Avalanche Advisory for Saturday, 3-17-2012

This advisory expires at midnight, Saturday, 3-17-2012

All forecast areas of Tuckerman and Huntington Ravines have Low avalanche danger. Natural and human triggered avalanches are unlikely.

In the ten years or so I’ve been working in the White Mountains, one thing I’ve learned is that every winter is unique in some way. This season is no exception. Not only was every month this winter marked by low snowfall amounts, but the springtime meltout has arrived with force. The past week we’ve already lost dramatic amounts of snow, and we’re just about to begin an intense March heat wave. While today won’t break records, expect to see new high temperature marks set tomorrow and later in the week. Snow stability remains good in the ravines today, though you will probably see some sluffing of wet, mushy snow. Currently the “Big Three” springtime hazards are what you need to be aware of while traveling in either Tuckerman or Huntington this weekend.

  1. Falling Ice. Whether it’s Tuckerman or Huntington doesn’t matter. There is a full winter’s worth of ice melting out of the steep cliffs and gullies, waiting to crash to the floor of the ravines. Through the years, there have been many significant injuries and even fatalities from falling ice. The best way to protect yourself is to avoid spending time in the potential path of icefall, which can happen almost anywhere at this time of the year. In Tuckerman, the most dangerous ice can be found in the Center Bowl as well as directly above Lunch Rocks in the Sluice. If ice falls from the Sluice, you will have nowhere to hide as shrapnel flies all around you. For this reason, Lunch Rocks is not a safe place to sit! You’re better off parking yourself down low in the floor or on the climber’s left side of the Bowl.
  2. Undermined Snow. Currently, this hazard looms largest for those who want to exit the bowl via the Little Headwall. The Little Headwall itself has already collapsed and is an open waterfall. The streambed above is a series of open water holes and weak snow bridges. I strongly recommend taking off your skis and hiking the trail back to Hermit Lake.
  3. Crevasses. This hazard forms as the wintertime snowpack creeps slowly downhill, pulling away from cliffs, rocks, and in places, from itself. These are just beginning to open up, but over the next few days I think we’ll start to see them become more and more problematic. We recommend hiking up the route you plan to descend so you can assess the hazards in advance.

General coverage in Tuckerman is still pretty good, all things considered. Left Gully, the Chute, and left side of the Center Bowl all have decent top-to-bottom coverage. A couple things are not worth your time, such as Lobster Claw, the top of Right Gully, and the Little Headwall. Personally, I’d be looking for two things in my choice of ski terrain today, both are aimed at avoiding bottomless mush. First I’d look to areas where others have compacted the snow through the season. Next I’d head toward runs that are out of the direct sun. Off-the-beaten-track runs and those in the direct sun may have a lot of snow, but you’ll be riding a Slurpee by the end of the day.  Climbing these runs may be a frustrating experience as you punch through, even in places with an existing bootpack.

The Sherburne Ski Trail has taken some abuse this past week. Bare spots, rocks, and water ice have all made their appearance, and with the upcoming weather they’re only going to get worse.

We have transitioned to the Lion Head Summer Trail. The winter Lion Head route is now closed. Please avoid using this route to avoid damaging the soil on the steep section of trail. The Summer Trail does have a lot of snow on it. Plan for wet snow and postholing over the next several days.

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.  
  • 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

2012-03-17 Print Friendly

Avalanche Advisory for Friday, 3-16-2012

This advisory expires at midnight, Friday, 3-16-2012

 All forecast areas of Tuckerman and Huntington Ravines have Low avalanche danger. Natural and human triggered avalanches are unlikely.

