May & Summer Forecast Based on Lezak’s Recurring Cycle

Thank you for stopping by the Weather Watch 12 blog!  Late spring and summer, the peak of severe weather season in Wisconsin, and it is almost here.  In this entry we will discuss the long range forecast for May through August based on the LRC.  Included will be temperature and rainfall forecasts, along with date ranges when severe weather may be possible.

The ‘LRC’ which stands for Lezak’s Recurring Cycle is a weather pattern theory based on the following:

  • 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 summer.

The cycle length will vary each year. I’ve seen cycles of 42-46 days, 60-62 days, etc.  This year’s cycle duration is about 46-52 days.  Overall most of the weather events have repeated about 47-51 days apart.  After analyzing the pattern and surface results from October through April, I was able to get a very good idea of what should occur through summer.

The cycling weather pattern is about to repeat for the 5th time this LRC season!  For this forecast I will highlight the bigger features that should impact our weather over the next few months, and then give the forecast specific forecast for southeast Wisconsin.

Let’s get started by highlighting the two key features of the pattern.  The ‘signature’ storm has produced every time in the cycle for southeast Wisconsin, and it should return soon. 

  • October 26-27  Strong winds and severe weather
  • December 11-12  Heavy rain and snow
  • February 1-2  Massive blizzard
  • March 22-23  Rain in Milwaukee, 17.8″ snow in Green Bay

Here is the 500mb(middle of the atmosphere) map from the last time the ‘signature’ storm hit the area on March 23, 2011. 

500mb March 23, 2011

This part of the pattern should return between May 9-13.  For our area we’ll watch out for rain and the possibility of severe weather.

The weather pattern begins to fade as the summer progresses, but I think a final ‘signature’ storm could arrive around June 29-July 2.  This would fall very close to the start of the 4th of July holiday weekend!

Another feature that has occurred numerous times is the ‘big warm-up’ part of the pattern.  Each time through the cycle much above average temperatures have been experienced for at least 1-3 days.  This part of the pattern occurred around November 10-12, December 30-January 1, February 16-18, and then most recently April 9-11.

Below is the 500mb map from April 10, 2011.  This shows a southwest flow aloft bringing warm, moist air into the region, and also an upper low over the Rockies. 

500mb April 10, 2011

On April 10, Milwakee reached a high of 84 degrees and there were 14 tornadoes reported around the state.

This part of the pattern should return around May 29-31(Memorial Day).  I do expect another big warm-up, and severe weather could accompany the storm system.  If the pattern holds together into later July, this feature may return one final time to Wisconsin around July 19.

The ‘signature’ storm and the ‘big warm-up’ parts of the pattern may return two more times each.  There will also be other highlights mixed in over the next several months.  Here is the entire long range forecast with a discussion included.

————————————————————————————-

Temperatures

  • Below average
  • Less than 11 – 90 degree days in Milwaukee

Discussion:  Average monthly temperatures have been below average for the past 5 months.  Only about 1 degree below average, but this trend will be tough to break.  Last summer we had a number of above average months going into summer, and that result continued.  So for the next several months I expect the average monthly temperature to remain below average. 

If cold air spills in on the backside of the May ‘signature’ storm like it did in March, the potential for a late season frost can’t be ruled out.  IF that was to occur the possible date ranges would be May 13-18.  This time of year the coldest overnight readings generally occur inland on clear, calm nights.

In looking at the overall pattern I think the hottest temperature in Milwaukee will be 93 degrees.  That would likely occur with one of the bigger features in the pattern.  With that said I think the first chance at 90 degrees would come around May 30-31.  Then, if the pattern holds together another run to possibly the warmest temperature of the summer around July 19. 

Rainfall

  • Above average
  • One month of 6″+ possible

Discussion:  April may have been a good preview of how active parts of the summer may play out.  With nearly 6.00″ of rain in April in Milwaukee, I see more wet days in our future.  Extended periods of dry weather should be few and far between through July.  The most active part of the pattern will cycle back from very late May through June, and barring a freak event like last July 22, June may be the wettest month of the summer.

