Watch for dicey weather

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March 11, 2010 - 12:00 AM

With a small storm brewing a few miles south of Allen County, Brad Ketchum gave volunteer weather watchers and public safety personnel a two-hour tutorial Wednesday on what to look for when severe weather threatens.
Ketchum is lead meteorologist for the National Weather Service in Wichita and his presentation, “Storm Fury on the Plains,” was repeated scores of times throughout Kansas this week.
The weather service depends on three sources of information to issue severe weather watches and warnings, Ketchum said. Most prominent is Doppler radar, followed by a confirmed report from a weather spotter, and the environment in which a storm is unfolding.
“We use a two of three rule to determine when to issue a warning,” Ketchum said.
Doppler radar displays intensity in a storm cell and where rotation is in the cell. Experts such as Ketchum use that information to determine where tornadoes or severe weather features may develop.
Ketchum said the supercell that produced the huge tornado that struck Greensburg in 2007 developed the tightest and best defined rotation on radar that he had ever seen. But, Ketchum said, nothing is better than a confirmed sighting by an observer on the ground.
Anyone who sees unusual or threatening weather should report it immediately, either to the weather service by e-mail at weather.gov/wichita or by calling 911. The weather service will also accept reports by way of Twitter.
Ketchum said people should use the T-E-L approach in making a report: Time of the occurrence; event type: tornado, hail, high wind or heavy rain; and location, both of the spotter and the event.
“When you make a report, do it in real time,” Ketchum said. “Don’t wait, timing is important.”
Those wishing to become trained storm spotters should call Pam Beasley, Allen County emergency management director, at 365-1477.

TORNADOES are what most people think of when severe weather is mentioned, but other events cause more damage and often take more lives, Ketchum said.
During 2009 in the Wichita service area, which includes all of southeast Kansas, 48 tornados were confirmed and caused $733,000 worth of damage. Meanwhile, 376 severe thunderstorm warnings were issued and damage was $54.6 million. Flash floods, an outcome of rain accompanying thunderstorms, occurred 29 times and resulted in $6.8 million of damage.
Straight-line winds, such the inland hurricane that sweep through Allen County and much of the rest of southeast Kansas in 1986, can cause more damage than an F5, the most severe of tornadoes, Ketchum said.
He described in technical detail weather systems that frequently occur in Kansas.
— Single-cells storms crop up quickly and don’t last long. Rain is their prominent feature.
— Multi-cell clusters occur when several single cells group together to produce rain, sometimes hail, and rarely a tornado.
— Supercells have huge flat-top anvil clouds that stretch many miles from the storm’s center and generate updrafts and areas of rotation, particularly on the backside, that can develop into tornadoes. Supercells frequently maintain cohesiveness for hundreds of miles and commonly develop in a series.
— Squall lines are well-developed storm systems that usually stretch from horizon to horizon and produce hail, rain and high winds but seldom tornados. The linear cloud formations sometimes have appendages dangling from them that give rise to tornado reports, but “they are just SLCs,” Ketchum said, “scary-looking clouds.”
Another weather feature that occurs infrequently but rapidly is a micro burst, a powerful downward flow of air that in many cases causes more damage than a tornado. Straight-line winds also often produce more damage than a tornado, which has limited ground contact, Ketchum said.

WHEN SEVERE weather threatens, Ketchum said people should take every precaution to avoid injuries.
With tornados that means seeking shelter in a basement or the center of a home with “as many walls as possible between you and the storm.” He said having a first aid kit and flashlight in an accessible place is important, as well as “to keep your shoes on when you go to a shelter,” noting that nails, glass and other debris make barefooted walking dangerous.
He urged respect for lightning, which can occur anytime a thunderstorm is near. And flooding, he said, is one of the most underreported of weather events “and one of the biggest killers.”

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