If you’re traveling into the ravines today or during the upcoming heat wave, throw out all your preconceived notions of what March is supposed to look like up here. From the appearances of it, the annual melt-out is a month ahead of schedule, if not more. Expect the full onslaught of springtime hazards:

  1. Falling Ice. Whether it’s Tuckerman or Huntington doesn’t matter. There is a full winter’s worth of ice melting out of the steep cliffs and gullies, waiting to crash to the floor of the ravines. Through the years, there have been many significant injuries and even fatalities from falling ice. The best way to protect yourself is to not spend time in the potential path of icefall, which can happen almost anywhere at this time of the year. In Tuckerman, the most dangerous ice can be found in the Center Bowl as well as directly above Lunch Rocks in the Sluice.
  2. Undermined Snow. Currently, this hazard looms largest for those who want to exit the bowl via the Little Headwall. The Little Headwall itself has already collapsed and is an open waterfall. The streambed above is a series of open water holes and weak snow bridges. If you punch through into the icy water, the term “chest deep” might take on a new meaning for you. I strongly suggest you plan to walk out from the bowl, rather than try to find a way through this area.
  3. Crevasses. This hazard forms as the wintertime snowpack creeps slowly downhill, pulling away from cliffs, rocks, and in places, from itself. These are just beginning to open up, but over the next few days I think we’ll start to see them become more and more problematic. We recommend hiking up the route you plan to descend so you can assess the hazard in advance.

If you have the opportunity to stall for a day, you might want to think about not coming today and coming during the weekend instead. Today’s weather forecast isn’t a pretty one. A warm front will turn rain showers into steadier rain this afternoon. About a tenth to a quarter inch of rain is expected in total. Personally, I’d rather be out in sub-zero temperatures than 40F rain. I find nothing more uncomfortable than being wet in these conditions. With that in mind, be sure to bring a couple extra dry layers and some sort of protective shell for today’s weather. Skip the typical post-ski beverage and bring a thermos of something hot instead. If you’re coming this weekend, bring the sunblock, beach chairs, and umbrellas, because it’s going to be that kind of weather for the foreseeable future. I’m not sure how low temperatures will get down to in the overnights, but let’s hope it dips below freezing each night just to help preserve what precious little snowpack there is. If you’re traveling off the beaten path, expect deep wet snow, difficult postholing, and slow progress.

The Sherburne Ski Trail has taken some abuse this past week. Bare spots, rocks, and water ice have all made their appearance, and with the upcoming weather they’re only going to get worse. We’ll post a Weekend Update later this afternoon with some more detailed prognostications for the next couple days.

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.  
  • 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

2012-03-16 Print Friendly

Avalanche Advisory for Thursday, 3-15-2012

This advisory expires at midnight, Thursday 3-15-2012

All forecast areas of Tuckerman Ravine and Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

I pushed all the melancholy spirits out of me yesterday and I have officially said goodbye to winter.  Until the next late winter storm I am fully embracing the idea that spring is here!  We have picked up a dusting of snow overnight and another shot is on the way overnight and into Friday.  This should come in the form of rain due to a warm front passing through the area.  After that, holy cow, say hello to sun, heat, and record breaking high temperatures!  Beginning Saturday sun will dominate the skies bringing the valley mercury up to the 65-70F degree range.  So, outside of our stable snowpack the main thing to talk about is the onset of Spring hazards. 

The slow emergence of crevasses is slowly going to become an issue over the next week.  They are currently small and just beginning to peak out, but this will change under the fireball in the sky over the next 6 days.  Prepare to watch them grow.  Undermining of snow by brooks, streams, and the heat of rocks and bushes is an increasing concern.  It can make snow bridges collapse under your weight particularly while attempting to ski over known streams like when exiting the Tuckerman floor. The most immediate hazard to you is falling ice this week.  Clear skies and direct solar gain over the weekend will warm rock, melt ice bonds, and begin sending a winter’s worth of ice formations crashing down.  Falling ice has caused significant injuries and fatalities over the years and needs to be taken seriously.  The dominate location for this problem is south facing pitches followed by east slopes like the Tuckerman Headwall.  The entire spring hazard discussion will be ramped up over the next few days as well as tomorrow’s “Weekend Update”, issued in the late afternoon.  The brook leaving the floor and the Little Headwall is pretty close to being done, and likely will be sometime this weekend due to some of the warmest temperatures this season on the way.  It wouldn’t surprise me if everybody will need to walk out of the Ravine within the next several days.  The vast majority of skiers and riders are already walking out and we’ll keep you updated daily on this situation.