Possible Severe Weather Dates

  • May 9-13  ‘Signature’ storm
  • May 29-31 ‘Big warm-up’ storm
  • June 7-9  Storm from November 22, April 19
  • June 29-July 2  ‘Signature’ storm
  • July 18-20  ‘Big warm-up’ storm

Discussion:  Without question predicting specifics with a severe weather event more than a couple of days out is nearly impossible.  What I’m showing here is when storm systems may return to our area, and ingredients could be in place for severe weather in the Midwest, including southern Wisconsin.  Obviously there will be severe weather that falls outside of these date ranges and I know that.  What I’m showing is when I think chances may be the highest based on the overall pattern. 

If you are curious, the massive tornado outbreak from this past week in the South produced severe weather in other parts of the pattern too in the South…back on November 29-30 and again on March 8-9.  I expect another round of severe weather from parts of the Plains to the Ohio Valley and maybe the South(kind of late in the season for severe weather there) around June 14-16.

—————————————————————————————

Now how does the long range forecast based on the LRC compare to the Climate Prediction Center’s seasonal outlook?  Below is the May-July temperature forecast, which calls for an increased chance of below average temperatures in the upper Midwest and Great Lakes. 

CPC Temperature Outlook 2011

Next is the May-July rainfall forecast, this also has southern Wisconsin in the above average area.

CPC Precipitation Summer Outlook

Typically the forecast based on the LRC differs from the CPC, but this time they actually fell in line with each other. 

I hope you enjoyed reading my thoughts on what’s ahead for the next several months.  Keep in mind the LRC weather pattern begins to fade as the summer progresses.  By August and September the transition period to next season’s pattern will begin, and by October and November a new pattern will reveal itself. 

Please add your thoughts and questions to the discussion in our interactive comments section.  And feel free to email this forecast to any family or friends.

Have a great day!

Jeremy Nelson

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17 Responses

  1. Thanks for the new outlook. I have been an avid fan of your blog. The Lezak’s recurring cycle has been fascinating to track. It really has proved to be a valuable tool to predict the weather. Thanks for introducing us to it.

    • Sue,

      Thanks for reading. I just don’t see us flipping a switch and a beautiful summer appears. With the knowledge of the LRC I’m confident in this forecast.

      Jeremy

  2. Interesting summer forecast. Signature storm for the first few days of Summerfest (June 29 -July 2)–could mean one or a few warm days and nights with a southwest wind keeping the lake breeze at bay, and, as you noted, possible severe weather.

    As warm as last summer was, by my count it only had 10 90 degree days. A better indicator of summer warmth might be the number of 80 degree days. Do you know the average number of 80 degree days in Milwaukee? By your forecast of below normal temperatures, we’ll likely hit 80 fewer than the usual number of days.

    I really appreciate this blog. Thanks for updating it daily.

    • Patrick,

      Yeah…80s can be pretty warm if it’s humid. But I’d guess the number of 80 degree days may be below average too. I’ll try to find that number, or if someone knows they can post it too.

      Great to have you participating in the blog.

      Jeremy

    • Patrick, I think a good indicator of ‘summer’ warmth is 80+ highs accompanied with 65+ mins. Not far off from your idea above. I like to call them ‘dog days’. Since 2007 I have kept track of such days in my backyard.

      http://www.theplayerstour.net/osnw3/x_summercomfort_dds.html

      Last year was a warm one. Granted my measuring instruments are not NWS certified as I use La Crosse technology versus Davis. But, it is a for what it’s worth project and I enjoy it. More comparisons of the few past summers in my backyard can be found by following the link below.

      http://osnw3.blogspot.com/2010/08/summer-is-in-books.html

      Jeremy, great breakdown and forecast using the LRC as always. As soon as I saw the CPC outlook I instantly thought that they had adopted using the LRC in their forecasts. Unlikely? No matter what, because of your tenacity in teaching the WeatherWatch 12 blog’s followers of the cycling patterns, SE WI and beyond are at the least one step ahead of the weatherwise person!

