You may often hear us talk about long term weather forecasts in meteorology. One of the popular long term forecasts is NOAA’s hurricane season outlook. This usually gives us an idea of how many named tropical storms, hurricanes, or major hurricanes are possible. Researchers are also testing new methods for seasonal outlooks on tornadoes.
Recently an article was published in the Geophysical Research Letter titled “Association of U.S. Tornado Occurrence with Monthly Environmental Parameters.” The authors, Michael K. Tippett, Adam H. Sobel, and Suzana J. Camargo, constructed a monthly tornado index based on atmospheric variables. I thought this article was very interesting so I wanted to share. Their work suggested that if you can demonstrate a relationship between monthly averages parameters, like precipitation for example, and monthly tornado numbers, then you can provide a framework for a long range forecast.
The researchers looked at thirty years of climate data and determined two weather factors that were linked with active tornado months. The first was high wind shear, which is a change in wind speed and direction with height. A second factor was months that had heavy rainfall. The method of examining these two variables was tested and did bring positive results for some months, especially for June. So if you could accurately forecast wind shear along with precipitation, perhaps we could determine a month in advance that more tornadoes are possible.
This is the first time a monthly forecast has been demonstrated in such a way but like all forecasts it highly depends on how well you can predict the rainfall and shear. This is exciting stuff and hopefully scientists will build upon this research to create a forecast index in the future. We could certainly use utilize this type of information here at home, as we gear up for severe weather seasons.
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