Jun 12, 2008 1:00 pm US/Mountain
Aguilera: Tornado That Hit Windsor Was A Mile Wide
Tornado Touched Down After Noon On May 22, Traveled 34 Miles
WINDSOR, Colo. (CBS4) ―
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An image from YouReport of the funnel cloud, contributed by Dawn Dressel of Lakewood (her daughter took the photo)
CBS
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Sarah Fintelmann of Evans shared this photo on YouReport of the tornado at about noon looking to the north from east of Miliken and south of Gilcrest.
CBS
After more than two weeks of analysis the National Weather Service determined that the tornado that hit Windsor and other Weld County communities on May 22 was an E-F3, meaning winds were between 136 and 165 mph.
The tornado, which was a mile wide at times, tore roofs off buildings, flipped freight cars and tractor trailers and killed one person.
Reports of severe weather began rolling in a little after 11 a.m. Several northern Colorado towns were pounded with golf ball sized hail in areas near the tornado.
The hardest hit area was Windsor, where the tornado ripped through the town just a few minutes before noon. Nearly 80 homes there were completely destroyed and more than 700 others were damaged.
It's estimated that the tornado stayed on the ground for 34 miles, causing damage in all the communities along its path, from Platteville to Gilcrest, Milliken, Windsor and west Greeley.
Weld County has a highest number of reported tornadoes than any other county in Colorado. The National Weather Service Denver office says that since 1950 there have been a total of 20 tornadoes of F3 and higher ratings within Colorado.
The Windsor tornado was the second F3 tornado reported in Weld County since 1950.
Weather Elements That Produced The Tornado
All the ingredients came together to produce the perfect set up for big super cell thunderstorms on May 22.
In the upper levels of the atmosphere a deep low pressure trough over the great basin, in the western U.S. helped to create a powerful southeast flow across eastern Colorado. This strong upper level flow helped to steer the storms in a northwesterly direction. This was unusual because typically our thunderstorms tend to travel in an easterly direction, be that northeast, east or southeast.
The second driving force behind the huge tornado producing thunderstorms was a cold front that moved through eastern Colorado Wednesday night, pumping up the moisture content in the eastern plains.
Early Thursday, a defined boundary set up in Weld County over into Lincoln County separating dry air from moist air; this boundary is called a dry line (or sometimes a "dew point line"). It was along this "dry line" where the thunderstorms formed and strengthened. The cold moist air pushing up into Weld County wedged up under the drier warmer air in the northern part of the county.
As the day went on a strong east-southeasterly wind developed, helping to add lift for the thunderstorms to feed off of. That wind direction also helped to push the big storms to the northwest, which is a rare direction for Colorado thunderstorms to go.
Here is a list of a few of the National Weather Service reports of hail and tornadoes across areas of northern Colorado Thursday, with most of the reports from super cell storms in Weld County.
547 PM 1 inch(es) HAIL 4 E HAXTUN
154 PM 1 inch(es) HAIL 1 SW BERTHOUD
147 PM 2 inch(es) HAIL 1 NW WINDSOR
104 PM 1 inch(es) HAIL WELLINGTON
1251 PM 1 inch(es) HAIL LOVELAND
1228 PM 1.25 inch(es) HAIL N LONGMONT
1216 PM 2 inch(es) HAIL 3 E LONGMONT
1156 AM 2.75 inch(es) HAIL WINDSOR
1232 PM TORNADO 4 SW DACONO
1202 PM TORNADO 8 W GREELEY
DIRECT HIT ON STATE FARM BUILDING. CARS TOSSED OFF OF
ROAD. TREES DOWN. SWIFT COMPANY ROOF TORN OFF. TORNADO
3/4 TO 1 MILE WIDE
1157 AM TORNADO WINDSOR
1140 AM TORNADO 3 E MILLIKEN
1132 AM TORNADO GILCREST
1127 AM TORNADO PLATTEVILLE
1126 AM TORNADO 2 SW MILTON RESERVOIR
The difference between a tornado watch and a tornado warning Tornado Watch: Is issued when conditions are just right for tornadoes to develop. It does not mean tornadoes are imminent, just that you should be aware that the possibility is there. When you hear or see that a watch is in effect, you should keep an eye and ear tuned to television or radio so you know what is going on with the weather.
Tornado Warning: Is issued when a tornado has been spotted, or indicated on Doppler radar. When a tornado warning is issued for your town or county you should take immediate safety precautions.
What is a Tornado?A tornado is a rapidly rotating column of air dropping from a strong thunderstorm to the ground. That thunderstorm cloud is known as a cumulonimbus cloud.
What causes a Tornado?Inside a cumulonimbus cloud or thunderstorm, you have updrafts and downdrafts. Warm rises up into the thunderstorm and cold air sinks down in the thunderstorm.
Now all air masses have a certain amount of spin, but, the updrafts and downdrafts in a thunderstorm increase that spin inside the storm. This motion creates a horizontal rotating column of air. The rising and dropping air tilt that column vertically and if that column of air extends to touch the ground, Bingo, you have a tornado!
The technical term for this process is called "Conservation of Angular Momentum." Have you ever seen an ice skater doing spins on the ice? When the skater pulls their arms in close to their body, they can spin faster and faster.
With a thunderstorm, the tighter the spinning air goes, the stronger the rotating column of air gets.
How long can a tornado last?Some twisters may last only for a couple of minutes and are on the ground for a few feet to a few miles. While some can last several minutes to several hours and travel from a few miles to more than a hundred miles. A few of these huge tornadoes may have paths of destruction that are a mile wide.
When do tornadoes occur?In Colorado, primetime for tornadoes is from mid May through mid August. Colorado twisters have been reported in 9 out of 12 months of the year.
The big month for tornadoes is June. Through the years most of the recorded tornadoes in our state have popped up in the month of June.
Most of our tornadoes happen between 1pm and 9 pm. In fact, 88 percent of them occur during this time period. And over half of all twisters threaten between 3pm and 6 pm.
If you break it down by county, Weld County in Northeast Colorado is the big winner or loser (depending on how you look at it) in number of tornadoes. In fact, Weld County on average has one of the biggest numbers of tornadoes across the country! The reason for that is primarily due to Weld counties size. It is 2 to 3 times larger than most counties in the United States.
Where are Tornadoes most likely to form?Tornadoes can occur anywhere in the state of Colorado, but, most of them develop in Eastern Colorado. Most of those occur east of Interstate 25.
Twisters have been reported in every state in the United States. But, if we look at the nation as a whole, the bulk of tornado producing thunderstorms hit an area that meteorologist call "Tornado Alley." This is an area of land in the nation's midsection that is clobbered by more tornadoes than anyplace else in the world!
This area runs from North Texas through Oklahoma, Kansas, Missouri, and Ohio. That's not to say all tornadoes occur in this area. But, a large number of them do. Other areas that pick up a lot of tornadoes include many southern states like Mississippi, Alabama, Georgia and Florida.
How is the Strength of a Tornado measured?Meteorologists use a scale called the "Enhanced F-scale" to measure the power of a tornado. It is a scale that is based upon how much damage any given tornado produces.
*** Important note about F-scale winds: These precise wind speed numbers are actually guesses and have never been scientifically verified. Different wind speeds may cause similar looking damage from place to place. Even from building to building. A new "Enhanced F-scale" will be implemented in February 2007.
The Enhanced F-scale replaced the old Fujita scale, (F-scale), which is named after Professor T. Theodore Fujita, a pioneer in the study fo tornadoes. The new Enhanced F-scale gives more detailed information about damage and winds.
Click here to see the Fujita Scale.
(© 2009 CBS Broadcasting Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)
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