   In Huntington Ravine climbers will face conditions more similar to mid or late April.   Anticipate questionable ice protection in the sun, so rock gear will obviously be a better option when the terrain allows.  Undoubtedly there will be cold nights and days ahead so timing is everything.   Skiing conditions on the Sherburne Ski Trail should be a little firm to begin the day but should change to softer conditions as the fog burns off and the sun’s heat penetrates frozen surfaces.  You will encounter a number of bare patches down low.  I would expect the trail to change considerably by the end of the weekend.

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 8:40a.m. A new advisory will be issued tomorrow.
 

Christopher Joosen, Snow Ranger     
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856
www.mountwashingtonavalanchecenter.org

2012-03-15 Print Version

 

Avalanche Advisory for Wednesday, 3-14-2012

This advisory expires at midnight, Wednesday 3-14-2012

All forecast areas of Tuckerman Ravine and Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

If we were face to face and I was explaining the overall conditions on the mountain to you it wouldn’t be a pretty sight.  My eyes would be red and weepy, tears rolling off my sunken cheeks soaking my water logged shirt.  My head would be hunched down dreaming of winters gone by, I think you’ve got the picture.  By and large I have a good attitude and am generally optimistic, but until I get over how the mountain is doing it’s hard to candy coat the situation.  Overall there is plenty of terrain to ski and ride, we are just 4-6 weeks ahead (or behind depending on your perspective) of schedule is all. Today is my Monday and oh what a change a couple of warm days can make since I last saw the Ravines on Sunday.  The snow continues to settle, revealing holes, more ice and the initial inklings of several crevasses.  The snowpack is generally stable, but percolation rates moving down to deep buried crusts, linger in the back of my head.  This is particularly true with around the clock above freezing conditions.  However, precipitation has been scant and brooks are still trickling at an average rate so free water in the snowpack has not been substantial.  Today should not be excessively warm with the chance of some light precipitation and clouds.  This will be followed by some freezing conditions tonight with avalanche terrain getting into the twenties F.   The drop in mercury will slow down the prolonged melting rate, contributing to a more conducive tempo of the spring snowpack to keep it in place.   A slower draining pace for melting free water allows impermeable crusts to deal fairly well with, and not be overwhelmed by, heavy amounts of water lubricating the layer’s interface.  Several more days of our spring weather with some precipitation in the forecast should have us fully transitioned to a stable spring snowpack.  After all this spring weather talk, the flip side is a couple of forecasted inches of snow tonight may give us some isolated pockets of new snow to talk about tomorrow.

As we have been discussing in the advisory of late spring hazards are here.  In Huntington Ravine climbers should expect conditions more similar to mid or late April.  Expect all the late spring hazards such as falling ice, rock, and undermining.  Anticipate questionable ice protection in the sun, so rock gear will obviously be a better option when the terrain allows.  Undoubtedly there will be cold nights and days ahead so timing is everything.   As in Huntington, Tuckerman is seeing the same problems. We are witnessing some falling ice, undermining, weakening snow bridges, and open holes in brooks.  The brook leaving the floor and the Little Headwall is pretty close to being done, and likely will be sometime this weekend due to some of the warmest temperatures yet this season on the way.  It wouldn’t surprise me if everybody will need to walk out of the Ravine in the next 2-5 days.  Skiing conditions on the Sherburne Ski Trail should be fairly enjoyable up high and a bit wet and slushy down low with bare patches popping out.  I would expect the trail to change considerably by the end of the weekend.

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 8:05a.m. A new advisory will be issued tomorrow.
 

