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Thursday, May 5, 2016

Weather school teaches what to look for in severe weather

Monday, March 1, 2010

GREENCASTLE -- In 20 days it will be spring in Putnam County. This season brings much more than milder temperatures and tulips and it often brings severe weather.

Putnam County storm chaser Chris Edwards knows firsthand about severe weather here. For 23 years he has been driving into thunderstorms and reporting about them to the National Weather Service (NWS).

He coordinates a severe weather spotting training session every year with the NWS, teaching local storm chasers what to look for and report during thunderstorms, tornadoes and floods.

"This class tells you how to identify a tornado in order to help the Weather Service give more accurate warnings," said Edwards.

NWS Meteorologist Mike Ryan presented a two-hour session talking about cloud and wind patterns associated with severe weather, how to interpret weather radar data and how to remain safe during severe weather.

A lot of attention was given to the formation of clouds, including fronts, shelves and squall lines and super cells. Straight-line winds are another danger of storms and are responsible for most thunderstorm wind damage. Winds can exceed 100 mph in these storms.

Ryan talked about the current weather patterns affecting temperatures and weather.

"We've been in an El Nino since last fall and it may last until the coming fall," said Edwards. "This affects weather patterns. It usually gets to 60 degrees at least once in February but we haven't even come close this month."

An El Nino is a disruption of the ocean-atmosphere system in the Tropical Pacific Ocean having important consequences for weather and climate around the globe. It is characterized by unusually warm ocean temperatures in the Equatorial Pacific, as opposed to La Niņa, which characterized by unusually cold ocean temperatures. It has important consequences for weather around the globe.

Among these consequences is an increased rainfall across the southern tier of the US and in Peru, which has caused destructive flooding, and drought in the West Pacific, sometimes associated with devastating brush fires in Australia.

"Last year the US also saw an El Nino season and in central Indiana it was a lean year for big weather events," added Ryan who talked about an EF3 tornado in Lawrence county in March 2009, a May 30 super cell in southern Indianapolis, June 2 storm in Northeastern Marion County and Fishers with baseball sized hail and an EF1 storm in Eminence in August.

Ryan explained the importance of wind speed, size of hail, shape of cloud formations, up and down drafts as well as any rotation in the weather cell.

In order for a thunderstorm to form, it needs moisture, warm air that can rise rapidly and "lift," which is a cold or warm front that is capable of lifting air.

Tornadoes form when a change in wind direction and an increase in wind speed creates a horizontal spinning effect. Rising air within the thunderstorm updraft tilts the rotating air from horizontal to vertical. This rotation extends through much of the storm and this is where tornadoes form.

Tornadoes are ranked by a scale called the Enhanced Fujita Scale and include the wind speeds. An EF0 has winds from 65-85 miles per hour. An EF1 has winds from 86-110 mph. An EF2 is 111-135 mph and an EF3 is 136-165. An EF4 is 166-200 mph and an EF5 has winds over 200 mph

In the United States there is an average of 1,200 tornadoes a year, causing 70 fatalities and 1,500 injuries nationwide. More statistics about tornadoes can be found at www.spc.noaa.gov

"Tornado season in Indiana generally starts in March when we see the most activity. It peaks in late May or June and there is a second peak in October," said Edwards.

He says that Indiana hasn't seen Class 4 or 5 tornadoes for a number of years.

"We have seen class 2 or 3 storms in early June," added Edwards. He has spotted 17 tornadoes, including five the NWS didn't know about in the more than 20 years he has been a weather spotter.

For other upcoming spotter training sessions in nearby counties, see weather.gov/ind.

Information gathered by storm chasers is sent to the National Weather Service by email or phone.

The class also covered the dangers of flooding and lightning as well as the importance of staying safe for spotters.

"More people are killed in floods and flash floods than any other natural disaster. Most of those occur in vehicles," said Ryan.

The impacts of floods vary locally. Categories for floods include minor, moderate and major and can be caused by rivers, tropical cyclones or flash floods. They can also occur quickly such as a flash flood that involves fast rising water in a low level area. They can occur in areas adjacent to a stream or arroyo, due to heavy rain, dam breaks, levee failure, rapid snowmelt or ice jams.

Additionally heavy rain falling on steep terrain can weaken soil and cause debris flow, damaging homes, roads and property.

The NWS is always looking for help in spotting storms. They provide training like the session presented Thursday evening.

For information about NWS go to the Web site at www.weather.gov/ind

Anyone interested in helping spot storms in Putnam County can call Edwards at 765-720-8650. Training will be provided.

Weather information can be found on the Internet at www.wrh.noaa.gov or www.nws.noaa.gov.

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