Weekend Update for Friday, 3-29-2013

The calendar says that it’s spring but it wasn’t corn snow I just skied in Right Gully. Boot top, fluffy and blown in. The goods, certainly by East coast standards. I even made it a point to avoid the two steep drop-ins that sported mid-winter pillows ripe to slide on skiers right  since someone could be below me in the runout.  And apparently, I was right. It was spring skiing in the minds of a posse of 20 or so who somehow thought it was a good idea to boot directly up the runout of Right Gully.  And others in Sluice.  And those 4 hiking straight up the runout of Left.  And the father who made his way up to the narrows of the Chute with his 2 small children.  As an an avid backcountry skier, I love seeing people do their homework, make their field assessments and reach their decisions to rip the tassels off a sweet powder line, but today was a lot to digest as a new Snow Ranger.  And given the forecast for the weekend, the crowd, not one of them wearing a beacon, is just getting warmed up.

But I digress. Looking ahead at the forecast for the weekend I would be thinking about several things if I was looking for a backcountry skiing destination. One, go someplace adventurous with a north east through northwest facing aspect ideally, narrow enough and steep enough to contain a lot of blown in pow. It’s there, I know it, because I skied it on my days off. Lots of mid-elevation gullies are waiting for skilled parties, fearing little in the way of blundering overhead triggers, to sign their names to the snow.

If you have your heart set on skiing and climbing in the Cutler River drainage you will certainly have options.  Today’s solar gain started to work quickly on southerly aspects even though there were only brief spells of clearing.  By and large the snow remained cold and dry in Right Gully and from what I could see elsewhere on the solar aspect.  That could change tomorrow afternoon in lee areas in the middle of Lobster Claw through the Lip where the snow will probably get a bit denser, and possibly more unstable.  There will be a window in the late morning hours where ski conditions will remain really good, and that may be the case all day depending on wind speeds and cloud cover, but be on the look out for existing slabs to possibly weaken through the day if heating ratchets up. Early signs of coming instability will be rollarballs and pinwheels, icefall from the Sluice and just generally wet snow on the surface that wets your glove when you squeeze it.  You’ll know it too when it piles up on top of your boots.  The varying thickness of the slab over our rain crust/bed surface is the nagging concern. The recently loaded snow has covered the 3 foot thick crown line in Center Bowl and Sluice quite deeply in spots.  Where the slab is thick, skiers could pass uneventfully.  Put 30 skiers on the hangfire or below it and there could be trouble even without potential heating of the slab.  Hopefully, things will stay cool and powderhounds can have some more fun.

Climbers venturing into Huntington should enjoy good ice conditions with most snow climbs yielding easily to boots. Steeper, wind scoured areas of old rain crust will be scattered around and will present challenging self arrest conditions, generally near the tops of Damnation, Yale and Central. Those same gullies will harbor the greatest threat of natural rock and icefall as the high sunlight works on melting the ice.  Odell’s will be a mixed bag but should provide fairly secure booting up the upper  part of the climb above the ice.  Conditions will lean further towards postholing as you continue around to South and Escape Hatch. Skiers take note.

Overall this weekend we have in store a pleasant continuation of mild winter conditions even though the calendar, valley temperatures and most peoples schedules say that it is spring.  So, pack your bags and head out while winter is still holding on.  And don’t forget to watch for the other guy above you because he may not be looking out for you.

 

Avalanche Advisory for Friday 3-29-2013

This advisory expires at 12:00 midnight tonight.

All forecast areas of Tuckerman Ravine and Huntington Ravine have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully and identify features of concern. The only exceptions to this rating are the Little Headwall, which have Low avalanche danger. Natural and human triggered avalanches are unlikely in these areas except in isolated pockets.

Another day, another uncertain upslope snow event. That was the focus of our forecaster meeting this morning. Several times this month we’ve seen upslope events drop much more snow than expected, and other times not much materializes. Yesterday we had the latter, with only 0.5” of snow falling on the summit and a dusting around Hermit Lake. Today’s forecast is similar to yesterday’s, with a trace to 2” (0-5cm) in store with NW winds blowing 25-40mph (40-65kph). The range of snow makes for a challenging avalanche forecast and puts more of the burden on you to pay attention to what is actually taking place throughout the day. (Of course, this is no different than what you should always be doing.)

Let’s start with the scenario that would produce the greatest avalanche concerns. Let’s suppose we do get 2” of snow with summit winds blowing at the upper end of the rating, around 40mph with some higher gusts. There have been approximately 3” of snow which has fallen in the past couple days, so we’d be looking at a grand total of about 5” of snow available for loading into lee slopes. That’s a lot of snow to be loaded into slabs in the ravines. Expect these to be pretty soft and weak in the most protected locales, such as the Center Bowl or Central Gully. Most other areas would also develop fresh new slabs under this scenario, whether through direct loading or cross loading, and the problems would most likely be found in the middle to the top of the gullies or slide paths. If it plays out, this worst-case scenario would have some areas pushing the upper limits of the Moderate rating. As one who travels frequently in avalanche terrain, this is the scenario I’d be expecting, that way I’m not disappointed when I decide to turn back due to worsening conditions.

I’ll preface the following scenario with the fact that wind speeds have already exceeded the 40mph mark. In this alternative best-case scenario, suppose winds do become light, around 25mph, and we only receive another trace amount of new snow. This may produce smaller pockets of unstable snow, but would limit the widespread development of slabs. Prior to the upslope snow of the last couple days (i.e. before Wednesday), stability was generally good. Some areas, such as Hillman’s and Left, had very stable snow. Others had mostly very stable snow with smaller areas of concern; Right Gully and Lobster Claw are examples. The center portion of Tuckerman, from the Sluice through Chute, had fairly good stability, but if one were to trigger something here it could be sizeable. In the absence of significant new wind loading from yesterday and into today, we’re left with good underlying stability, but will have concerns for human triggered avalanches in the uppermost slabs. In this situation with little snow and light winds, some areas would have difficulty getting into the Moderate range.

Hopefully you can see the range of possibilities today. Don’t expect to see much of the ravines today, they’re thickly in the fog at this time and we may not have much of a break until tomorrow. Speaking of tomorrow, we’ll be posting a Weekend Update later this afternoon with our thoughts on what’s in store for the coming days. Look for it in The Pit section of our website.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted at 8:30a.m., March 29, 2013. A new advisory will be issued tomorrow.

Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713  TTY (603) 466-2856

2013-03-29 Printable