Christopher Joosen, Snow Ranger      
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856
www.mountwashingtonavalanchecenter.org

2012-03-14 Print Version

 

Avalanche Advisory for Tuesday, 3-13-2012

This advisory expires at midnight, March 13, 2012

Tuckerman and Huntington Ravines have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

For the last couple days we’ve seen warm temperatures, sunny skies, and loads of skiers and snowboarders out enjoying the weather. The snowpack has been generally stable, with any concerns being limited to surface layer snow catching people in small slabs or sluffs. For the most part, the potential for this problem has been mitigated by skiers, boarders, and climbers cutting up the surface snow. Through this process there were a couple of small slabs released, but nothing major. It was incredibly warm yesterday, starting the day above freezing at Hermit Lake. Around noon yesterday, temperatures at the summit had climbed above freezing and they’ve stayed there since then. This all sets the stage for where your avalanche attention should be focused today.

The slopes today will be subjected to even more warm temperatures, along with some scattered showers or drizzle. There isn’t a lot of moisture in the air, so I don’t think you need to be worried about a heavy soaking rain, but it will be foggy and wet. The snowpack will continue to saturate until temperatures drop back below freezing, which will hopefully happen this evening. I don’t think we’re at a point yet where we need to be thinking about deep wet slab avalanches or a devastating blowout of the waterfall hole, but there is one avalanche scenario to point out. Isolated areas of slab sitting in steeper terrain may be prone to avalanching as they become more saturated. Slopes not yet cut up or tracked out are the most suspect. If this happens, the slide will be small and isolated, but it’ll also be wet and heavy. You’re most likely to see this in out-of-the-way areas such as off in the steep slopes to the left of Left Gully or under the Boott Spur Ridge. In Huntington you may find these kind of issues if you’re trying to descend Escape Hatch or in South Gully. Also think about your sluff management today. Imagine skiing in wet concrete or quicksand on a 45 degree slope and you’ll understand why you should be thinking about this.

We had our first report of spontaneous icefall yesterday, coming from North Gully. That isn’t terribly surprising given the sun and warmth. As much as I hate to admit it, we’re at a point in the season where you should be thinking more about icefall. The Center Bowl has one large column that could do some serious damage if it fell out. Huntington, as you might expect, has a tremendous amount of ice that will eventually all fall down. Today may not be sunny, but the warm rain will continue the melting process.

The Little Headwall has begun its annual deterioration. This winter it never really became a quality exit from the Bowl, so even though it’s still officially winter, it’s time to start thinking about walking out of the Bowl. There are open water holes in the stream above, and in the Little Headwall itself. Snow bridges have only recently developed and will be weakened by the recent weather, and water levels will be up, so be cautious if you choose this route. The Sherburne Ski Trail desperately trying to hold its lower section together. Overall conditions will be soft and slushy with some bare spots.

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.  
  • 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

2012-03-13 Print Friendly

Avalanche Advisory for Monday, 3-12-2012

This advisory expires at midnight, Monday, 3-12-2012

 All forecast areas of Tuckerman Ravine and Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

If this past weekend was marked by the arrival of spring, perhaps today could mark the arrival of summer? Not really, but my guess is that we’ll see at least a couple people hike up here in shorts and t-shirts today. Near-record high temperatures are in the forecast, with the ravine elevations of Mt. Washington already well above freezing and only getting warmer. Add to that some full sunshine, relatively calm winds, and a giant bowl-shaped reflector, and you’ve got some classic Tucks conditions. Bring your sunscreen, saxophone, wide-brimmed hat, or whatever makes you happy. If I were you, I’d bring my fattest sliding implements because it’s going to get pretty mushy by the end of the day, especially on S-facing aspects like Right Gully and the Sluice.

