Spring Flood Outlook & Active Weather Pattern Ahead

Thank you for stopping by the Weather Watch 12 blog.  The next two weeks will likely bring the Midwest several rounds of precipitation as a very active weather pattern takes hold.  With at least two ‘wetter’ systems on deck, the concerns for flooding in the Midwest are growing.

In this blog we’ll look at the current flood threat, and then use the LRC(Lezak’s Recurring Cycle) to pinpoint when some of the wetter storm systems will occur over the Midwest from now through April.

Let’s start with the Spring Flood Outlook.  This was released 2 weeks ago by the Hydrologic Information Center.  With record snows over parts of the upper Midwest this winter, it should come as no surprise that the highest threat for flooding is located over parts of Minnesota and the eastern Dakotas, and then along the Mississippi River south to St. Louis.

Spring Flood Outlook 2011

Here is why the National Weather Service is concerned about flooding in our part of the country.

Heavy late summer and autumn precipitation(twice the normal amount since October in parts of North Dakota and Minnesota) have left soils saturated and streams running high before the winter freeze-up.  NWS models show this year’s snowpack contains a water content ranked among the highest of the last 60 years.  The combination put a large portion of the North Central United States at risk of moderate to major flooding this spring, extending from northeastern Montana through western Wisconsin and along the Mississippi River south to St. Louis.

Since this map was published, the flood threat has also increased over parts of the eastern Midwest and Ohio Valley.

Now let’s use a weather pattern theory called the LRC, or Lezak’s Recurring Cycle to project forward and pinpoint when wet parts of the pattern will return from now through April over the Midwest.  If you are new to the blog or need a quick refresher, here are the basics of the LRC.

  • 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.

The cycle duration with this year’s pattern is roughly 46-52 days, but most events have consistently repeated around 50 days.  So the forecast made below will use roughly a 50 day cycle to project forward.

Let’s start with the rest of March, and again keep in mind this is for the Midwest!

——————————————————————————————————-

Rest of March 2011

March 8-9

A storm system will bring rain and snow to the Midwest.  This will be one of two potentially ‘wet’ storms that could produce 0.50″ or more of precipitation over a large part of the region.  Where colder air is in place, some 6″+ snow totals may occur.  This storm lines up most closely with a storm roughly 100 days ago, or 2 cyles.  That storm moved through around November 29-30.

March 11-12

This part of the pattern will drop a ‘clipper’ type system through the upper Midwest heading into the upcoming weekend.  This storm rolled through back on December 3-4, producing 6.1″ of snow in Minneapolis, and 3.6″ in Milwaukee.  It has repeated in each cycle, but I am referencing early December because I feel the jet stream position is most closely lined up with March.

Below is where the swath of precipitation(mostly snow) lined up in early December.

Precipitation December 3-4

Here is the where the 18Z GFS computer model is forecasting the swath coming up late this Friday into Saturday.  Pretty amazing, even more is the precipitation on both maps over Maine!

18Z GFS Precipitation March 12

This could be rain or snow, but parts of the upper Midwest will likely see several inchs of snow to start the weekend.

March 19-22

This is hands down the part of the pattern that has produced a major storm, or as I like to say a ‘signature’ storm each time through the cycle.  Keep in mind the cycle starts in the Fall.  The ‘signature’ storm has occurred on the following dates.

  • October 26 (Record low pressure readings, very strong winds, severe weather)
  • December 10-12 (Blizzards warnings, heavy snow and rain)
  • January 31-February 2 (Record setting blizzard hits Milwaukee & Chicago)

This storm will once again repeat and likely produce precipitation totals of 0.50″ to 1.50″.  Areas that see snow could be well over 6″, and I also expect a severe weather component in the warm sector of the storm.  I expect this storm system to impact a large part of the Midwest with rain or snow!

To clarify, this storm has sent a little piece of energy ahead of the main low on a couple of occasions, this may impact western/southwest areas of the Midwest first, then the main piece of energy would follow, likely closer to the 21-22 timeframe.  Some areas east like Chicago, Detroit, and Milwaukee could see effects into the 23rd.  But the key dates to watch are most likely right around the 22nd.

