A storm is expected to bring cooler temperatures, moisture and snow to the San Juan Mountains early next week in Southwest Colorado. Meanwhile, forecasts indicate a rare weather phenomenon called a “triple dip La Niña,” in which a La Niña winter occurs three years in a row, could occur this year.
Brianna Bealo, meteorologist at the National Weather Service in Grand Junction, said anywhere from 6 inches to 10 inches or more of snow could fall in the San Juan Mountains, although residents of the valley floors shouldn’t expect much if any snowfall.
High temperatures are expected to drop to the low- to mid-50s next week, and overnight lows could fall to the upper-teens to low-20s, she said. Sunday night into Monday morning is likely to be the coldest night next week.
So far, the second half of October has been unseasonably warm. Average high temperatures are in the low- to mid-60s this time of year, but this year’s daily highs have been closer to 70 degrees, she said.
Even more atypical is the chance of having a third La Niña winter in a row. If NWS forecasts are accurate, this winter will mark the third triple dip La Niña since 1950, Bealo said.
La Niña is one side of a two-part weather pattern involving the abnormal warming and cooling of the Pacific Ocean, she said. With El Niño, the waters warm. During a La Niña cycle, waters become abnormally colder. The temperature of the ocean then impacts weather conditions over the whole Northern Hemisphere, and the United States in particular.
La Niña winters are typically accompanied by drier and warmer weather conditions in southern Colorado, she said. Northern Colorado and other northern states typically experience cooler and wetter conditions.
She said weather conditions this October being warmer and drier than average is a “hallmark” of La Niña winters.
Meteorologists at the NWS Grand Junction office are conducting research that shows stronger monsoon conditions take shape toward the end of a La Niña cycle, Bealo said. But with a triple dip La Niña, it’s hard to determine if monsoonal activity this summer is related to the weather pattern.