Warming raises scientists’ concerns

By Launce Rake

Tuesday, Jan. 3, 2006 | 7:41 a.m.

According to the National Weather Service and the Western Climate Research Center, Las Vegas could at least tie the record for the warmest year, in average temperature, in recorded history. Other records:

Hottest overall month: July 2005, with an aver-age temperature of 95.3 degrees, beating the old record of 94.8 July 2003 by a half of a degree.

Wettest October on record: October 2005, with 1.45 inches, beating the old record of 1.22 inches set in October 1992.

Record of consecutive days with at least a trace of precipitation: 10, set February 17, beating nine set in 1978, 1952 and 1941.

Las Vegas enjoyed a break in a five-year drought in 2005 but endured record floods and later broiling heat in a year that had both casual and professional weather-watchers looking to the skies.

Along the way, the year tied the all-time hottest year for Southern Nevada. Some scientists said the weather is consistent with long-term climate changes that could continue to affect the West.

Local meteorologist John Adair of the National Weather Service said he doesn't worry about the long-term climate issues. He handles the weather, and he's had a lot to handle this year.

The year turned out to be the sixth-wettest in Las Vegas history.

"So far, we've had 7.36 inches (of rain) for the year," Adair said. "Normal is about 4.51, so we're well above it. "

Much of the rainfall came during January and February, storms that Adair said were "unprecedented" in their ferocity. The flooding from those storms destroyed stream banks and altered the course of rivers in Lincoln and northeastern Clark County.

Record heat made July the hottest month in Las Vegas history. On July 19, the mercury hit 117 degrees, tying the hottest temperature ever recorded at the city's official spot in the shade at McCarran International Airport.

Las Vegas also hit the all-time hottest average of 106 degrees for the same day, and set a new minimum high temperature for the day of 95 degrees.

According to preliminary numbers from the National Weather Service and the Western Regional Climate Center in Reno, the July heat wave helped lift the overall average for the year to 70 degrees, tying 2003's record-setting average for the year.

Kelly Redmond, a climatologist with the Western Regional Climate Center, was one of about 75 who gathered at a conference called by the Southern Nevada Water Authority and national environmental group Natural Resources Defense Council to look at climate changes affecting the West.

The conclusion of many of the scientists of the group was that the climate in the West would be particularly vulnerable to global change, which they believe is a product of human activity. Some climatologists predicted that the West will continue to receive about the same amount of precipitation it has averaged over the last century of record keeping, but there will be more rain and less snow as the temperature rises.

The weather, which is what people experience in a day, season or year, is "not inconsistent with those expectations," Redmond noted. "We're seeing about what we thought we would see."

By Dec. 29, the Colorado River upper basin -- a critical source of water for Las Vegas and the desert Southwest -- has received 113 percent of its average for the date. But the snowpack in the upper basin was 103 percent of normal.

"You can see that the precipitation is higher than the snow pack. That is all consistent with some of the expectations," Redmond said.

He said that in areas such as Montana, where normally this time of year snow would be flying, have instead seen steady rain.

Another trend this year is that the winter storms that are bringing snow and rain to the northern United States and Rocky Mountains are staying up north. The U.S. southern tier, including Southern Nevada, Arizona and, further east, New Mexico, Texas and Oklahoma, are missing out.

Redmond said that's contributing to the bruising drought in Texas and Oklahoma that has brought wildfires that have destroyed life and property.

The study of climate in the West comes as scientists are working with increasingly detailed -- and validated -- models of global climate change, including the Pacific and Atlantic oceans. Redmond said those studies need to continue, to prove or disprove theories of what is happening.

"Are these harbingers of change, or is this part of natural variation?"

Tracy Bower, a spokeswoman with the Southern Nevada Water Authority, said her agency also has a stake in understanding climate trends. Bower reminded the public that winter watering rules are still in effect for irrigation. She also noted that people's response to the weather can help conserve water in this time of shortage.