The Weather Pattern Repeats…Again

***Watch WISN 12 News at 5, 6, & 10pm for Milwaukee’s most accurate forecast!***

Thank you for reading the Weather Watch 12 blog!  The warm weather is still on track to arrive in full force on Wednesday and Thursday with highs in the 60s and 70s.

Last Thursday we were the first station in town to begin talking about and forecasting highs in the 70s.  I was confident of a big warm-up based on the weather pattern that was going to arrive this week.  If you are new to the blog, or just need a quick refresher, I use a weather pattern theory called the LRC to help in making long range forecasts.  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-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. Determining the cycle length each Fall really holds the key in using the LRC to forecast into the future. A very good idea of the cycle length is usually determined anywhere from late November thru December. Once the pattern goes thru its second cycle a period of days can be placed on the cycle length. As I have mentioned in previous blog entries, the cycle length this year is about 60-62 days.

In Wednesday’s blog I will issue a forecast for April and May based on this theory.  The forecast will be for all of Southeast Wisconsin.

Now back to the warm-up this week and how it relates to the previous cycles in this year’s weather pattern.  Let’s look back to late November…about 120 days ago or two cycle periods and compare to our current pattern.

The best way to see the long term long wave ridges and troughs is to look at the 500mb level…which is roughly in the middle of the atmosphere.  I will label 4 numbers on each map so that you can see the same pattern exists.

Below is the 500mb archived map from November 28.  The key feature here is the large ridge over the central U.S. labeled #4. 

Now fast forwarding about 120 days or two cycle periods we arrive at our warm-up for this week.  I was even shocked when I looked at the comparison to what is about to happen!  Below is the 6Z GFS 500mp forecast map for late Wednesday.  I labeled numbers 1-4 to match with the features that I believe correspond to the map above.

Again, #4 which is a large ridge over the Mississippi Valley region is the key to our big warm-up.  The storm or trough out west labeled #3 will eventually bring us a chance of showers and thunderstorms heading into this weekend.  This same pattern also occurred around January 26-27.  Remember, the more active months of weather for Milwaukee have been October, December, and February.  This should mean a more active weather pattern may be just around the corner.

Some wilder weather may be in our near future.  I will discuss this and look at April and May as a whole in tomorrow’s blog.  Until then…enjoy the 50s for today…and 60s on Wednesday.  And if the high clouds stay away…70s on Thursday!

If you have any questions about the weather pattern or thoughts about the weather please leave them in the comments section of the blog!

Have a great day!

Jeremy Nelson

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6 Responses

  1. Thanks for the blog, I enjoy reading and learn a lot. Are we going to lose the cloud cover? It has been cloudy here all day and has kept our temps down.

    • Lots of cirrostratus clouds around today. Temps are still around 60 inland and Milwaukee topped out at 57 so far. We’ll likely see some high clouds the next few days, but low 70s still look good on Thursday.

      Jeremy

  2. Hey Jeremy, we’re going to keep our warm weather down here in KC as long as we can because you gave us your ridiculously cold weather and snow. 😛

    • At least we should be in the 70s by Thursday…that is 20-25 degrees above average around here. You had a tough winter…you deserve the warm-up:) Thanks for stopping by!

      Jeremy

  3. Nice pattern match. I again find myself watching the AO trend and the equatorial Pacific. While the conus 500mb pattern matches have been spot on this year, I am blown away by the behavior/parallels between the other climate oscillations.

    It has been impressive. Charting the teleconnections has yielded what looks like an EKG – cycling very consistently ~60 days.

    What a year for a case study!

  4. Also, in looking at April, October looks fairly good so far. Looks like the Greenland blocking may be returning again and wants to push the polar vortex south. I wonder how far west it will reach. Milwaukee may be on the very west side of the cool air spilling in. Will be fun to watch.

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