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Thank you for stopping by the Weather Watch 12 blog! In today’s entry we will look at the long range forecast for February based on the LRC.
If you are new to the blog or just need a quick refresher.
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.
As I have mentioned many times, this year’s cycle duration is about 46-52 days. Overall most of the weather events have repeated about 47-50 days apart. After analyzing the pattern and surface results from October through early January, I was able to get a very good idea of what should occur this February.
Here is a week by week breakdown of the month ahead.
The first week of February should be accompanied by below average temperatures. As I stated back in mid-December, I still expect the coldest temperatures for Milwaukee to occur in this timeframe. Back in early November and again in December, about 7 days after our ‘signature’ storm, a trough dug into the Great Lakes.
Below is the 500mb map from November 4. As the pattern repeates, this large trough dropping into one of the main long term longwaves should push very cold air into the Great Lakes. Keep in mind back on November 4 there was no snow on the ground, and the arctic air was not residing to our north.
While the first week of February looks cold, the chances for snow appear to remain on the light side. A wetter storm could move through parts of the South and up the East Coast as the trough digs into the Great Lakes.
After a cold start to the month, temperatures should moderate early in this period. Snow chances would likely be provided by ‘Clipper’ systems. This period will be the transition from the cold start to the month, to a milder stretch of weather with the potential for above average temperatures.
During this period a trough will dig into the West, and this will begin to lead us into potentially the strongest storm of the month.
From around February 14-18 I expect the most active storm system of the month to impact the region. As a large trough digs into the West, milder weather should arrive across the Midwest. The previous two times through the pattern temperatures have been well above average.
I expect another mild stretch of weather, with chances for precipitation on multiple days. As the main storm lifts into the Midwest, the track will be key. Both times through the cycle the heavy precipitation has missed our area, with the main upper low staying over Minnesota.
Below is the 500mb map from November 14, the first time the storm appeared in the cycle.
The second time through the cycle the storm brought fog, drizzle, light rain, and very mild temperatures to our area from December 29-31. Below is the 500mb map from January 1, 2011 as the main storm ejected into the upper Midwest.
This storm will need to be watched as it could bring all types of precipitation to our area. I do expect temperatures in this period to be above average, possibly the warmest day of the month occurring here. Temperatures will then drop off and may be colder than average for a day or two behind the system.
Early in the last week of February a clipper system or two should pass by with chances for lighter precipitation, and also a shot of colder air.
The highlight of this week should be the final day or two of the month. Both in November and January a storm system produced around or more than 0.20″ of precipitation. In November it was nearly an inch of rain, while in January it was 2.7″ of snow. This system should once again move into our area as the flow turns more southwest to close the month. The month should also end with temperatures around average.
Now that I have provided my thoughts for each week of February, let’s take a look at the overall forecast for the month here in southeastern Wisconsin.
- Temperatures: Below Average
- Precipitation: Below Average (Likely Average to Below Average Snowfall)
If you are curious, the average precipitation in Milwaukee for February is 1.65″, while the average snowfall is 11.3″.
Those are my thoughts based on the LRC and the overall weather pattern. Let’s compare this to the Climate Prediction Center’s February forecast.
Below is the CPC’s precipitation forecast, which calls for increased chances for above average precipitation in southeastern Wisconsin.
When it comes to temperatures the forecast based on the LRC, and the CPC’s are both calling for below average temperatures.
I am confident of the February forecast that I posted above. But I just want to remind everyone that the forecast is made using the position of long term longwave ridges and troughs, the cycling weather pattern, and past surface analysis. Just one mesoscale event like a prolonged lake effect snow could mess up one aspeact of the forecast. That is why I try to provide my thought process and break the forecast down into weeks.
Thank you for reading and please post any questions or thoughts that you may have on the February forecast or the LRC.
Have a great day!