Colorado's Unusually Dry Weather, Explained

COLORADO — Crews have been busy battling wildfires near Idaho Springs, Ken Caryl Valley, Estes Park and other Colorado areas over the past several weeks, as the dry weather continues in our state.

Before this year, the latest first measurable snowfall on record in Denver was Nov. 21, way back in 1934. With no snow since April 22, this is the third-longest stretch the city has gone without it.

In Boulder, meteorologist Bob Henson enjoyed a rare December bike ride on Thursday.

Still, "there's a lot of angst about the lack of snow," he said. "It puts you in a psychic quandary. You enjoy the warm weather while keeping in mind it's not good for Earth to be warming."

On Thursday, 65 weather stations across the nation set record high temperature marks for Dec. 2.

Meteorologists attribute the latest batch of record-shattering weather extremes to a halted jet stream and the effects of a La Nina weather pattern from cooling waters in the equatorial Pacific.

The jet stream — the river of air that moves weather from west to east on a rollercoaster-like path — has just been stuck. That means low pressure on one part of the stream is bringing rain to the Pacific Northwest, while high pressure hovering over about two-thirds of the nation produces dry and warmer weather, said Brian Hurley, a senior meteorologist at the National Weather Service's Weather Prediction Center in College Park, Maryland.

If the jet stream moves more or bends differently, rain and other extreme weather won't be as concentrated, Hurley said.

This is a typical weather pattern with a natural La Nina weather oscillation, he said. The flip side of El Nino, a La Nina is a cooling of parts of the central Pacific Ocean that changes weather patterns across the globe. La Ninas tend to bring more rain to the Pacific Northwest and make the South drier and warmer.

These bouts of extreme weather happen more frequently as the world warms, said meteorologist Jeff Masters, founder of Weather Underground who now works at Yale Climate Connections. But scientists haven't done the required study to attribute these events to human-caused climate change.

The Associated Press contributed to this report.