Storm was worst here since 1967

April 23, 2011--- James Shrum Jr. slides down his grandmother's caved in garage roof as his father James Shrum spots him. The father and son were checking out the damage to the roof of Nancy Shrum's home on Bern Avenue in Granite City Saturday morning. Emily Rasinski erasinski@post-dispatch.com

April 23, 2011--- Chris Humphreys pulls off the roof of a neighbor's garage that was blown onto the home he rehabbed and looks after for an older woman at the corner of Wabash and Ball Avenue in Granite City Saturday morning. Emily Rasinski erasinski@post-dispatch.com

The last time there was such severe and widespread damage here was on Jan. 24, 1967, when a tornado traveled 21 miles on a path similar to the one Friday night, the Weather Service said.

That '67 storm was considered the fourth-worst tornado to ever hit the area.

"People are going to remember this for a long time," said Jim Sieveking, lead forecaster at the Weather Service here.

The storm on Friday produced tornadoes from New Melle in St. Charles County all the way across the Mississippi River to Granite City.

Weather Service surveyors are trying to determine whether it was one tornado that stayed on the ground, or several.

The Weather Service did confirm tornado touchdowns in New Melle, Bridgeton and near Granite City. At those points, the surveyors were able to determine the strength of the tornadoes from the rubble left behind.

Bridgeton was hit hardest, with an EF4 tornado. It packs winds ranging from 165 to 200 mph. (An EF5 is the strongest category of tornado.) Lambert-St. Louis International Airport and Pontoon Beach near Granite City each had an EF2 touchdown — indicating 111- to 135-mph winds — and the twister in New Melle measured as an EF1, with winds from 86 to 110 mph. Forecasters believe a tornado also touched down in Maryland Heights, where they detected swirling debris on their weather radars.

In determining a touchdown, surveyors look for telltale signs: convergent patterns in the damage, twisting and turning of tree limbs, houses removed from their foundations.

Friday night's storm system was termed a supercell thunderstorm, and was far worse than the squall line thunderstorm that hammered Sunset Hills and other areas on New Year's Eve, Sieveking said. Squall lines are famous for their damaging winds but don't usually produce tornadoes — and when they do, the twisters are short-lived, he said. Supercell thunderstorms are known for long-path tornadoes, hail and damaging winds.

The 1967 storm first touched down in Chesterfield and then headed northeast at 40 mph. It was on the ground for 35 minutes, according to the Weather Service, and left a path of destruction ranging from 50 to 200 yards wide.

There were 216 injuries and three fatalities as a result of that storm. Property damage was significant, with 168 homes destroyed, 258 with major damage, and 1,485 with minor damage. At least 600 businesses were damaged or destroyed.