Hwy 550 corridor/RMP ~ SWE ~ 2/15/19 @ 17:30

potent storm, high PI.  Most of this fell Thursday night.  Had a big natural cycle in highway paths.  All of the usual suspects crossed the road sometime Thursday night or Friday morning.   Red  reopen at 9:15  last night.

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Monument: 13″/1.25″

RMP 18″/1.85″

Molas 20″/2.25″

Coal Bank 25″/2.7″

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Avalanche! Life and death by degrees

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By Eric Ming, Watch Contributor

 

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The Battleship heading on a collision course with Hwy. 550.  Jonathan Thompson photo

On Jan. 5, a skier participating in an avalanche course in Senator Beck Basin on Red Mountain Pass was buried under three meters of avalanche debris and killed.

Two in-bounds skiers were caught in a slide on Kachina Peak, at Taos Ski Valley, on Jan. 17. Both were trapped under the snow for around 20 minutes and eventually died.

On Jan. 21, a skier in the Ashcroft area, near Aspen, was buried on a slope near where he had been skiing for the previous two days.

The Colorado Avalanche Information Center (CAIC) listed 193 avalanches in 10 days last month, between Jan. 19-29 — and those were just the slides that were reported.

“So far this season, CAIC has recorded 54 people caught in avalanches,” the state’s forecasters wrote on Jan. 25. “Nineteen people were partially buried (three of whom had their heads beneath the snow) and four were completely buried. Tragically, two of these accidents resulted in fatalities.”

By contrast, “On average in a single season, CAIC gets reports of 63 people caught in avalanches and six people die in avalanche accidents.”

“The numbers above are just the incidents we know about, and we’re only halfway through the season. Bottom line: We have dangerous snowpack conditions this year, and even if we inch across the line to Moderate danger, conditions will not be safe for the foreseeable future. Most avalanche accidents happen when the avalanche danger is rated MODERATE or CONSIDERABLE.”

By Feb. 1, the numbers went up again, and the CAIC documented three more people caught in avalanches. These are “impressive and scary” statistics, the forecasters wrote.

Nine out of every 10 avalanches is caused by a backcountry traveler, and this year’s cycle seems far fiercer than usual. Is it because there are more people out there than usual? Is this going to be the year that snow riders recall as extremely volatile and/or especially deadly?

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Jerry Roberts readies 50 lb. charges for helicopter mitigation.  Mark Rawstoned photo

Jerry Roberts has labored over 40 years in the San Juans forecasting weather and avalanches for various organizations including the Colorado Department of Transportation, CAIC, INSTAAR and many avalanche education programs. Based on statistics in stacks of yellow, Rite in the Rain notebooks that he kept each winter on snowpack and weather conditions, he said, “Only six years were stable as a Mormon marriage. The San Juans are a desert range, dry, with a shallow snowpack and few storms.”

Such characteristics make for what he calls a “conditionally unstable” snowpack.

“You can’t ski the San Juans aggressively. You might get away with it for awhile, based on dumb luck, but eventually you’ll get caught,” Roberts said. “Ask many of the locals who’ve been buried numerous times. Pick your posse carefully — not one filled with Type A personalities, but a group with a variety of personalities. Beware of the ‘Expert Halo’ trail boss. No one wants to be the timid one, but you should always speak up and question a decision in a group if you are uncomfortable.” Snowpacks have regional climate characteristics, and Colorado’s is known as a “Continental” snowpack. This type of snowpack tends to be shallow, with temperature gradients that create faceted, depth-hoar snow crystals — and can result in long-term, unstable layers often buried near the ground. A Continental snowpack is considered extremely capricious and unpredictable when it comes to skiing or boarding safely, and snow in the San Juans, in particular, is generally the sketchiest of the lot.

Ridgway resident Angela Hawse is the president of the American Mountain Guides Association, and a former forecaster for Telluride Helitrax. “We have the worst Continental snowpack anywhere,” Hawse said. She employs a conservative strategy in the San Juans. “Everyone has to be a forecaster,” she said. “The days of going along with the group, expecting someone else to be the leader and casually ignoring safety protocols and equipment, are no longer appropriate.”

Peter Lev is a contemporary of Roberts, having worked in Little Cottonwood Canyon, Utah, for the highway department, the Alta ski area, and as a forecaster and lead guide for Mike Wiegele’s helicopter operation in Canada.

