha. Hopefully the big snows, if they come, occur on a Friday or Monday so they get at least one snow day! 🙂

    Looking forward to the active pattern and a HUGE Packer victory tomorrow!

    • Josh,

      With the LRC it is good to always view the cycle as a range of days. I’ve always done this in the past, and my entry on the 15th of December focused too much on the 47 day cycle. As in past year’s, the cycle truly revealed itself around Christmas.

      I’m looking forward to the end of the month too!

      Jeremy

  10. Hi, Jeremy!

    Thanks for being our teacher! I have really come to learn alot from you and Mark about the weather patterns. Good to know that some snow is in the offing. As part of the overall LRC, you’ve made mention of the October “signature storm” that returned on December 11/12 making another return around the end of January. But in some recent posts made by others about that storm’s reappearance, there was a lot of backing away from that storm being another blizzard as it was in December — or even being a snowmaker at all. At this point in time, what’s your take on the make-up of that signature storm?

    Don in Reeseville — Dodge County

    • Don,

      A few things. I still expect the storm to return around the end of the month. In my opinion this is probably the easiest feature of the cycle to pick out. From the very strong jet stream to the deep lows at the surface. With that said, we can’t expect the storm to produce record pressure readings, snow, temperatures, ect. each time it returns. Whenever this storm returns, seasonal effects such as moisture, jet stream location/strength can vary. So to say there will be a blizzard or heavy snow at this point is a very tough call. I do think it is likely this will produce another major storm. But exact location/track and available moisture and temperature profile are surface features that will be ironed out as the storm nears hours or days out.

      Keep in mind the LRC views the overall large scale pattern, and then we try to use this info to forecast at the surface. Tricky, but fun!

      Hopefully this helps, but if you have more questions just ask.

      Jeremy

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