From The Fort Collins Coloradoan (Jacy Marmaduke):
Fort Collins hasn’t seen measurable snow in 35 days. You can blame the abnormally long streak and recent short-sleeve weather on a familiar atmospheric phenomenon that has been unusually stubborn: a high-pressure ridge crouching over the western third of the United States.
That ridge might finally leave us for the eastern Pacific Ocean this weekend, which could mean cooler weather and a dash of snow.
The ridge is nothing new for the Western states. It’s the reason late summer and early fall are often warm and dry in Fort Collins. Like a giant dome stationed over Colorado, the ridge fends off cold fronts and moisture and usually clears out by early October, said National Weather Service meteorologist Todd Dankers.
Except this year it won’t budge.
“That’s what’s abnormal,” Dankers said. “Normally, you’re seeing more active weather as we move into winter patterns.”
The ridge has kept Fort Collins pretty much snow-free since Nov. 7, the last time the city got measurable snow. We’ve had three measurable snows this fall, but two of them were in October. In all, we’ve received less than half the normal amount of snow between Oct. 1 and Dec. 11 — 6.2 inches compared with a normal amount of 15.4 inches, according to 1981-2010 averages from the Colorado Climate Center’s weather station at Colorado State University.
The ridge is also the culprit of this month’s surprisingly warm highs. Through Dec. 12, nine days of December have seen high temperatures of 55 F or more. Normal highs for early December are in the lower 40s, like what we saw for a spell last week.
November was Fort Collins’ sixth-warmest on record. Highs regularly defied historic normals by 10 to 20 degrees, reaching a peak of 77 degrees Nov. 27.
Why isn’t the ridge moving? It’s hard to say, Dankers said.
It’s similarly hard to say whether La Nina, or the cooling of waters in the equatorial Pacific, has anything to do with recent conditions. Dankers added that La Nina is still developing and is “rather weak right now.”
As of Tuesday, 10 snowpack monitoring sites hit record lows for this time of year, according to the Colorado Climate Center. Another six locations had the second-lowest snowpack levels ever recorded this time of year.
Several of those records and near-records are in the Colorado River and South Platte River basins. On Tuesday, snowpack in the South Platte and Colorado river basins sat at 76 percent and 62 percent of the averages for this time of year, respectively, according to data from the Natural Resources Conservation Service.
From KOAA.com (Sam Schreier):
Statewide we have almost half of the normal snow for this time of year. The San Miguel, Dolores, Animas and San Juan River areas are some of the worst spots with 24% (nearly 1/4) of the average snow water equivalent. The Arkansas River valley, including cities like Colorado Springs and Pueblo, is slightly better off but still far below average with only 61% of the normal snow water equivalent…
This is fitting the La Nina pattern that tends to give southern Colorado dry, drought filled winters. It’s very likely we’ll see below average snowfall through the rest of the winter.