“The Wasatch is pretty well known for lots of avalanches,” he said, “but Colorado takes the cake for its Continental snow climate. That’s why there are so many deaths here. And hazards exist frequently into spring. It doesn’t go away; it just goes into relaxed mode every so often.”

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A natural slide from mid-January crossed the Ophir Pass Road, near Red Mountain Pass. (Photo by Bill Liske)

INCREASING CROWDS,

Red Mountain Pass seems to have been discovered this year: the number of skiers appears to have increased, along with new huts and yurts that accommodate overnight skiers and those looking for guides and avalanche courses. Roberts recalled when three cars parked on the pass was a big day; now Red is going the way of Teton Pass in Wyoming and Berthoud Pass on the Front Range, with their backcountry crowds and all the complications that go with finding parking, to having groups skiing above you in hazardous places, to turning a potentially untracked paradise into a tracked up, ski-area-like wasteland.

Hawse views more people overnighting on Red as a numbers game, where there are “more people without experience, and there will be more incidents. But the culture of sharing (avalanche information) is changing in a positive way,” she added. “People’s willingness to send observations to online avalanche sites is going to prevent more accidents.”

Roberts observes that statistically, the number of “winter recreationists doubles every five years but avalanche fatality rates have remained flat for the last 20 years.”

The question is whether avalanche training will be enough, given the increasing crowds. We’ll see if that holds true.

Lev believes that the moon’s gravitational pull influences not only tides but also snowpacks — and that as a result, there is more tension in the layers of a snowpack at certain times than there is at others.

“Sometimes the snowpack’s more relaxed,” he said — and people can get by with skiing things that might not otherwise be safe.

By contrast, in conditions like we’ve had the past few weeks, he advises pulling back to “pet runs,” places that you know well and that are safe to ski.

A MATTER OF DEGREES

The slide on Jan. 21 that killed a skier south of Ashcroft happened on the third day of the trip. The group had been doing laps on a nearby slope with an angle of less than 30 degrees, according to a CAIC report. On Jan. 21, the skiers moved to a slightly steeper slope that tilted about 35 degrees. In a season with this much instability, those extra four or five degrees made all the difference, and a skier triggered a release 400-foot wide and 2-to-4-feet deep that ran 600 linear feet.

The angle of the slope that failed in Senator Beck Basin was between 32 and 34 degrees, according to the post accident assessment by the CAIC. The probability of a slope avalanching over 30 degrees goes up significantly, especially in seasons where there is buried weakness in a snowpack (and there is almost always some weakness).

The Utah Avalanche Center offers an online training program called Know Before You Go. In the section entitled “Get Out of Harm’s Way,” there is crucial information about angles and the importance of slope steepness. Statistically, most avalanches are triggered on slopes between 30 and 45 degrees. When the Ashcroft skier decided to transition from a northeast-facing slope below 30 degrees to a slope of 35 degrees, on a day where there had been an avalanche warning specific to northeast slopes, he was moving into a perfect storm.

For 25 years, Roberts taught snow science/avalanche courses to students from Prescott College.

“Avoid the hazards,” he said. “Avoid getting caught. Take the old man route back home. Good route finding will always serve you well, and is the most important skill you can develop for the winter mountains.”

Because snow and weather conditions vary, forecasters divide travel areas into zones. Colorado has 12. Lev considers avalanche forecasts “broad brush strokes.”

“We have to remember, there are hundreds of slopes out there that can behave differently,” he pointed out. As accurate as forecasts can be, there are still endless variations not only in big ski lines, but also on small slopes and terrain traps (features that can bury you just as easily). Roberts advises stepping aside from the group and making your own “environmental observations.” He calls the personal sphere that your inner snow safety specialist engages in “Nowcasting.” Use your “patroller’s legs” to feel  the snow density: is the slab collapsing/fracturing or for anything in your immediate surroundings that hints at instability. It’s all part of the package that makes for a safe day  in the mountains.

“Every year is a new experiment,” Roberts summed up. The snow depth is different, the wind is from an unexpected direction and the water content (CWE) varies from storm to storm. It is hard to standardize and make generalizations.

Hawse tells her winter clients, “This isn’t the place to ski the gnar.” They are encouraged to come back in spring if they want to ski bigger lines. She says her “Spidey sense gets up” when she is on slopes of about 33 degrees. When Hawse worked for Helitrax, and the slope had been mitigated with explosives, 35 degrees might have been OK to ski. But if the slope hasn’t had the shock of explosives, she said, she is going to ski lower angled terrain.

