Thursday, 4 August 2005: 11:45 AM
Diplomat Ballroom (Omni Shoreham Hotel Washington D.C.)
There is organization hidden in the chaos of the upper atmosphere. I have been monitoring weather patterns for two decades now. Sometime in the early 1990s I noticed that midlevel storms occurring at a given location in the early part of autumn seemed to recur at regular intervals near that location through that winter and into the following spring and summer. By the mid 1990s I noticed that it wasn't just a storm or two, but the entire pattern. And each year's pattern had never occurred before, at least not that I had ever seen. Long-wave troughs and ridges seemingly would set up in early fall and then become the major long-term long-wave troughs and ridges the rest of the season. A more complex part of this theory is that there is a long-term memory in the overall pattern. In other words, this long-term pattern may have ridge and trough combinations moving through the westerlies. After years of watching this happen, I am convinced that we can predict the winter-to-spring weather pattern with some reasonable accuracy by November 10th. After seeing the pattern evolve further, by December or January, we can then predict with more accuracy what will happen months ahead of time. In each of the past three years this overall cycle has featured a unique period. The 2004-2005 seems to have a 75-77 day cycle. In 2003-2004, it was more like a 54 day cycle, and in 2002-2003 it appears to have been a 35 to 37 day cycle. Before 2002-2003, I thought there was a predominant pattern of longwave troughs and ridges, secondary part to the pattern, and a third random part. However, I have noticed with increasing confidence that the three parts to the pattern just don't exist. I now believe that identifying the predominant pattern is by far the most important ingredient in seasonal forecasting. In summary, the weather pattern sets up between October 10th and November 5th. A cycle begins, with the length of the cycle depending on possible factors of amplitude of the flow and other factors yet to be identified. The first cycle usually finishes by the end of November but it may last longer, as was the case in 2004-05. After determining the mean long-wave positions by early November, I feel one can predict with reasonable accuracy where the temperature and precipitation anomalies will exist through the winter and spring, and likely into summer. I will use 500 mb charts and my own seasonal forecasts to show where the long-waves set up this past fall and how it was apparent that Southern California, Ohio, and New England were about to have very wet and exciting winter seasons. I will also show how the 2004-05 season demonstrated a 75 day cycle.
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