Winter Forecast 2007 – 2008
Issued: November 16, 2007
by Gary Lezak

Our winter forecast is based on the LRC (Lezak’s Recurring Cycle), my weather pattern theory:

1. The weather pattern sets up between October 1st and November 10th
2. "Long term" longwave troughs and ridges become established
3. The pattern begins cycling and continues into the next summer
4. Every year is unique

We have considered other factors while making this winter forecast. La Nina has been growing in strength. La Nina is the cooling of the tropical Pacific waters and has been shown to affect the climate over many parts of the Earth. For Kansas City, however, we have found the La Nina impact to be rather small. There have been 17 La Nina’s since 1950. Kansas City has had wet La Nina winters, dry La Nina winters, cold ones and warm ones. Snowfall has trended to be a bit lower, on average, during La Nina years in Kansas City, but this is also a highly variable statistic (a few of the La Nina years had well above average snowfall) and another indication that La Nina is just a minor influence on something much bigger that is going on…….the LRC!

What is a "long term" longwave trough or ridge? These are larger features in the overall weather pattern that recur at regular intervals as the cycle begins repeating. The cycle has not been determined for this winter as of November 16th. The cycle is determined once we can show that the weather pattern is repeating. This usually happens by sometime in December or at the latest early January. As soon as we can identify the cycle then more specific long range forecasts are possible. Last year we accurately predicted storm systems that regularly repeated every 42 to 45 days. These predictions were often made weeks or even months ahead of time. What will the cycle length be this year? We don’t know yet.

A unique weather pattern has set up again this year! This weather patter evolved between October 1st and November 10th as the LRC implies. Last year’s weather pattern sort of morphed/transitioned into the 2007-2008 weather pattern between August and early October. By around October 7th or 8th we found the old pattern to have finally faded and the new one to have begun. We have noticed three main phases to this weather pattern. We will call them Storm tracks 1, 2, and 3. I will discuss where these storm tracks are located, what they mean, how we know that they are there, and then we will make our winter forecast based on these "long term" longwave troughs. There are also mean “long term” longwave ridges that are also a major factor and these will be discussed as well.

Storm track #1: Between October 7th and October 25th? A "long term" longwave trough developed and became established across the northeastern Pacific Ocean. This extended from the western part of Alaska southeast through the Gulf of Alaska extending southeast, negatively tilted, into the western states. The energy from this trough then dives into the western United States and waves across the nation bringing a series of strong storm systems to our region. When Storm Track #1 amplifies we will likely see our strongest storm systems of the season. This stormier part of the weather pattern lasted for 7-10 days. This part of the pattern will likely produce 75% of our winter precipitation total.

Storm track #2: Between October 25th and November 10th there was an evolution of a deep trough across central and eastern Canada extending south into the Great Lakes states. There is no denying this feature. It is part of the pattern. And, suddenly it is showing more amplitude as we can see on the latest computer model guidance for Thanksgiving week. When this storm track amplifes it will provide the conditions for Arctic outbreaks, but how often will this happen? As soon as we know the length of the cycle we will be able to answer this question. This part of the pattern will likely produce only 20% of Kansas City’s winter precipitation total, but could produce most of the snow.

Storm track #3: Storm track #3 is the de-amplified versions of storm tracks 1 and 2. This is the pattern that has dominated North America thus far. And, it will likely lead to long dry spells and warmer winter weather. This part of the pattern will mostly be dry and produce only 5% of the total precipitation this winter. And, if this part of the pattern dominates, as it has thus far, we could end up with a rather dry winter.

KANSAS CITY AREA
1 or 2 Arctic Outbreaks
Maybe 1 ice storm
Above average temperatures
19 inches of snow

Snowfall prediction probability chart (November 1st to April 15th)
Chance of 4" to 10": 20%
Chance of 11" to 14": 25%
Chance of 15" to 19": 40%
Chance of 20" or more: 15%

We plan on using the LRC more this year than ever before in making short term and long term forecasts. Last year we predicted the killing April freeze weeks ahead of time. “The storm” was predicted accurately weeks before the January 12th, end of February, and April versions of that storm system returned in the cycle in various forms. The LRC has been applied and we plan on expanding its role this year by doing monthly outlooks on NBC Action News at the end of each month for the next 30 days. We will attempt at getting somewhat specific, but this will be an experimental project. This monthly forecasting will likely begin in January after we have defined this years cycle.

The Cycle: The LRC is now set and cycling. This is another unique pattern (it has never happened before). The cycle has not yet been defined. Maybe there is a way to figure it out by now, but until we see the pattern repeating the cycle is very difficult to determine. We have not seen the pattern repeat yet, as of November 16th. The cycle varies from year to year as well dependent on factors yet to be determined. Last year had around a 45 day cycle. The year before was around 62 days. Once the length of the cycle is determined then we can look forward and make forecasts. Our confidence in the cycle and these forecast grows as we get through the second cycle and move into the third and fourth ones. The pattern likely continues through the spring and into the summer before morphing or transitioning into next years LRC in October. And, look for storm track #1 to repeat. When it does come back then we may have our first guess at the length of this year’s cycle.

This year’s pattern has three main storm tracks and most of our winter excitement will come out of storm tracks #1 and #2. But, Storm track #3, as described above, may dominate. We are expecting another dry year from Southern California into the desert southwest. Los Angeles just had their driest year on record and this weather pattern should bring them below average rainfall again, but not quite as low as last year. The southeastern drought may get a break when storm tracks #1 and #2 produce a few wet systems.

Temperatures will likely be above average from the southwest into the plains. Near average temperatures will be dominant elsewhere. There will likely be at least a few set ups for Arctic air when storm track #2 amplifies. Look below at the forecasts for precipitation and temperatures this winter.

If we are going to have near average precipitation it will take storm track #1 to produce some wet systems. How often will this track repeat? We aren’t sure yet, but likely two or three times this winter we should have the Gulf of Alaska energy dive into California and then track into the plains with some strong wet storm systems. 75% of our precipitation total will likely come from this set up. 1 or 2 Arctic outbreaks are likely when Storm Track #2 repeats, but we have concerns of long dry spells and warmer periods when Track #3 takes over.

We are expecting:

• 1-2 Arctic outbreaks
• Maybe 1 ice storm
• Above average temperatures overall
• Near average precipitation
• Below average snowfall