science

This month’s weather has been very cruel in parts of the United States. A long-standing record for the number of April tornados has been broken – with a great many lives lost – and with the current North American temperature conditions, more may be coming in the next few weeks.

Tornados occur every year in North America, usually in the spring, starting in the southern part of the central United States and moving northward as the season progresses.  However, tornados have occurred in every month of the year and in every state of the United States – though not unknown in other parts of the world, by far the largest percentage of tornados occur in the USA, which averages about 1,200 tornados a year.

While there is a lot known about tornados and the conditions from which they tend to develop, there is still a lot unknown and, perhaps, some aspects that will forever be unknowable.

Strong winds, strong wind shear (significant differences in speed and direction of wind, varying with height), an unstable atmosphere and abundant low-level humidly are all contributors to the formation of tornadoes.  Wind shear, “the kind which develops when cold and warm air masses ‘collide’”¹ is the key.

Active tornado seasons in the U.S. are almost always due to unusually COOL air persisting over the Midwest and Ohio Valley longer than it normally does as we transition into spring. ¹

Lately, I’ve been watching and reading weather predictions from a new meteorological consulting firm, WeatherBell Analytics LLC, where Joe Bastardi, formerly of AccuWeather, said on April 2oth:

While the next 5 days sees another moderate outbreak of severe weather this weekend ( and the snow again on the northern side) its next week another lawyers, guns and money outbreak takes place. We are liable to see another 100 to 200 tornadoes before the month is out, making it the most active April ever. My reasoning for this is based on the major, and progressive, trough that swings into the plains early next week, and is leading a major crushing of the eastern ridge that will then take us into a May much like 2008 temp and precip wise.

It’s natural for people to want to find a reason when something bad happens and, all too often lately, the favorite culprit of anything bad in nature is climate change (aka global warming).  However, tornadoes are one feature of nature that is not predicted by global warming theory.  If anything, a warming globe would reduce the frequency of tornadoes.

It is well known that strong to violent tornado activity in the U.S. has decreased markedly since statistics began in the 1950s, which has also been a period of average warming. So, if anything, global warming causes FEWER tornado outbreaks…not more. In other words, more violent tornadoes would, if anything, be a sign of “global cooling”, not “global warming”.¹

The ever improving weather knowledge of forecasters and meteorologists doubtlessly gave sufficient warning that saved many lives this month.

With every passing day, it seems, more precise digital tools emerge to clarify the inner heart of a storm cell in rampage. And yet, for all that solid information, the natural world can still seem murky, unpredictable and downright scary when it roars into full-throated chaos.

Tornadoes in particular, researchers say, straddle the line between the known and the profoundly unknowable.²

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¹ MORE Tornadoes from Global Warming? That’s a Joke, Right? – Dr. Roy Spencer
² Predicting Tornadoes: It’s Still a Guessing Game – The New York Times

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