Thursday, April 27, 2017 at 5:33 AM Issued by: Nick Barlow
Snowfall since Monday, April 24th now exceeds a foot in many areas throughout Colorado, with much more expected beginning Wednesday night. Heavy storm snow and moderate westerly winds will create increasingly dangerous avalanche conditions in the backcountry this week. You can trigger an avalanche in the surface snow on any steep slope with more than about 6 inches of recent storm snow. The most dangerous slopes face north through east to south at higher elevations. In these areas, wind-drifted slabs could be 2 to 3 feet thick.
To reduce your risk, avoid bulbous-looking snow surfaces, cross-loaded terrain features, and overhanging cornices near ridgetops. Red Flags like cracking in the surface snow, collapsing, or signs of recent avalanches are clear indications of dangerous conditions. If you observe these signals, safely move to lower elevation terrain with slope angles less than about 35 degrees. Also, pay attention to lurking danger above you. Conditions can be very different at higher elevations this time of year.
The Southern Mountains saw less snowfall since Monday. Until more storm snow arrives, avalanches may be smaller and less numerous in the backcountry. However, these avalanches could still be dangerous on steep, committing slopes, or near terrain traps. Consider the consequences of even a small avalanche affecting your balance or sweeping you off your feet. Trauma accounts for about one-fourth of avalanche fatalities in North America. Keep this statistic in mind before venturing onto higher elevation slopes with greater exposure.
Cooler temperatures and cloud cover should limit the threat for wet avalanche in the backcountry this week. However, pay attention to steep, rocky slopes if the sun comes out. This week’s storm snow will shed quickly at the first glimpses of sunshine and warming. Make sure you’re in a good spot, clear of steep terrain and avalanche paths before this cycle occurs.
With more than two feet of new snow possible by Saturday, large Wind or Storm Slab avalanches are not out of the question. Keep an eye on the weather in your zone. We’ll update this forecast on Friday 4/28, or earlier as conditions warrant.
We have made impressive strides in our mission of avalanche forecasting and education here in Colorado. Help us continue that trend and donate to the Friends of CAIC fundraising campaign. https://avalanche.state.co.us/donate/
Rain and snow showers will increase in both coverage and intensity Thursday afternoon in advance of a cold front currently tracking through Utah. By noon Thursday, higher elevations of the Park Range and Flat Tops could see more than a foot of new snow. For other areas in the Northern and Central Mountains, I expect 4 to 9 inches of new snow, with localized higher totals. Elsewhere, look for 3 to 5 inches of new snow as far south as the Northern San Juan Mountains. We'll see a brief lull Thursday afternoon/evening, before another strong storm feature takes aim at Colorado.
We will continue to issue morning and afternoon zone weather forecasts until the end of April. You can find our zone weather forecasts here. You can also monitor hourly weather conditions on our weather stations page, as well as point weather forecasts for many mountain locations in Colorado.
AVALANCHE AND SNOWPACK
During spring, our ambitions sometimes push us towards higher elevation peaks and objective-based missions. It’s true snowpack stability can improve this time of year to support these missions. Yet, we still need to assess stability day-by-day on a slope-by-slope basis, just like any other time of the year.
Consider this skier-triggered avalanche last Friday in Rocky Mountain National Park. The avalanche caught and swept three skiers collectively down a steep, rocky couloir, eventually burying them up to their waists. There were no injuries reported, but it was certainly a close call. Incidents like these are good reminders that dangerous avalanches occur every month of the year in Colorado. Rapid swings in avalanche danger are sometimes difficult to measure, especially after extended stretches of enhanced stability. The calendar says late April, but during spring storm cycles like these, avalanche conditions at higher elevations are more indicative of late January. It's important to continue exercising mid-winter caution, conservative backcountry protocol, and safe travel techniques in the mountains.
Observations and field reports are limited this time of year in Colorado. However, several layers of recent storm snow, suspect old/new interfaces, and prime wind speeds at higher elevations are worrisome. Forecaster intuition, experience, and weather station data point to an increasingly-dangerous backcountry environment. This week's late-season snowfall is both a gift and a peril. It's a lot of fun to play in, but it also requires our utmost respect. If you make it out and see anything interesting, please submit an observation.
