La Niña may cause warmer winter for southwest Colo.

MONTROSE — La Niña's influence on southwest Colorado ski resorts may result in less snowfall than normal, said Jim Pringle, a meteorologist with the National Weather Service in Grand Junction.

"It looks like it could be an interesting winter," Pringle said. "La Niña is gonna be a little stronger than what was indicated even a month ago. The stronger a pattern is, the greater the confidence that these events with above and below normal (conditions) will occur."

Last year there was a moderate El Niño pattern through winter months. El Niño refers to an event in which sea surface temperatures in the eastern tropical Pacific Ocean are above normal. La Niña, also known as "El Viejo," occurs when such ocean temperatures are below normal.

"Sea surface temperature patterns influence jet stream flows and jet stream flows drive storm tracks," Pringle said.

In the case of La Niña, the jet stream tends to fall through the Pacific Northwest. This could result in above-average snowfall through areas including the Great Lakes and Northern Rockies. Steamboat Springs appears likely to receive above-average snow this winter, he said.

"La Niña has been closer to above-normal North and below-normal South trends," Pringle said with regard to snow conditions.

Snowfall in the San Juans could be average or a bit below normal. The National Weather Service predicts La Niña's effect on New Mexico and Arizona to be much more apparent, with less precipitation and higher than average temperatures.

Pringle said it's possible to have transitions through the winter.

"Even in a year where you would anticipate below normal precipitation, you can't say for sure," he said. "As much as people would like to say it won't happen this year, you can't rule out that possibility."

In other seasonal news, Governor Bill Ritter proclaimed this week as "Colorado Winter Weather Preparedness Week."

The weather service encourages residents to beware of the myriad of dangers associated with the season.  

"While the attention of most people is focused on expected snow accumulation before a storm arrives, many ignore the life threatening combination of extreme cold and strong wind which often develops after the storm passes," according to a weather service press release.

A wind chill index factors wind speed with temperature to determine the weather's effect on one's body heat.

"A temperature of minus 5 degrees occurring with a 20 mph wind gives a wind chill near minus 30 degrees. This means that your body will lose heat at the same rate as it would if the air temperature were minus 30 degrees with no wind," according to the press release.

Hypothermia is the most common cause of winter weather-related fatalities.