Saturday, September 06, 2014

Colorado peaks dusted with snow, but forecasts show extended summer

#Breckenridge, Colorado.

Tim Finnigan / Arapahoe Basin Ski Area

Breckenridge residents who woke up to snow-covered peaks Friday morning might be wondering what season it is.
“It’s really not the beginning of winter yet,” said Todd Dankers, meteorologist with the National Weather Service office in Boulder, and the folks clinging to summer are still winning over the ones craving powder.
The weather system Summit County experienced Thursday night was a combination of moisture coming from the south and a cold front out of the north, he said. The precipitation was consistent with the late-summer monsoon pattern, while autumn and winter storms typically come from Canada and the Pacific Northwest.
Satellite imaging showed the system that produced Friday morning’s dusting stretching into Mexico, Dankers said. Summit’s highest mountains are simply tall enough to produce snow even with subtropical moisture.
At Arapahoe Basin Ski Area, employees shared photos Friday of snow at the resort’s summit and on runs leading to the midmountain restaurant in hopes of getting skiers and riders excited for the upcoming season.
The resort, which typically opens before the rest in the Colorado mountains, started making snow last year on Sept. 28, and the first significant snowfall occurred a week or so before that, said Adrienne Saia Isaac, communications manager.
The latest dusting is one of a few the tallest mountains around Summit have seen in the last couple weeks.
The forecast going into next week calls for warmer weather and the chance of afternoon thunderstorms typical of late summer, but from here on out, every passing storm could bring dustings, and the line of white likely will move farther down the mountains each time, said Nolan Doesken, state climatologist at Colorado State University.
If the rain in Summit over the last month seemed above average, that’s because it was a little wetter than normal in the High Country, Dankers said.
Other parts of the state saw much heavier than usual precipitation last month, with areas in the northeastern plains receiving a rare 7 to 8 inches of rain.
This summer also has been on the cool side, Dankers said, and soon the season might feel like it’s lasting a little longer. In the latter half of September and early October, the region likely could see a large ridge swing through that would dry out the area.
Fall happens meteorologically speaking, Doesken said, “when you no longer have midday and afternoon cumulus clouds that have marked your weather for the whole summer.”
Summer’s vertically oriented, cauliflower-shaped clouds become flatter with wave formations in autumn, he said, and the most likely time of year for the weather to be totally clear, without a cloud in the sky, is around the end of September.
The feeling of fall and the word September, for many Coloradans, might bring to mind scenes from last year of catastrophic flooding in Boulder County and across the state. Dankers said he hasn’t seen any weather systems in the forecast similar to what created those emergency situations.
“Hopefully we won’t get a repeat of that,” he said. “The weather pattern today is nowhere like that pattern we had last year.”
Plus the entire week right before the flooding in Colorado was hot, Doesken said, which isn’t the case this year.
Looking to the forecast for the rest of winter, Dankers said, early September is a bit too soon to predict with much accuracy.
However, meteorologists have been watching the Pacific this summer in anticipation of the phenomenon known as El Niño.
Earlier in the summer, sea surface temperatures were indicating a strong chance of El Niño, which would have implications for the way snow distributes in the mountains.
In the last month or so, that situation changed and isn’t developing the way scientists expected, Dankers said, so they are now predicting a 60 percent chance of El Niño.
A strong El Niño would increase the chance of more snow than usual in the southern Colorado mountains, from Aspen into the San Juans, as long as the phenomenon doesn’t move too far south into Arizona and New Mexico. “Then even the San Juans get cheated out of snowfall.”
In the northern and central mountains, from Steamboat into Summit and Eagle counties, snow distribution would depend more on the kinds of storms that develop later in the winter.
The effect of a weaker El Niño, which is happening this year, Doesken said, is less clear cut.
“It’s by no means a guarantee of heavy snows for the northern Rockies,” he said. “That’s not the right logic for Summit County.”
Dankers said the last super-strong El Niño was in the winter of 1997-98, when an October snowstorm produced a couple feet of snow in Denver.
During El Niño years, he said, Colorado often sees singular storms that produce heavy snow while the rest of winter is drier with less evenly distributed snowfall. Dankers said people shouldn’t pin that pattern on El Niño, though.
“It’s a tricky thing to forecast these seasonal things,” he said. “When you get a good pattern, you go out and make the most of the snow and don’t worry about what produces it. You ski the stuff.”
Courtesy of the Summit Daily News.