Eye On The Storm
The following report comes on the heels of CBS4’s half hour weather special titled “Eye on the Storm,” which aired in Spring 2013. Watch all the videos from the special in the video clips below.
DENVER (CBS4) – Colorado can be a land of extremes when it comes to weather, with radical temperature swings and sudden storms.
The topography and elevation play a role in those extremes, creating paralyzing blizzards, devastating tornadoes and deadly lightning and flash flooding.
“Colorado is the highest contiguous state in the country with an average elevation of 6,800 feet,” explained meteorologist Dave Aguilera.
Aguilera said Denver sits in a river valley with high ground to the west, east and north. That means when weather systems like cold arctic air from the north and warm moist air from the Gulf of Mexico collide here, they can stay here.
In some cases that creates a day of heavy and blizzard conditions, other times you get violent weather like thunderstorms and tornadoes.
When that warm moist air blows in across the plains, cool air from the mountains forces it up. That’s the catalyst for sudden downpours, lightning and hail.
“Water behaves differently when it’s suspended in air,” Justin McHeffey explained. “It doesn’t freeze at 32 degrees, it freezes closer to 10 degrees.”
That superchilled but unfrozen water contributes to both hail and lightning. When it hits any other object in the air — like ice — it immediately freezes. With strong winds tossing it around, the newly created hailstone gets bigger until it’s simply too heavy to remain in the air.
“Ice particles have a positive charge, liquid water has a negative charge,” McHeffey said. “The opposing charges produce an electrical current within the cloud creating a flash of lightning. That cloud-to-cloud lightning does not pose a safety risk, but when a charge forms between the cloud base and the ground, dangerous lightning strikes hit the Earth’s surface with a flash hotter than the surface of the sun.”
And dangerous lightning and thunderstorms often spawn tornadoes born of their super cells.
Once more, it’s about the warm air hitting that cold air and being forced up.
“This can create wind shear or winds flowing in different directions,” explained Ed Greene, “building up a rotating column of air.
“The higher the storm, the stronger the drafts, making for a tighter and faster spin in the storm. The combination of intense up and down drafts create what is called a funnel cloud. When that cloud tilts to touch the ground, it officially becomes a tornado.”
The strength of tornadoes vary and are ranked on the Fujita scale from zero to five. Colorado is on the western edge of the nation’s “Tornado Alley” and has had tornadoes in any month and at almost any altitude.
The second highest tornado ever recorded in the United States touched down on Mount Evans at 11,000 feet in 2012.
The super cells that create those tornadoes and thunderstorms can also lead to flash flooding, but one of the most distressing weather problems plaguing Colorado right now is drought.
About 80 percent of the water in reservoirs which supply the Front Range and Eastern Plains comes from the snowpack.
In the 1990s, the weather turned drier in Colorado. In March, Denver Water, which controls much of the water in reservoirs declared a Stage 2 drought and put the strictest watering restrictions in place in a decade.
“Like tornadoes, drought has its own classification system,” Lauren Whitney explained. “It’s ranked from D-zero to D-4 with the levels showing how crops are affected.
“At zero level we’re going into or coming out of a drought. With the D2 or severe drought, you can expect crop losses and those water restrictions.”
And drought means conditions are ripe for wildfires. With tinder dry conditions, and many forested areas ravaged pine beetle, even the tiniest spark can lead to massive, destructive wildfires.
In 2012, a dry lightning strike started the High Park Fire west of Fort Collins, which burned more than 87,000 acres before it was controlled. Humans are blamed for starting the Waldo Canyon Fire just days later.
And when dry thunderstorms kicked up strong winds on June 26, the flames jumped firelines and destroyed the Mountain Shadows neighborhood.
That same rugged terrain and increase in altitude that helps create Colorado’s extreme weather also makes it tough to fight those fires, proving just how inter-related all of Colorado’s weather and geography really is.
- Written for CBSDenver.com by Raetta Holdman, “Eye On The Storm” show producer