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