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Thank you for reading the Weather Watch 12 blog. Each day we strive to teach you something new and exciting weather related. In today’s entry, I will go over why the wet days expected the final 8-9 days of April are tied to the weather that occurred back in October, December, and February!
When I started at WISN back in December I have been providing long range forecasts exclusively in our blog. The long range forecasts that I make are based based on the LRC(Lezak’s Recurring Cycle), which is a weather pattern theory that I learned about while working in Kansas City. If you are new to the blog or just need a quick refresher…
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/spring/early summer-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.
As I have mentioned many times, this year’s cycling weather pattern is on roughly a 60-62 day cycle. The best way to see the large scale pattern is by looking at the middle of the atmosphere, or the 500mb level on a map. Below is a map comparison…first I will show the map for this coming Saturday, and then the archived map from 3 cycle periods ago in October.
Below is the 12Z GFS forecast 500mb map for this Saturday. Notice the large upper low over the central Plains.
The LRC says that the weather pattern repeats or cycles, so let’s look back 3 cycle periods to October. The map below is an archived 500mb map from October 22. Notice the large upper low over the central Plains.
I find it amazing that each time through the cyle, these same large scale features continue to repeat! Here are some questions you may know be asking:
So what about the other 2 cycles in December and February? And what were the results near the surface where we live? Also, was this information ever posted in a forecast saying that April would end wet? Let’s answer those questions.
In the long range April forecast that was issued in late March, I said the final 8-9 days of April would be wet, with some areas picking up 2″ of rain in this timeframe. Let’s look back at the surface results from the previous 3 cycles that correspond to roughly April 20-30 here in Milwaukee.
- Rain recorded on all days but 1
- Rain total in this period: 2.85″
- Rain or snow recorded on all days
- Precipitation in this period: 1.70″
- Snow total: 6.8″
- Rain or snow recorded on all days but 1
- Precipitation total during period: 0.34″
- Snow total: 5.4″
After looking at the data above, and the pattern moving forward, this is why I am confident and was confident a month ago that the final days of April would be wet in Southeast Wisconsin. This certainly comes as good news since we need the moisture, our 2010 precipitation totals is about 4.50″ below average!
If you have any questions about the weather pattern or what’s ahead for the weekend, just leave your questions and thoughts in the interactive comments section of the blog! Also, make sure to join us on Facebook at WeatherWatch 12
Have a great day!