The U.S. appears to be locked in a tornado drought as meteorologists have recorded only about two-dozen twisters so far this year during a period when 100 or more are typical.

And there have been no reports of tornadoes so far in March — a sometimes violent period for severe weather. The last time there were no tornadoes in March was 1969.

Forecasters at NOAA's Storm Prediction Center in Norman have issued only four tornado watches and no severe thunderstorm watches — less than 10 percent of the average 52 tornado watches issued by mid-March.

Warning coordination meteorologist Greg Carbin said there isn't one answer to explain the sluggish start, but that a persistent weather pattern of cold, stable air prevents a tornado's ingredients from coming together.