Having established a statistical significance to Piers Corbyn's methods I now want to know how he does it.
In December 2013 Corbyn did an interview with meteorologist and BBC weather presenter Paul Hudson. Hudson admitted that Corbyn had a success rate greater than chance. He was asked if inaccuracies in the forecasts were due to errors in forecasting the sun or due to misunderstanding the relationship between the sun and the atmosphere. Corbyn replied it was the latter. He stated that he didn't fully understand the relationship between solar magnetic particles and the atmosphere but that he had identified a statistically verifiable connection. The interview answered some of the questions I raise at the end of my analysis.
A couple of documents I have found on the internet might provide hints at how the SLAT method may work, though there is not yet a firm conclusion.
The following document mentions a statistical link between solar magnetic particles and the weather in the lower atmosphere in the same vein as Piers Corbyn, but is unclear about how the connection actually works:
http://history.nasa.gov/EP-177/ch3-5.html
"A study of short-term weather patterns by Walter Orr Roberts of the University Corporation for Atmospheric Research and Roger H. Olson of NOAA suggests that weather may be affected as the spiral-shaped interplanetary magnetic field rotates past the Earth. They found that about a day after the boundary between inward-pointing and outward-pointing sectors sweeps by, there is a decrease in the number of low pressure weather systems forming in the Pacific Ocean off the western United States and Canada. Because these low pressure systems give rise to most of the storm centers that pass over North America an understanding of this effect may ultimately assist in making weather predictions.
Like most suspected Sun-weather connections, the effect seen by Roberts and Olson is hard to explain. The problem is that the amount of energy present in the weather phenomena themselves far exceeds the energy that apparently is available from the variations in solar activity. In this case, the low pressure storm systems in the Pacific contain far more energy than do the particles and magnetic fields which enter the Earth's magnetosphere from the solar wind. If the Roberts-Olson effect is real, then there must be an amplifier mechanism, whereby the magnetic variations trigger the changes in the weather. But the nature of the amplifier mechanism is currently unknown. "
Researchers at NASA have suggested that the weather in the lower atmosphere can influence the magnetic situation in the upper atmosphere:
http://www.nasa.gov/centers/goddard/news/topstory/2006/space_weather_link.html
Might this effect work in reverse somehow - ie, that changes in the magnetic levels of the upper atmosphere work to change the weather at surface level?
Might the amplifier effect be to do with the movement of particles through the magnetic field of the Earth acting like a generator? I'm no scientist and I can not think how this could translate into the movement of huge volumes of air, but it's a start.
There is also some suggestion that solar UV light may have an effect on the weather:
"The probable mechanism is the change in the solar UV radiation, which has an influence on the temperature gradient, ozone formation, and the winds in the stratosphere. This in turn disrupts the Jetstream in the northern hemisphere, leads to blocking weather patterns, and to easterly winds that lead to cold spells. "