Weld County twister packed an unusual punch

The tornado that carved a path through Weld County on Thursday marked a deadly, if abnormal, introduction to the tornado season in Colorado.

Every year, dozens of twisters touch down across the state, but few wield the intensity of the one that sawed through Windsor and hit three other communities in north-central Colorado, peeling rooftops, cutting power and leaving one person dead.

"It's kind of a wake-up call that, yes, tornadoes can occur, they can be big, they can be fatal and they can be near the Front Range, so don't take them for granted," said Nolan Doesken, the state climatologist at Colorado State University in Fort Collins.

Last year, on March 28, a tornado packing winds up to 165 mph swept through the southeastern Colorado town of Holly, killing a mother of two.

Before that, the last time a fatal tornado struck Colorado was in 1960, in Sedgwick County.

Conditions in Colorado are favorable for small, short-lived tornadoes but rarely produce the kind of twisters seen in the country's "tornado alley," which cuts a volatile swath from west Texas to the Ohio River valley.

Part of the reason, experts say, is that the Rocky Mountains help interrupt the weather patterns needed to trigger and sustain violent storms.

Another is that Colorado receives less of the warm, humid air from the Gulf of Mexico that can fuel catastrophic tornadoes in parts of Texas and the Midwest.

"First and foremost, it's harder to form a stronger storm than it is a weaker storm," said Joe Ceru, a meteorologist with the National Weather Service in Pueblo.

Tornadoes in Colorado typically begin forming in May and continue through late June, though they have been spotted as early as March and as late as early October, Doesken said.

The National Weather Service in Pueblo reported 162 tornadoes in its coverage area between 1995 and 2007, including 16 in El Paso County. Of the region's total, 136 were Category 0 storms on the Enhanced Fujita Scale, the weakest on a scale of 5. Category 0 storms carry sustained gusts of 65 mph to 85 mph.

Eighteen were Category 1 tornadoes, with gusts up to 110 mph, and six were Category 2, gusting up to 135 mph. Just two were Category 3 tornadoes, packing the ferocity of the Holly tornado with gusts up to 165 mph.

The more powerful of the tornadoes touched down over the plains, far from the mountains that break up the most volatile weather patterns. But that doesn't mean that residents of the Front Range are free from risk.

"A tornado is a tornado," Doesken said. "Even a Fujita 0 - if you're in the way, it can be a bad day for you."

The Pueblo office oversees 21 counties in southeastern and south-central Colorado, ranging from Kiowa County to the northeast, Baca County to the southeast, Conejos County to the southwest and Lake County to the northwest.

CONTACT THE WRITER: 636-0366 or lance.benzel@gazette.com