The same bizarre and convoluted weather pattern that gave us Winter Storm Achilles has also put a lid on severe thunderstorm and tornado development over much of the country for the first few days of May.
Through May 4, only one tornado has been confirmed in the U.S., and it was a very weak one. May 2 brought an EF0 tornado with 70-mph winds to Boca Raton, Fla., tossing lawn furniture around, downing a few trees and fences, and breaking one window. The tornado stayed on the ground for just four tenths of a mile and was only 50 yards wide; nobody was hurt.
(MORE: Tornado Drought 2013?)
According to The Weather Channel's severe weather expert Dr. Greg Forbes (Twitter | Facebook), we would expect about 39 tornadoes in the first four days of the month based on the average of the past 10 years.
This month's big 'tornado deficit' inspired us to rummage through the data to find out how unusual it is to have such a quiet start to May.
It's Been Quiet Before
According to Dr. Forbes, the first tornado in May 1970 wasn't until May 8.
But we didn't have to go too far back to find another May that, like this May, started with just one tornado in its first four days.
That was May 1-4, 2005, when the nation's only tornado was also an EF0 in Florida. That one touched down in Basinger, Okeechobee County, on May 3, lasting four miles with a 40-yard-wide path. It too caused no injuries, blowing down a few trees.
How did May 2005 turn out? Activity did pick up somewhat, but the month finished at 123 tornadoes, which is less than half the long-term average for May. Even better, there were no tornado deaths in May 2005, and just three injuries. According to the National Climatic Data Center, total property damage for the entire month was less than $3 million.
One Deceptively Quiet Start: 2011
We all remember the blitz of incredibly deadly tornadoes in the spring of 2011.
What you may or may not recall, however, is how the severe weather pattern went eerily quiet for a couple of weeks in the middle of spring.
After the barrage of tornado outbreaks throughout April, the atmosphere took a bit of a breather for the first few weeks of May. From May 1-4, 2011, only two tornadoes touched down in the U.S., and neither of those did much harm.
One was an EF1 that hit Center Ridge, Ark., on May 1, knocking down trees. Two houses were hit by the falling trees, but nobody was hurt. The narrow twister lifted after less than a mile on the ground.
The other tornado was an even weaker EF0, a "landspout" tornado that touched down in open country south of Pueblo, Colo., on May 2, causing no damage at all. It lasted only three tenths of a mile.
But unlike 2005, May of 2011 would go on to roar back with a deadly vengeance, starting with a killer tornado in Reading, Kan., on the 21st, followed by the Joplin and Minneapolis tornadoes on the 22nd and another killer outbreak that targeted Oklahoma on the 24th.
The final tally for May 2011: an above-average 326 tornadoes, 178 deaths, well over 1,000 injuries, and billions of dollars in damage. The Joplin tornado alone caused about 1,000 times as much damage (in dollars) as all the tornadoes in May 2005 combined!
The takeaway here: When it comes to tornado season, Mother Nature can turn on a dime. A quiet May might stay that way, but a calm weather pattern can also turn ugly in just a few days.
MORE: The May 24-26, 2011 Tornado Outbreak
A tornado moves north in Canadian County after having just crossed SH-3, the Northwest Expressway, towards Piedmont, Okla. on May 24, 2011. (AP Photo/The Oklahoman, Paul Southerland)