Stormchasers across Tornado Alley have been frustrated this spring by what seems to be a lack of tornadoes and severe weather.  Indeed, VORTEX2, the largest tornado field study ever, has been running for more than two weeks now and has not seen one twister.  Last week, Weather Channel Senior Meteorologist Stu Ostro speculated that global warming was the cause.

In a segment with on-air meteorologist Stephanie Abrams, Ostro explained that the jet stream lingering over Canada and a continual ridge of high pressure were suppressing severe weather.  Without the collision of low and high pressure (among other factors), tornadoes and supercell thunderstorms have a hard time forming.

Ostro continued his explanation saying that atmospheric pressure in the Northern Hemisphere’s mid-latitudes between 30 and 60 degrees has increased steadily since 1970.  He then overlaid a chart showing this increase with that of a chart that shows global average temperatures having increased over the same period.  As he says in his blog entry, “That parallels remarkably well the trend of globally-averaged temperatures, which has also shown a significant rise since the mid 1970s.”

For the rest of the story story – and a response from Stu Ostro – check out the complete story on the Denver Weather Examiner’s pages.