***I am only adding a small update to Jeremy’s 12/15 post. Because it is an extensive post and our weather is benign, I will let it breathe another day.***
Good weekend for holiday travel and shopping. I’m closely watching the possibility of accumulating snow Monday – Tuesday. Look for a detailed forecast in the blog on Saturday. Thanks.
***Watch WISN 12 News at 5, 6, & 10pm for the latest weather information!***
Thank you for stopping by the Weather Watch 12 Blog! In today’s blog we’ll look ahead at the long range forecast for the rest of December and through January. The long range forecasts that we provide here in the blog are based off the LRC. If you are new to the blog or need a quick refresher, here are the basics of the LRC.
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 the Summer. The cycle length will vary each year. I’ve seen cycles of 42-46 days, 60-62 days, etc. The easiest way to view the LRC is to look at maps in the middle of the atmosphere, the 500mb level. The 500mb level is really a good spot to analyze the trough(lows) and ridge(highs) positions to help determine the long term longwave ridges and troughs. At the 500mb level you also don’t have to factor in friction or surface moisture. The theory can be translated down to the surface(where we live), which we do in this long range forecast.
Here is a video of our winter forecast based on the LRC, this was issued November 23.
After this year’s ‘signature’ storm hit the area again(previous time was October 26) over this past weekend the cycle duration and pattern are now very clear. This year’s cycle lenth is around 46-48 days. Now that the cycle duration is known and also the location of the long term longwave ridges and troughs we can start to project forward and make accurate long range forecasts!
We’ll break most of the long range forecasts into week increments.
This period is right around the corner, and parts of it are currently in our 7 day forecast. Back on November 4 an upper level trough dove into the Great Lakes, followed by a push of colder air.
This trough should provide chances of snow around December 20, likely our best chance of accumulating snow in this time window. Once the trough slides east, another pocket of cold air should drop in for 2-3 days.
At this point I do not expect a major storm on Christmas Eve or Day.
December 26-January 1
The first couple of days of this period may be quiet, but then closer to the New Year the weather should become more active. Back in mid-November a series of upper level troughs moved into the northern Plains and upper Midwest. I expect this feature in the cycle to once again fall into the favored long term longwave position.
Below is the 500mb map from November 13, 2010. This shows the general trough with the upper lows over the Plains and parts of the Midwest.
Now fast forward 47 days. This should mean a moderation in temperatures as the trough nears, and then a chance for a storm system around December 28-30. This would likely bring a chance of snow to the region, and then a push of arctic air to end the month and ring in the New Year!
If you are traveling to the Rose Bowl in southern California around this time to watch the Badgers, I think the trough and cold in the central U.S. should allow for the West Coast ridge to nudge into California and provide for nice, warm weather!
What I expect to be an overall active month of January should start out with the chance of a clipper moving by around January 3-4. It may be slightly stronger than most, so some snow is possible.
The part of the pattern that will repeat during this time window could bring a major storm to parts of the country. Here’s why. Back on November 22 a strong southwest flow developed, with several waves riding northeast along the flow.
Below is the 500mb map from November 22 showing the southwest flow.
Over a 5 day stretch from November 21-25 Milwaukee picked up over 1.25″ of rain. I again anticipate several waves to move into this favored long wave position beginning around January 5-8.
I think this part of the pattern has the potential to produce an ice storm in parts of the Plains or southern Midwest. Often the very cold air at the surface will get trapped under a southwest flow like the one shown above. After living in Kansas City for several years, where ice storms occur more frequently, the map above to me combined with pieces of energy flowing along it hints at this possibility.
Farther north around Milwaukee, I think this will bring us rounds of precipitation. If the main piece of energy can once again eject into the long term longwave, I think this period could produce a major winter storm around southeast Wisconsin.
Below is the 500mb map from November 25 when the strong upper low was over the Dakotas.
As this storm exits, another chunk of arctic air should drop south.
Second Half of January
The second half of January may also be very active. A couple of features stick our during this timeframe. The first will be how a storm around November 29-30 will track this time through the cycle. I think this will present a chance for snow in our area around January 15 give or take a day. Below is how the feature looked back in late November.
The storm that I am really waiting for should arrive around January 27-28, this is in my opinion the ‘signature’ storm of this year’s pattern. It has already occurred on October 26 and also December 11-12. This storm could bring a major winter storm to the region. It will also be followed by a blast of arctic air that in my opinion will bring the coldest temperatures of the winter to our area! The cold would likely stick around into the first week of February.
An average January in Milwaukee produces 15.2″ of snow. This January I am expecting above average snowfall, with totals above 20″! I just feel that there are a lot of ‘good’ opportunities this month to catch snow, and this should add up over 31 days to a healthy total.
Back in late November I issued the winter forecast. One thing that is becoming very clear is that temperatures are going to struggle this winter to warm-up. December has been well below average, and overall this winter will most likely continue that trend and end up as a whole below average. When looking at the pattern I should have realized this sooner due to the proximity to both of the long term longwaves that are dominate in this year’s pattern.
The temperature forecast did lean in this direction mentioning at least one month with below average temps and multiple below zero readings. So if you are hoping for drastic change to warmer weather you may want to temper your expectations.
If you have thoughts or comments on the long range forecast please ask! I hope you enjoyed reading and please stop back soon!