Here is the March forecast specific to southeast Wisconsin that was posted in the blog back on February 27.

March Forecast

We have been talking about this ‘signature’ storm in the blog since January!

March 28-30

Another strong clipper type system will push precipitation through in a narrower band.  I expect total precipitation to stay below a 0.50″ for most locations.

For March, I expect snow totals above average in Milwaukee and Minneapolis.  And think that Minneapolis could be 5″-10″+ above average for the month!

———————————————————————-

April Midwest Outlook

April 4-10

During this period I expect a major warm-up with temperatures during the day jumping at least 10 degrees above average for a 2-4 day window.  This warm-up can be traced back to the second week of November, the final days of 2010, and shortly after Valentine’s Day.  I believe this part of the pattern could bring the first 70s to the upper Midwest.

Here is what the 500mb(middle of the atmosphere) map looked like back on December 30.  There was a southwest flow aloft bringing in warmer air.  This southwest flow returned in February, and should again in early April.

500mb December 30, 2010 Big Warm-Up

Like most big Spring warm-ups, they can come crashing down.  A ‘wetter’ storm should arrive in the Midwest between April 8-11.

April 12-19

Likely quieter period with chances of ‘lighter’ precipitation.

April 20-May 20

The active part of the pattern will once again return.  This roughly 30 day stretch may produce some wild weather across the nation’s mid-section with the bigger storms returning, and warmer air trying to move north.  The result, is a chance of some large severe weather outbreaks.  How far north they push into the Midwest is a question that will be answered within a day or two of each storm system.

I would keep a close eye on April 21-23, April 26-28, and May 6-12.

————————————————————————————–

Those are the dates that need to be watched closely for ‘wetter’ storms.  Mother Nature can throw curveballs in at anytime, but using the LRC certainly increases our batting average when making long range forecasts.  We will continue to update the flood potential for the Midwest in the coming weeks, but right now it looks like the threat will increase over the next 2-3 weeks.

Please leave any thoughts or questions in the comments section of the blog!

Jeremy Nelson

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20 Responses

  1. Simply awesome.

    • The comparison to this coming weekend about blew me away. After 5 years you think I would be use to this!

      jeremy

      • Jeremy, last week I thought the Dec 3-4 system was what to expect for this Tue/Wed, but after analyzing your thoughts I know now I was mistaken. You have definitely steered me in the right direction during this active pattern. Another great learning experience. (There is just so much to look at and to take into consideration, the time to do so doesn’t always present itself)

        For reference, (I posted this last week as well) http://www.theplayerstour.net/osnw3/photos/20101204_locradar.gif

        Looking forward to watching this active stretch here on the blog!

      • Josh,

        Recently the pattern has stayed close to 50 days. Anytime you think it may be 47-48 days step back and look again. I have been fooled earlier in the year, but now we can look back at the previous 3 cycles.

        Jeremy

  2. Very interesting. Almost as if the atmosphere was controlled by man-made weather equipment… 🙂

    • That would be one big machine:) Thanks for reading the blog.

      Jeremy

  3. Awesome stuff, Jeremy! Superb post! 😀 Looking forward to seeing the end of March 😉

  4. Jeremy, I would like to offer some feedback on your blog. You tend to over-use the exclaimation point (!). From the reader’s viewpoint, this is distracting. If you wish to emphasize your point, perhaps you should consider underlining or italicizing the text. The information is fascintating, keep up the good work.

    • Dan,

      I have never specialized in grammar, but hope you enjoyed the weather angle.

      Jeremy

    • It’s a flippin blog! Not a college final paper! Great work Jeremy and Mark, keep it coming. The large storm is very exciting and to start seeing on the long range models is awesome! Hope to see some of our first severe weather of the year with that one!

  5. Why the shift from your earlier forecast (a couple of weeks ago) that the more severe storm would appear March 22-24? Now you feel it’s March 19 to 22 when we’ll see it. Is this a shift in cycle length? All this changing makes it hard to plan a picnic based on the LRC forecast.

