Homes in Lancaster, Texas lay destroyed by a tornado on Tuesday, April 3, 2012. (Khampha Bouaphanh/AP)

The EF scale, ranging from 0 to 5, classifies tornadoes based on their wind gusts and associated damage. EF-2 and higher tornadoes contain 3 second wind gusts of at least 111 mph and are considered the most destructive and deadly.

* The tornado in the vicinity of Kennedale/Arlington was rated at least EF-2 and damaged 300 homes.

* The Lancaster/Hutchins tornado was rated EF-2 with maximum winds of 130 mph. It damaged 400+ structures.

* The Forney/Rockwall county was rated EF-3, with maximum winds of 150 mph.

Several reported tornadoes tore through the Dallas area on Tuesday, tossing semis in the air and leaving crumpled tractor trailers strewn along highways and in truck stop parking lots. (AP/KDFW-TV)

Consider the power of the tornado that tossed tractor-trailers weighing tens of thousands of pounds into the air like toys.

“It looks like the Dallas-Fort Worth area really dodged a bullet,” Dallas Mayor Michael Rawlings told CNN. “I mean we’ve got hundreds and hundreds of homes destroyed but amazingly no fatalities.”

The Minnesota Public Radio weather blog Updraft offered the follow possible explanations:

The tornadoes tore through a mix of suburbs and open country. . . .

It appears a combination of timely tornado warnings and just plain dumb luck saved lives Tuesday

YouTube video of Lancaster tornado - incredible close-up footage.

AccuWeather’s Mike Smith is convinced timely, accurate meteorological warnings were primarily responsible for the lack of fatalities.

Yes, luck always plays a role but that fact is the timely watch and warnings from the NWS, from the local television and radio meteorologists, and from AccuWeather Enterprise Solutions to our commercial clients are largely responsible for this happy outcome.

A USA Today story mentioned possible other factors:

* Sirens sounded in advance of the storm

* The storm hit when most people were at work and not in their homes

* While strong, the tornadoes were not EF4 or EF5 intensity, the most deadly

Unbelievable YouTube video of tornado in Arlington, Texas with multiple-vortices.

Was this tornado outbreak unusual?

Yes and no.

AccuWeather’s Henry Margusity said “I have never seen two tornadoes hit two large metropolitan areas [Dallas and Ft. Worth] at the same time before”

On the other hand, consider:

* April is the busiest month for tornadoes in Texas.

* Over the last 60 years (since 1952), a total of 172 tornadoes have been reported in either Tarrant or Dallas counties, Texas. Of these, 42 have been rated at least an EF2 (wind speeds over 110 mph). The strongest, rated EF4, hit Dallas on April 25, 1994, killing three people and injuring 48. Neither county has ever reported an EF5-rated tornado (National Weather Service, via AccuWeather)

* The blog U.S.Tornadoes notes: “When it comes to tornado outbreaks near Dallas and Ft Worth since 1950, there have been about 20 that have produced 5 or more tornadoes in the following counties [in and around Dallas]: Tarrant, Wise, Denton, Johnson, Ellis, Dallas, Collin, Kaufman, Rockwall, Parker, Hunt, Hopkins.”

U.S. Tornadoes also noted that Tuesday’s outbreak was just one calendar day removed from Dallas’ deadliest tornado (F3 intensity) on April 2, 1957.