      • Josh,

        Thanks for sharing your data and numbers. The LRC exists, no question in my mind. The only question is when some solid research will be done. Until then, we will continue to teach anyone that wants to learn more right here in the blog.

        Jeremy

      • I enjoy sharing my data. I also understand that I am out of your forecast and viewing area so what I do share is usually of no interest for this blogs followers. But what the heck. I am about to start some ‘solid’ research in direction from Scott. Looking forward to share my results.

  3. Jeremy I find this theory fascinating. Despite the lower number of 80 and 90 degree days predicted, any thoughts on how humid or dry the summer might be? Will we have a cool dry pattern or will the higher than normal rainfall keep us humid?

    • Mike,

      I don’t see long dry stretches this summer. The longest dry spell in the last couple of months was 10 days back in March. Possible we could get a 7+ dry stretch with no rain, but I do think there will be enough systems moving through to bring rain when we need it this summer. Temperatures have only been slightly below normal the past 5 months, so if that holds true this summer we will still see plenty of 80 degree days, and I do expect some 90s too.

      As for humidity, if we are wet it may be higher, but if temperatures are a little lower it may be a little less noticeable. And so far this spring the high dew points have stayed away outside of April 10. Last spring we had warm weather a deal of the time, and that continued into summer.

      Jeremy

  4. hi jeremy , i got a question for you , When it the jet stream going to change and we start warming up ? It’s still cooler than it should be this time of year . When is the jet stream going to be above us , not below us ? I hope real soon !!!

    thanks chris

    • Chris,

      The LRC uses the position of the long term longwave ridges and troughs that set up last Fall. The overall position of those ridges and troughs still exist, and this is why the weather pattern has such a tough time changing. What happens is the storm systems want to fall into these long term longwave positions, and often reach peak strength there. With that said, we are stuck in the cooler part of the flow, and outside of blips of warm air here and there I don’t see a huge change coming our way.

      Typically the jet stream lifts north, closer to the U.S./Canadian border in summer, and I would say that is on average around June 1 in our area. But again, the jet stream position will flucuate throughout the summer, and it may be further south this year compared to last.

      Thanks for the question.

      Jeremy

  5. Sunday, May 1, 2011

    Haven’t had a rainfall amount or snow depth to report for a few days now. Things are starting to look up around here!

    Cordially,
    Tony (Pl. Prairie)

  6. Hi, Jeremy!!

    Thanks for the extended outlook for the rest of spring and summer. Lots to be paying attention to. I think I’ll print it out and study it over some more. I appreciate all the hard work you put into doing this for us.

    Wtih the ABC extended coverage of the taking out of Bin Laden, I missed your Sunday night late show {couldn’t stay awake past midnight}. Can you give us a quick heads up on the week ahead?

    Thanks!

    Don

    • Don,

      A chance of showers and t-storms on Saturday…I know that is a key day for you. Guessing it would not be an all day rain. Watch Mark at 5 & 6 for the latest on the weekend.

      Jeremy

      • Jeremy —

        Tell Mark to be very sure the chance for any kind of precip on Saturday is slim and none — 🙂

        If we end up with a wash out, can I interest you and the rest of the ch. 12 staff in a whole bunch of brats and burgers??? 🙂

        Don

  7. Nice write up and hopefully we do end up getting more comfortable days this time around in summer compared to last. So with the pattern breaking down later in summer, August could still end up being pretty hot and potentially dry as well. I’d be interested in knowing the average number of 80 degree days in a summer as well. Looking at stats over the last decade, I would imagine it is around 40… so I think we’re still in line for at least 30-35 this summer. Just trying to let the warm weather enthusiasts know there is some hope for them, although I’ll be wishing for otherwise.

    • Daniel,

      I’ll have to get the official number of 80 degree days for Milwaukee. August is a wild card, the pattern is faded or barely visible by then.

      Jeremy

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