Southwest Colorado is expected to see steady precipitation through Wednesday, according to the National Weather Service.
Forecast models show the area receiving between 13 and 25 inches of new snow between Friday and the middle of next week, reports NWS meteorologist Joe Ramey.
"It looks persistent for quite a while with back-to-back storms," he said.
The NWS has issued a winter storm watch for southwest Colorado beginning Friday at 6 a.m. and lasting until Monday at 8 p.m.
On Friday, the first storm hits in Cortez, bringing showers turning to snow overnight. Lower elevations like Cortez and Durango are right on the snow-rain line over the weekend, Ramey said. Weekend daytime highs are expected to be at or above freezing.
A second colder storm rolls in on Monday and is expected to generate steady snow for Cortez and the San Juan mountains.
"The colder air should make it all snow all the time," Ramey said.
Last weekend's storm dropped 24 inches of snow in the Dolores region, and 12 inches in Cortez, according to local weather watchers. Telluride reported 29 inches from the last storm.
Local meteorologist Jim Andrus said the upcoming storm system is similar to one in 1967 that dropped 18 inches of snow in Cortez and seven feet of snow in Flagstaff, Az.
"A deep, low-pressure trough over the Southwest is setting up a strong storm flow over the Four Corners," Andrus said. "It is not a good travel weekend. The National Weather Service predicts Wolf Creek could receive up to 70 inches of new snow."
After so many dry weeks, what changed?
Ramey explained that a high-pressure ridge in the atmosphere above California had been persistently blocking storms from reaching southwest Colorado. Last week, the ridge moved westward over the Pacific, allowing storms to go around and dive into Colorado.
The added moisture is good news for the Dolores Basin snowpack, which feeds McPhee Reservoir during Spring runoff. Before last weekend's storm, the basin was one of the driest in the state.
Vernon Lamb, a technician for the Dolores Water Conservancy District that manages McPhee, reported that on Feb. 19, the Dolores Basin's snow-water equivalent was at 61 percent of the median for that day.
By Monday, Feb. 23, the snow-water equivalent had jumped to 67.2 percent.
"That is still pretty low, but it is a noticeable improvement," Lamb said.
DWCD calculates real-time snowpack data from six SNOTEL sites in the Dolores Basin positioned at El Diente, Lizard Head, Lone Cone, Scotch Creek and Sharkstooth.
Median averages are calculated based on historical data from the units since 1987, except Sharkstooth which was installed in 2005. A sixth SNOTEL, Black Mesa, is not added to the data mix because it was recently installed and does not have enough historical data for practical comparison.
SNOTEL devices have "pillows" that measure the weight of fresh snowfall then calculate the snow-water equivalent using a computer. Data is transmitted via satellite.
Despite the bump in snowfall, southwest Colorado's overall snowpack is still the lowest in the state. The combined snowpack for the San Miguel, Dolores, Animas, and San Juan watersheds is at 68 percent of normal, as of Feb. 25. The state average is 82 percent of normal for that day.
Multiple feet of new snow in the high country increased avalanche danger.
The Colorado Avalanche Information Center (CAIC) reports the avalanche danger for the San Juan mountain at "considerable" for near and above treeline.
The level is considered "dangerous," reports forecaster Josh Hirshberg, and requires cautious route-finding. Conservative decision making is essential.
"This is one of the most extensive avalanche cycles of the winter," he wrote. "Current observation show significant slab avalanche activity that will likely be a serious problem with the next storm."
On Monday Feb. 23, an avalanche in the Peterson Slide north of Rico flowed onto CO. 145, confirmed Nancy Shanks, a spokesperson for CDOT.
"It was three feet deep at its center, and held up traffic for a half hour while crews cleared it away," she said.
CDOT works with the CAIC to conduct avalanche control work to prevent large avalanches from hitting the highway.
Also on Feb. 23, a skier died in a backcountry avalanche near the Aspen ski resort in an area known as Ophir Gulch. He is the third avalanche fatality for the 2014-15 winter season.
jmimiaga@cortezjournal.com