    • Counting 50 days from the last signature storm which was February 1-2 would give us March 23-24 (because February is only a 28 day month). There was overrunning precipitation the day before on January 31 so that could bring it forward a day to March 22. So, I’m not sure if Jeremy miscounted because of the short month, but the weekend of March 19-20 should easily be safe from the signature storm.

      • Daniel,

        The weather pattern is repeating and this feature is coming back. No one should be surprised if it is on March 19, 22, or 24. The pattern has repeated around 46-52 days all year, with most events around 50 days. For our area the key dates are likely around March 22, but the impacts could be felt into 23-24 if the storm is a little slower. This is the ‘signature’ storm and should again produce a wet system with rain and snow, and potentially a lot of wind. So no, I didn’t miscount, I was just looking at a much larger area.

        Jeremy

    • Adrian,

      The forecast that I did last night was for the ENTIRE Midwest. I was asked some questions regarding flooding, so the dates may be different since we are not solely focused on southeast Wisconsin. Couple of things…one I challenge anyone to point to a long range forecast that will pinpoint when storms are going to hit an area within the span of several days, and give a reason why. We have been talking about the start of week 3 in March since January, not bad. Second, I analyzed the pattern more, and tried to narrow the gap. I looked at when certain events occurred leading up to the ‘signature’ storm, and then gave my best estimate. Parts of the Dakotas will be impacted before Milwaukee and Chicago. That is why in this forecast some of the dates were moved up.

      Hope this helps. And I would never recommend planning a picnic in March, regardless of who’s forecast you use:)

      Jeremy

  6. Jeremy —

    I’ve enjoyed watching you have “face-time” with us the last several nights on TV. Also, thanks so much for all the teaching you’ve shared with us via the blog the last several entries. Please don’t start charging us tuition! 🙂 Maybe instead of referring to you as my “Weather Guru” I need to refer to you as my “Weather Professor”! 🙂

    Thanks for including and welcoming even novices like me that find weather watching a fun passtime/hobby as part of your “WW 12 family.”

    Have a great week!

    Don

    • Don,

      I love talking about the weather on tv or here in the blog. Thanks for watching and reading. In our blog community we have some great participants that help all of us learn and you are a big part of that!

      Over the next few days we have lots to talk about with the active weather ahead.

      Jeremy

  7. Food for thought…

    The LRC is a great tool. Used with other tools, it provides an advantage in long range forecasting that isn’t found elsewhere – but..it is a tool. The atmosphere isn’t perfect nor is any long range tools exclusively or collectively. The LRC provides great insight in knowing if models are handling the pattern correctly as well as forecasting beyond model range. Like any weather model, time/space precision will become more broad the further out you look. It is the nature of the beast [pardon the pun]. Even in this more broad view, there is value knowing trends and regional behaviors.

    As many are still learning the LRC, I would encourage everyone to ask questions and participate. The LRC is a rapidly evolving concept and still much more needs to be learned. As the atmosphere is always shifting..the LRC adjusts as well. I would caution getting too specific on cycle durations as there is a “flex” from cycle to cycle. Also, due to seasonal variability, we will see that one cycle may not best to be compared to the prior – rather perhaps a prior cycle a time or two before with comparable jet strength, location and other teleconnective properties.

    The value is in knowing the pattern, approximate cycle and the associated long term long waves – and applying meteorological experience to creating a forecast that otherwise isn’t really available out there…

  8. lrcweather, excellent synopsis and advice. It also helps that you reiterate these points periodically. Out of site, out of mind. In regards to “forecasting beyond model range”… some people think I’m nuts when I proclaim such ideas. It’s basically the minority of people I discuss the LRC with though, as most have open minds to the idea. Especially when they participate and follow along.

    • Just want to let everyone know I added a statement in the blog under the March 19-22 forecast to clarify some of the questions. I also posted a direct link to the March forecast that is specific to southeast Wisconsin that was posted in late February.

      Jeremy

  9. Jeremy, keep using exclamation points! They just show how enthusiastic you are about what you do. I have learned more about the atmosphere and patterns in the last year following along here then I did in the previous 32 years (and I have always been a weather geek.) Keep up the good work.

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