Persistent cold behind record lull in tornadoes

For the first time since reliable recordkeeping began back in 1950, not a single tornado has been reported in March in that world tornado capitol, the United States of America.

The previous longest wait for  March tornado occurred in 1969, when a sighting wasn't confirmed until March 23, according to Greg Carbin, the warning coordination meteorologist at the Storm Prediction Center, in Norman, Okla.

The atmosphere almost certainly will get friskier, and soon, and thunderstorms are possible around here on Thursday.

But so far this season the storm center has issued only four severe-storm watches – criteria is winds of 57 m.p.h. and/or 1-inch diameter hail, Carbin said. On average, it would have issued 60 by now.

What's not going on?

Much of North America has been  locked in a remarkably relentlesst large-scale pattern, with ridges of high pressure in the west and troughs of low pressure in the East.

That pattern has delivered cold and snow to the Northeast, and baked California. "This has been one of those that has been very odd in terms of longevity and persistence," Carbin said.

It also has act as a severe-storm suppressant, said Carbin, repelling moisture and mitigating the instability needed for severe storms.

Although that pattern is going to reassert itself by the weekend, Carbin says that is going to have to give ground and air to the reality of the spring sun.

"The atmosphere is going to catch up to the calendar," he said.