She also reads the full day’s forecast, and any hazards that may exist, on avalanche sites. “People don’t do a very good job of alerting properly to the yellow colored ‘Moderate’ rating on avalanche sites. They don’t even take the rating ‘Considerable’ seriously enough,” she said. Reading all the analysis is critical, she said — not just skimming the colors on the hazard tabs. You start to understand forecasting when you can put all the components together: weather, snowpack history and weaknesses, wind, slope angles and surrounding terrain.

Hawse also agrees with her mentor, Jerry Roberts, that “hasty pits” — quickly dug snowpits — are an effective way to assess conditions as you travel. They’re efficient, and can tell you a lot about how the snowpack is holding together. She keeps a probe clipped to her pack so it is readily at hand, and she can poke around in snow that she is unsure of. Although there are apps you can download on your phone that show a slope’s angle, Hawse uses a compass (an old LifeLink Slope Meter accomplishes the same thing).

All three skiers have spent decades managing avalanche risks for the safety of untold numbers of people, whether they were skiing and riding in hazardous mountain terrain or merely driving up Red Mountain Pass or Little Cottonwood Canyon. And they all have their own version of pulling back to Lev’s “pet slopes” — places with angles of 30 degrees and lower when things are unstable and risky.

“We are not done with this season — not even a chance,” Lev emphasized.

Roberts reiterated the words of the Buddha: “Kill the ego, kill the desire” when it comes to skiing or riding the big line that might kill you.

 

IF YOU GO

Before you leave the house, check out the Friends of the CAIC’s Instagram page, which has photos of recent slides (an education in and of itself).

Jerry Roberts has collated seemingly every relevant avalanche and weather related site in one place, with links to remote weather stations, road conditions, extended forecasts, jet stream, radar, infrared, SNOTEL, highway cameras and more at: therobertreport.net/weather-links-2/

State weather stations can be found here: avalanche.state.co.us/observations/weather-stations/.

The Utah Avalanche Center’s excellent online education program, ‘Know Before You Go,’ is free of charge. The videos they’ve produced offer a good sense of getting caught in a slide. Find both at utahavalanchecenter.org.

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A definition of a conditionally unstable snow pack from INSTAAR Occasional Paper
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January precipitation boosted snowpack ~ The Watch

Still, San Juan Mountains watersheds remain under ‘exceptional’ drought

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This map of snowpack in Colorado’s eight major river basins shows our area colored a relatively healthy yellow; last year at this time, it was an alarmist red. (Image courtesy of Natural Resources Conservation Service)

 

Because large snowbanks loom above many streets and because Telluride Ski Resort has reported 181 inches of snowfall so far this ski season, many locals assume the perilous drought that struck last winter has vanished. Not quite.

The eastern parts of San Miguel and Dolores counties, the southern part of Ouray County, and all of San Juan County are still experiencing “exceptional” drought, according to the United States Drought Monitor.

“We were in a very severe drought last year — a category D4 or exceptional drought, which is the most intense drought you can suffer — for quite a few months,” said Jimmy Fowler, a forecaster at the National Weather Service’s Grand Junction office, when the Daily Planet contacted him Friday afternoon. “It’s going to take a while for southwest Colorado to get out of a D4.”

The 2018 drought, Fowler added, was caused by “a high pressure system that set up on the West Coast and sent all the moisture away from Colorado, and that high pressure lasted through summer and produced a lackluster monsoon season,” resulting in the prolonged parch.

Precipitation that’s fallen from November through January has certainly helped Colorado as a whole: At the end of October, 13.64 percent of the state experienced D4 conditions but on Jan. 31 (Thursday) only 2.79 of the state suffered under that classification. Unfortunately, that 2.79 percent was largely centered in our area, known to drought watchers as the combined San Miguel, Dolores, Animas and San Juan rivers watershed, where mountain snowpack stood at 66 percent of normal, according to measurements taken Jan. 1.

That’s still much better than 2018, when those drainages claimed a snowpack a meager 35 percent of normal size. Indeed, southwest Colorado’s snowpack in 2019 has grown to 305 percent of what it was last year.

Snotel measuring stations around the state are checked on the first of each month, and February results were posted by the Natural Resources Conservation Service late Friday afternoon. The measurements presented more good news: Precipitation since New Year’s Day has now increased snowpack in the San Miguel, Dolores, Animas and San Juan river basins to 89 percent of normal.

