Colorado wildfires ruthlessly march on

An earlier version of this story misstated the size of the High Park wildfire.

By RJ Sangosti, Denver Post via AP

The Waldo Canyon blaze destroyed much of the Mountain Shadows subdivision in Colorado Springs.

By RJ Sangosti, Denver Post via AP

The Waldo Canyon blaze destroyed much of the Mountain Shadows subdivision in Colorado Springs.

FORT COLLINS, Colo. — As flames from a destructive, uncontrolled wildfire licked the southwestern end of their campus, more than 1,000 cadets arrived at the Air Force Academy in Colorado Springs on Thursday to begin their studies.

Housing units in the southern part of the 18,500-acre academy had been evacuated Tuesday as a precaution, and a 10-acre fire briefly flared in that area Wednesday, academy spokesman Harry Lundy said.

Processing of the 1,045 "doolies," as freshmen are known, went smoothly at the north end of campus despite the looming Waldo Canyon wildfire. Evacuees are being housed at nearby military facilities, he said.

President Barack Obama will tour wildfire-stricken Colorado Friday, where thousands of people have been displaced by out-of-control blazes.

The president's visit comes as about half of the active federal firefighting resources are in Colorado, where extremely hot and dry conditions have triggered several large wildfires during the last month.

Nationally, firefighters were battling 41 major fires Thursday, the National Interagency Fire Center reported. Hot weather, lightning strikes and dry, unpredictable winds pushed the number of fires to 242, 11 of them defined as large by the fire center. The definition varies depending on terrain and danger to human habitation, said Coleen Decker at the National Interagency Fire Center in Boise.

There were 2,864 firefighters at work, aided by 107 helicopters dumping fire retardant and water. The firefighting cost for the year so far: $119.8 million, according to the center.

The weekend will bring little relief to Colorado Springs, Decker said. Temperatures might dip slightly from 103 degrees to 100, she said. Flame-spreading winds are forecast to be weaker, but thunderstorms could light new fires .

Colorado, with three major blazes, has the worst of it. The Waldo Canyon wildfire has burned more than 28 square miles, including neighborhoods in Colorado Springs. Mayor Steve Bach said 346 homes have been incinerated, making it the most destructive fire in state history.

Northwest of Fort Collins, firefighters said they were getting ahead of the 136-square-mile High Park fire that killed a woman and destroyed at least 257 homes after being sparked by lighting June 9. The fire was 75% contained and could be under control early next week, said Jim Toomey of the Larimer County sheriff's office.

Near Boulder, containment of the Flagstaff wildfire west of the city grew to 30%. The fire burned 300 acres, but 26 families that were evacuated Tuesday when the fire began were allowed back Thursday evening.

The fire was "one ridge away from impacting the city," said Dan Rowland, a spokesman for the Flagstaff wildfire management team. "That would have been a game-changer."

"We are on heavy alert going forward," he said. "We're watching it every day."

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Hughes also reports for the Fort Collins Coloradoan. Weise reported from San Francisco.Contributing: Associated Press

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Breaking Down the March Tornado Outbreak

New images from the nation's Storm Prediction Center show how much of the South and Midwest were affected by the severe weather and tornadoes on Friday (March 2).

An entire month's worth of tornadoes struck across parts of the country from March 2 into the morning of March 3. The Storm Prediction Center received 81 reports of tornadoes on March 2, according to data filtered to remove duplicate reports of tornadoes. For the entire month of March, the 10-year average number of tornadoes is 87, according to the Weather Channel's severe weather expert Greg Forbes. The National Weather Service's storm survey teams have not yet confirmed the tornado reports, so these numbers could change. But if the numbers hold, the outbreak could go down as the largest single-day outbreak in March history.

In 2006, the biggest March outbreak saw 105 tornadoes from March 9 to 13. March 12 of that outbreak saw 62 confirmed tornadoes. Yesterday's outbreak could top that total.

The unfiltered storm reports in one new image show that the Storm Prediction Center received 128 tornado reports on March 2.

To see how the March 2 outbreak compared with the April 27, 2011, outbreak — the largest tornado outbreak in recorded history — meteorologists at the Storm Prediction Center compared the tornado and severe weather warnings issued during those outbreaks (image below). On the March 2 outbreak, the area of warning covered nearly 500,000 square miles (1.3 million square kilometers).

During the April 27 outbreak, the area of warning covered more than 1 million square miles (2.6 million square km).The National Oceanic and Atmospheric Administration created a map of areas with high rotational velocity — an important ingredient for forming tornadoes — using data from NOAA's network of NEXRAD radar installations, processed by the National Severe Storms Laboratory in Norman, Okla. By examining these images, forecasters can determine the approximate tracks of so-called supercells, which feature strong rotation and are known for producing tornadoes. Some of these supercells had rotational velocity up to 180 mph (290 kph), and so their signature stands out from the surrounding storm areas. Features such as these are watched carefully for possible tornado outbreaks.

An from NOAA's Suomi NPP VIIRS instrument shows the overshooting cloud tops and intense storms associated with March 2 tornado outbreak. The imagery was acquired over Illinois, Indiana, Ohio and Kentucky. Polar-orbiting satellites track the subtle changes in the environment that can trigger potentially deadly weather conditions, from tornadoes to tropical storms. Current operational POES data was critical for issuing watches and advisories days in advance of this outbreak.

You can follow OurAmazingPlanet staff writer Brett Israel on Twitter: @btisrael. Follow OurAmazingPlanet for the latest in Earth science and exploration news on Twitter @OAPlanet and on Facebook.

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