We will issue statewide avalanche summaries Sunday, Wednesday, and Friday, or as conditions warrant, through the end of May.
|@CAIC: Increasing avy danger statewide due to heavy snowfall! Stay conservative & avoid steep slopes w/ >6" new snow.||Apr 27, 1:36 PM|
|View||Thu Apr 27||-||>TL||SE||SS||AS / u||R1||D1|
|View||Wed Apr 26||-||>TL||E||C||N||-||D1|
|View||Tue Apr 25||-||<TL||NW||L||AS / c||-||D1|
|View||Thu Apr 27||Scott Toepfer||No||Yes (1)||Yes (2)|
|View||Wed Apr 26||Spencer Logan||No||Yes (1)||No|
|View||Wed Apr 26||Brian Lazar||No||No||No|
|View||Wed Apr 26||Jeff Colt||No||No||No|
|View||Wed Apr 26||Steven Miller||No||No||Yes (2)|
|View||Wed Apr 26||Calen Orlowski||No||No||No|
|View||Wed Apr 26||Abel Palmer||No||No||No|
|View||Tue Apr 25||Wil Rickards||No||No||Yes (2)|
|View||Tue Apr 25||Josh Hirshberg||Yes (1)||Yes (1)||No|
|View||Mon Apr 24||wil Rickards||No||No||Yes (3)|
|Station||Date||Time||Temperature||Relative Humidity||Wind Speed||Wind Direction||Max Gust||24 Hr Snow|
|Bear Lake||Thu Apr 27||3:00 PM||34||-||-||-||-||3.0|
|Bottle Peak||Thu Apr 27||4:10 PM||18||97||30||283||40||-|
|Berthoud Pass||Thu Apr 27||4:00 PM||17||88||18||359||29||-|
|Cameron Pass||Thu Apr 27||3:00 PM||27||80||14||242||29||4.2|
|Cottonwood Pass||Thu Apr 27||3:00 PM||17||93||11||288||30||3.1|
|Grand Mesa - Skyway Point||Thu Apr 27||5:00 PM||26||69||3||292||12||4.1|
|Kendall Mt||Thu Apr 27||4:00 PM||15||93||20||239||42||-|
|Loveland Pass||Thu Apr 27||4:00 PM||17||85||16||300||29||-|
|Molas Pass||Thu Apr 27||4:00 PM||31||34||7||250||21||5.5|
|Putney||Thu Apr 27||4:00 PM||17||66||33||300||52||-|
|Swamp Angel||Thu Apr 27||4:00 PM||27||49||5||215||18||6.9|
|Vail Pass - Cdot Yard||Thu Apr 27||4:00 PM||21||97||4||345||17||4.7|
|Wolf Creek Pass||Thu Apr 27||4:00 PM||22||96||26||232||42||-|
|Monarch Pass (050e200)||Thu Apr 27||4:12 PM||23||91||8||-||20||-|
|Independence Pass (082w062)||Thu Apr 27||4:15 PM||-||11||-||5||-||-|
|Columbus Basin||Thu Apr 27||3:00 PM||33||-||-||-||-||8.0|
|Hayden Pass||Thu Apr 27||3:00 PM||35||-||-||-||-||2.0|
|Lizard Head Pass||Thu Apr 27||3:00 PM||39||-||-||-||-||4.0|
|Mc Clure Pass||Thu Apr 27||3:00 PM||38||-||-||-||-||2.0|
|Medano Pass||Thu Apr 27||3:00 PM||43||-||-||-||-||-|
|Mesa Lakes||Thu Apr 27||3:00 PM||31||-||-||-||-||2.0|
|Ripple Creek||Thu Apr 27||3:00 PM||34||-||-||-||-||11.0|
|South Colony||Thu Apr 27||3:00 PM||33||-||-||-||-||5.0|
|Slumgullion||Thu Apr 27||3:00 PM||28||-||-||-||-||6.0|
|Schofield Pass||Thu Apr 27||3:00 PM||28||-||-||-||-||-|
|Storm Peak Observatory||Thu Apr 27||3:35 PM||20||100||18||283||23||-|
|Taylor Park||Thu Apr 27||3:57 PM||33||67||8||349||19||-|
|Wolf Creek Summit||Thu Apr 27||3:00 PM||33||-||-||-||-||5.0|
|Zirkel||Thu Apr 27||3:00 PM||29||-||-||-||-||6.0|