As for the remainder of winter, the National Weather Service’s U.S. Seasonal Drought Outlook, which is valid from now through April 30, asserts that southwest Colorado falls under the “drought remains but improves” category.

Fowler predicted some of that improvement will occur in the next week.

“We have a pretty robust system moving through this weekend that should bring a decent amount of moisture to the area, though it will be on the warm side and some valleys could get rain instead of snow,” he said. “The San Juans are looking to get 6-12 inches of (snow) accumulation, with the high peaks getting possibly 18 inches.

“Then we have another system coming through Tuesday and Wednesday that should be colder and deliver a decent amount of snow, but it’s too early to predict accumulation amounts. At any rate, an active, wet pattern should remain.”

Fowler characterized the system — which is moving eastward from Southern California to Colorado — as an “atmospheric river event. It essentially means that moisture is funneled from the tropics to our region.”

Because abundant snow fell after the NWS in October predicted El Niño conditions this winter, many locals believed the El Niño was already happening. But that’s not quite true.

“Right now, we’re still considered to be in a ‘neutral’ pattern concerning El Niño,” Fowler said. “Technically, for an El Niño to be declared we need to record not only warm sea temperatures but also an increase in thunderstorms in the eastern Pacific. Those storms haven’t happened, and that’s why meteorologists can’t declare an El Niño right now.”

Fowler did note, however, that the NWS predicts a 90 percent chance of an El Niño forming this winter and a 65 percent chance of it continuing through the spring time frame, which the NWS defines as the beginning of March through the end of May.

“We hope the moisture keeps on coming so we can make a dent in this drought,” Fowler concluded.

The ‘polar vortex’ Here’s what it means. The Washington Post

January 25

Temperatures are forecast to drop well below zero in the Midwest next week— as cold as around minus-30. The only phenomenon frigid enough to generate that kind of chill is the polar vortex, of which you have heard but might not fully understand.

There are not one but two polar vortexes in each hemisphere, North and South. One exists in the lowest layer of the atmosphere, the troposphere, which is where we live and where the weather happens. The other exists in the second-lowest, called the stratosphere, which is a shroud of thin air that gets warmer at higher altitudes.

If the two polar vortexes line up just right, the Lower 48 can find itself in a very deep freeze.

The low-level vortex in the troposphere is a large mass of brutally cold air and swirling winds coiled around omnipresent polar low pressure. The year-round cold temperature causes air to condense and shrink in size, which creates a vacuum effect that draws air inward.

Polar vortex in the low levels


What is the polar vortex? This graphic pertains to the tropospheric polar vortex.

The tropospheric polar vortex is the one that affects our weather. Most of the time, its harsh conditions are out of reach. But every so often, lobes of it pinch off from the main flow and crash south. This can lash the Lower 48 with piercing shots of cold, intense bouts of storminess and bitter wind chills well below zero. How cold it gets in the Lower 48 depends on how much of the vortex breaks off and how far south it gets.

It is as if the tropospheric polar vortex is a backyard full of dogs, and the jet stream is a fence. The dogs are always trying to escape through gaps in the fence. Occasionally a few of them manage to get out and cause a few days of very cold weather. But once in a while, the entire fence collapses and almost all of the dogs run wild. That is when the big cold-air outbreaks happen.


(weatherbell.com)

Polar vortex up high

The stratospheric polar vortex lives above and separate from the troposphere. It is much more compact than its tropospheric cousin. It forms in a similar way but is smoother and maintains a much sharper edge. That is because there is very little mixing with the air below it. With lots of rotational energy, this counterclockwise gyre can speed with little to slow it down.

The stratospheric polar vortex does not stick around year-long: It disintegrates around March and starts to regenerate again in September; that is when the sun sets on the North Pole for the last time until spring. By December and January, the stratospheric polar vortex is a full-fledged machine. But a strong polar vortex does not mean storms for us. In fact, it is the contrary.


(From Waugh et al., American Meteorological Society, 2017)

Most of the time, the stratospheric polar vortex has little impact on our weather. The two layers of the atmosphere remain largely disconnected.

Once in a while, the stratospheric vortex gets disrupted — a sudden stratospheric warming event. When this happens, the vortex can split and affect the weather below it. It can cause kinks in the jet stream so that, instead of flowing west to east, there are a lot of dips and ridges. And the waves in the jet stream can disrupt the lower (tropospheric) polar vortex, break off a lobe and force it south.

 

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