Larger hail criteria look to reduce severe thunderstorm warnings

Tuesday, March 10, 2009 | 11:00 a.m. CDT; updated 2:55 p.m. CDT, Tuesday, March 10, 2009

COLUMBIA — The weather service predicts fewer severe thunderstorm warnings this year.


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No, weather forecasters have not become psychics—the drop in warnings is due to a change in weather classification criteria. 

On April 1, the central region of the National Weather Service will begin using 1-inch hail as the standard a storm must meet in order to be classified as a severe thunderstorm. The previous standard had been the ability to produce three-quarter-inch hail, according to a video on the weather service's Web site. These storms prompt the weather service and local media outlets to issue warnings and alerts when storms are in the area.

One-inch hail is roughly the size of a quarter, while three-quarter inch hail resembles the size of a penny.

One reason the weather service cites for making the change is that storms really aren’t dangerous to property until they can produce hail that is one-inch wide. The weather service also fears that people are being desensitized by too many warnings issued for harmless storms, according to their Web site.

Jim Kramper, a warning coordination meteorologist for the National Weather Service in St. Louis, which oversees Columbia, feels people aren't paying enough attention to warnings.

"These new criteria will cause a drop in public warning, which is good because frankly, there are too many of them," he said. "We hope that after the change, when they (warnings) do come out, people will pay more attention to them.”

David Schmidt, chief weathercaster with KOMU/Channel 8, agreed that people are being desensitized.

“It’s kind of a ‘the boy who cried wolf’ situation," he said. "We run a crawl on the screen as long as the watch or warning lasts, some times for six hours at a time. It’s on screen far too to often and then people pay no attention to it. There has always been disagreement if hail below one inch is severe anyway, so I think that this is good news.”

Other reasons cited for the change are to reduce the frequency that media outlets inconvenience viewers by breaking into programming to issue a severe thunderstorm warning. It will also reduce the workload of volunteer storm spotters that can become weary from being constantly activated, according to the weather service's Web site, though there seems to be less consensus on those points.

“We have so many spotters, I don’t think we have a problem with spotter weariness. But I can imagine it in more rural areas where they only have a few,” Kramper said.

“I don’t know how much bearing it’s going to have on our operations,” said Curtis Varns, news director for ABC 17. “We report significant weather regardless of weather or not a warning has been issued ... Sometimes we can see things locally that the weather service cannot. We work closely with them but sometimes we have to make the call locally.”

 The new standard has been in effect in Kansas since 2005, and the weather service said that it was resoundingly praised by both media outlets and emergency managers as giving a new meaningfulness to issued warnings. The expansion of the new standard to the entire central region, which is the part of the country that most often sees hail, is the next step in a continuing experiment that the weather service expects will eventually become the national standard.

"We will continue to alert people of storms that will produce hail of any size," Kramper said. "You want to be careful when you are out there.”

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