Texas tornadoes: How much warning time was possible? (+video)
Texas tornadoes that hit the Dallas area Tuesday resulted in no fatalities, in part due to timely warnings. But a new model could improve tornado warning times dramatically.
Powerful Texas tornadoes that struck the Dallas-Fort Worth area Tuesday were as noteworthy for what didn't happen as for the damage the powerful twisters inflicted – no deaths reported so far, and only a handful of injuries in a heavily populated area.Skip to next paragraph
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For many, the remarkably low casualty rate is a testament to several factors: the twisters struck during the day instead of at night, warnings were timely, cooperation between the local media and the region's National Weather Service forecast office was good, and the Texas public is well attuned to tornado hazards.
Between 1981 and 2010, Texas saw more tornadoes, on average, than any other state – 150 a year, versus 78 for Kansas and 62 for Florida, according to records kept at the National Weather Service's Storm Prediction Center in Norman, Okla.
Now, federal and university researchers are developing an approach to tornado warnings that could extend the lead time from 13 minutes or less today to at least 40 minutes, and perhaps longer.
Typically, forecasters issue a tornado warning if:
- Spotters report a funnel on the ground.
- Storm clouds that are rotating.
- Weather radar picks up the characteristic hook-like signature of storm rotation.
It's virtually a warn-when-you-see-it approach.
Dallas's brief warning
The idea behind the new approach – warn on forecast – is to provide local forecast offices with the tools to predict a thunderstorm's development, direction of travel, and any tornado's likely path well in advance of the storm's arrival. That forecast would be updated every five minutes to keep tabs on the storm's progress and allow for rapid updates as conditions change.
Initial tests with the system using data from two past storms yielded 40-minute lead times for warnings, notes David Stensrud, a researcher at the National Severe Storms Laboratory in Norman, Okla.
“We'd love to get to 60 minutes,” he says.
Residents of the Dallas-Fort Worth area had but a fraction of that. In some cases the warning that hit home was a last-minute phone call.
Forney, Texas, resident Sherry Enochs told ABC news that she spotted a large tornado heading toward her daughter's house not far away. Ms. Enochs recounted how she called her daughter, noted the twister, and at her daughter's request, hung up and sought safety in a bath tub, where the she clung to her young grandson and another toddler as the tornado hit her house. All three survived.
As many as nine twisters were thought to have cut across the region, in one case striking a truck depot and hurling long-haul trailers more than 100 feet into the air like an angry 5-year-old tossing Tonka trucks.
At Dallas-Fort Worth International Airport, where airport officials canceled hundreds of flights, more than 100 aircraft reportedly sustained some form hail damage.
According to the Red Cross, at least 650 homes in the area have been damaged – in some cases cleaved in half, with the surviving half looking as though it came through unscathed.
The value of a few extra minutes
Given few injuries and no fatalities, what would extra lead time from a warn-on-forecast approach buy a community?