EARLY TUESDAY EVENING OKLAHOMA TORNADO UPDATE:
The Moore, Oklahoma tornado has been upgraded to an EF5 with winds of 200-210 mph as determined by damage assessments. The tornado's track length was 17 miles, on the ground for 50 minutes from 2:45PM to 3:35PM CDT and had a maximum width of 1.3 miles according to the NWS office in Norman, Oklahoma.
The NWS office in Norman, Oklahoma has a comprehensive slide presentation which illustrates the chronology of events leading to the tornado event HERE
|Oklahoma Tornado, May 20, 2013 - Courtesy: Christie Lightfritz|
Vivid video of the tornado on the ground
The evolution of the Oklahoma Tornado....
|Tornado Path: Courtesy; KFOR-TV|
Before people start criticizing the forecasting of this outbreak, remember this:
There WAS advanced warning of severe weather and the strong possibility of tornadoes. In fact, last week I remember mentioning the possibility for severe weather in the middle of the country late last week MORE THAN 5 DAYS OUT! The National Weather Service in Norman, Oklahoma issued a tornado warning 16 minutes before it touched down; 30 minutes before it hit the population center of Moore, Oklahoma. That might seem like a lot of time but in a tornado situation, this is an eternity. This doesn't bring back the people lost but it does show that severe weather forecasting is getting better. Ultimately, this will save more lives in the long term.
Now the wind speeds...
Most wind speed measuring devices don't survive the tornado. Only a few dozen tornadoes have has their winds directly measured. Maybe you've seen the "Doppler on Wheels" on storm chasing tv programs. The greatest wind speed EVER measured was done by "DOW" on May 3, 1999.
Although the proliferation of these doppler radars has increased as storm chasing becomes more frequent (partially driven by consumer demand--reality tv), the wind speed data from tornadoes is still determined by examining damage as noted in the first graphic from the NWS Tuesday afternoon.
Now for some historic tornado data...
Has EF5 tornado frequency increased? Data indicates that it has decreased overall since the 1970s
Only 58 tornadoes of EF5 strength have occurred since 1950. Most occurred in the 1950s, 60s and 70s. Here is the map with the tornadoes numbered in order of occurrence.