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Thank you for stopping by the Weather Watch 12 blog. In today’s blog we are going to focus our attention on the hot weather expected for Memorial Day. The first 90 degree high of the season in Milwaukee isn’t out of the question on Monday, and this possibility was forecast a month ago…no seriously it was!
If you follow the blog, you know we use a weather pattern theory called the LRC, or Lezak’s Recurring Cycle to make accurate long range weather forecasts. Here is part of the May-July long range forecast that was posted here in the blog back on April 30.
‘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.’
But did you know the part of the weather pattern that will produce the hot temperatures on Monday has occurred four times already? The basics of the theory that allows us to make long range forecasts are highlighted below.
- 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 season 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.
Let’s take a look at past parts of the pattern, and how using them led to the hot Memorial Day forecast a month in advance. The first time this feature revealed itself was during the second week of November. On November 11 the high temperature in Milwaukee was 65…17 degrees above average. Here is the 500mb(middle of the atmosphere) map from that day.
The key feature is the strong southwest flow aloft over Wisconsin, and the trough in the Rockies. These features would begin to repeat roughly every 50 days, the length of this LRC season’s cycle duration.
The second time through the cycle it was the holiday season. But this part of the pattern warmed us up just in time to ring in 2011. On December 31 the high temperature in Milwaukee was 54…25 degrees above average. The same strong Rockies trough and southwest flow in the Midwest returned. Here is the 500mb map from December 31.
Roughly 50 days after this another big warm-up arrived in February. 50 days(or 1 cycle later) after that, southeast Wisconsin’s first taste of summer arrived as the pattern repeated again! On April 10, highs soared into the 80s! Milwaukee hit 84…32 degrees above average!
The trough in the Rockies and strong southwest flow returned. Here is the 500mb map from April 10.
It’s amazing how the features fall into the same general location each time through the cycle. Once the April 10 warm-up occurred, I set my sights on the next time through the cycle. It just so happens that 50 days after April 10 was Memorial Day. So by using the LRC, I made sure to highlight May 30-31 as the potential first 90 degree high of the season in Milwaukee. A high of 90 on Memorial day would be 19 degrees above average.
By using the LRC, and also shorter range models in the past week, you may have noticed that our forecast for Memorial Day has been much warmer than other forecasts…now you know why.
Let’s end by looking at the 500mb forecast map for this Monday from the GFS computer model. The trough in the Rockies and strong southwest flow are present, and another big warm-up is likely!
I’ve used the LRC for 5 years now, and while I expect the features to repeat, it still even amazes me! If you would like to view the entire long range forecast that was posted here in the blog back on April 30, just click below.
If you have questions about the LRC or the weather pattern, just leave your thoughts and questions in the comments section of the blog.
In the meantime, make sure to check out WISN 12 News for the latest on rain chances for Sunday. And if you want to track rain from your home or on the go, just click on the interactive radar link.
Have a happy and safe holiday weekend!