National Weather Service trains volunteers
Webster City-Although 2009 was a relatively quiet year for tornadoes in Iowa, it’s impossible to predict what severe weather may hit the state this year.
That’s why the National Weather Service is encouraging more Iowans, particularly those in rural areas, to become storm spotters.
“Spotting helps keep your community safe and saves lives,” said Mindy Beerends, a meteorologist with the National Weather Service, in Johnston, who spoke to a group of 30 people at a recent storm spotter training seminar in Webster City. “Our technology has limitations, and spotters’ input can help us provide more accurate warnings and reduce false alarms.”
Storm spotters’ help is especially valuable during this time of the year, since the peak tornado season in Iowa occurs in May and June.
In 2009, Iowa experienced 25 tornadoes-23 below the 30-year average of 48 tornadoes per year.
June 21 was the busiest day for tornados in the state last year. Tornadoes aren’t the only spring and summer storms of significance, however.
“Some severe thunderstorms can be just as damaging as tornadoes, in terms of their economic consequences,” Beerends said. “That’s why we need storm spotters in rural Iowa to help us keep an eye on the sky.
“A proactive approach to spotting before storms enter a county is vital to the warning process.”
Successful storm spotting
Beerends offered the following tips for successful storm spotting:
- Prepare and deploy. Stay informed through a NOAA All-Hazards Weather Radio, an AM/FM radio, television reports and weather updates on the Internet, including www.weather.gov/desmoines, to stay abreast of severe weather watches and warnings, radar imagery and potential safety concerns.
“When a warning is issued for a neighboring county, that’s a good time to start storm spotting,” Beerends said. “By the time there’s a warning for your area, it may be too late for spotter activation.”
- Understand thunderstorm basics. The thunderstorm lifecycle requires three basic ingredients, including moisture, instability (when warm air is present at the surface and colder air is present farther up) and a source of lift (which usually comes in the form of warm fronts and cold fronts).
The greater the instability, the stronger the updraft and the greater the chance of stronger storms. “Updraft characteristics to watch for in the sky include cumulus towers, where the cloud looks like cauliflower; possible wall clouds; and anvils, where the top of the cloud is shaped like an anvil,” said Beerends, who noted that strong updrafts can also have a rain-free base.
Also watch for downdraft areas, which are the dark regions of a storm and include a rainfall area. “It’s important to locate the updraft-downdraft interface, because this means conditions are favorable for large hail,” Beerends added.
- Know how to identify funnel clouds versus tornadoes. Wall clouds associated with severe storms tend to be persistent and are often rotating.
They can also be a precursor to tornadic development.
“To determine whether you’re seeing a funnel cloud or a tornado, report it to the NWS as a tornado if it extends halfway or more to the ground,” said Beerends, who noted that the visible funnel of a tornado may not always reach the ground.
“Also, always check the ground for debris circulation, because that’s the sign of a tornado.”
Small tornadoes in the EF-0 and EF-1 range are the most common in Iowa. They are also the most difficult to detect with radar, Beerends said, because they are short-lived.
- Understand the different types of thunderstorms. Multi-cell storms are very common in Iowa and occur when several storms at various stages of developmpent occur at once.
Super-cell storms include persistent, rotating updrafts and typically show a counter-clockwise rotation. In fact, super-cell tornadoes are often preceded by a rotating wall cloud or rear-flank downdraft, said Beerends, who noted that the RFD is a “clear slot” on the left-rear side of a wall cloud.
- Report critical information. To make a report to the NWS, call (800) SKY-WARN. Don’t just report the obvious weather hazards like severe thunderstorms, hail and tornadoes.
Watch for funnel clouds, rotating wall clouds, winds higher than 40 miles per hour, heavy rain and flooding.
“Flash flooding is the number-one weather-related killer in the country, and we appreciate receiving flash flooding reports as much as the other weather reports,” Beerends said.
Also, when you make a report, say who you are, what you’re seeing, where you are located (reference the nearest town or street location), and note the time of the event.
- Stay safe. If you spot a tornado and it appears to be in the rope stage or looks like it’s dissipating, be careful.
“This doesn’t mean it’s any less destructive than before,” said Beerends, who also urges storm spotters to also be extremely careful when lighting is present. “Lighting can strike up to 10 miles away from a thunderstorm. If you can hear thunder, you are at risk.”
To register as a new NWS storm spotter, send your name, mailing address, residence address (if different from your mailing address) and phone numbers (home, work, cell) to firstname.lastname@example.org.
If you don’t have e-mail, you can also send this information to SVN Spotter Program, NOAA/National Weather Service, 9607 NW Beaver Dr., Johnston, IA 50131.
Once your information has been received, your application will be confirmed and a spotter number will be assigned via return e-mail or postal mailing.
Please allow up to two weeks for a reply.
Contact Darcy Dougherty Maulsby by e-mail at email@example.com.
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