Overall snow stability around the ravines will be good today. The concern you’re most likely to face is loose wet sluffs on S and E aspects, i.e. those that get the most sun during the day. Elsewhere, there may be small pockets of slab on steep slopes that’s baking in the sun and haven’t yet seen traffic. These may release, but given their number, size, and isolated nature I don’t believe it’s enough to warrant more than a Low rating. Neither of these are to be taken lightly, as they can easily sweep you off your feet and carry you a long way downhill. Yesterday I alluded to potentially unstable slabs due to prolonged warming. The consensus among us is that it’s unlikely that today’s weather will be sufficient to overcome the stability created by the freezing-up following Thursday’s warm spell and rain. On that day, the summit was above freezing for about 14 hours and at the end of this period a shot of rain came through. This was the first warmth and water to impact the snowpack, but it didn’t trigger any avalanche activity. It quickly refroze on Friday, creating a strong crust layer that should be able to withstand today’s warm up before the threat of naturally triggered wet slabs arises again. The best we can hope for at this time are some cold nights, with temperatures below freezing, to start us on a good corn cycle. If we never go below freezing, we may start worrying again about natural wet avalanches. Let’s hope we don’t go there.

In Huntington Ravine, there is still ample ice in most of the gullies. However, there are some that are lacking a bit for this time of the year, notably the most northern gullies, North and Damnation. Expect the tops of these gullies to be a mix of ice, snow, rock, and turf. During the first hot days such as today, we often see numerous small rockfall events in Huntington, and occasionally some large ones. If you’re climbing in the sun, be very alert to what’s above you, whether it’s falling rocks, ice, or wet sluffs. Any and all of these can be expected today.

The Little Headwall has begun its annual deterioration. This winter it never really became an easy exit from the Bowl, so even though it’s only mid-March, it’s time to start thinking about walking out of the Bowl. There are open water holes in the stream above, and in the Little Headwall itself, so be cautious. The Sherburne Ski Trail is still holding up, but expect melting conditions down low.

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.  
  • 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

2012-03-12 Print Friendly

Avalanche Advisory for Sunday, 3-11-2012

This advisory expires at midnight, Sunday 3-11-2012

All forecast areas of Tuckerman Ravine and Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

All doubts can now be laid aside; spring has arrived. How do I know this? Every year around mid-March, a certain migratory species makes its presence known in Tuckerman Ravine. Stabilitus testorium, known to avalanche forecasters around the world as “volunteer stability testers”, are occasionally found in the eastern ravines during the height of winter. They become prevalent each spring, particularly on weekends. Yesterday a large flock descended on Tuckerman, testing slopes in numerous locations including the Center Bowl and Lip. While the biped variants had little success in their search for instabilities, one four-legged creature managed to release a couple minor propagating slabs while searching for a descent route through the Lip. Mostly though, the initial harbingers of spring were left to contend with sluff management on top of the dominant crust layer.

A quick recap of the weather over the last few days will explain a lot. Thursday night, warm temperatures prevailed with rain reaching all the way to the summit. Following this the mountain has received 3.4” (8.5cm) of new snow along with temperatures falling back below freezing. Some of this snow, about 2”, fell during very strong winds already and isn’t a big player in any stability concerns today. The last 1” or so fell yesterday morning with decreasing wind speeds and is where your avalanche eyes should be focused today. It is within this new snow where the small slabs were released and sluffs were created. There are isolated terrain features that have been able to hold onto pockets of new snow. Based on what was seen yesterday, there is a reasonably good chance these pockets are unstable. In addition to what was there yesterday, increasing wind speeds today have already begun to move some of this new snow around, obscuring and reloading some of the tracks laid down by yesterday’s ski traffic.

In the big picture, these areas of new slab on top of the crust are rather small. While they may not be large enough to deeply bury a person, they can certainly knock you off your feet. If that’s not bad enough, if you are standing in the runout admiring your tracks while one is kicked off by someone else, you’d better get out of the way in a hurry. Better yet, just don’t stand in the runout admiring your tracks. Move away to a safe area and enjoy the view without risking a severe and humiliating thrashing at the hands of a seemingly small slide.

Looking ahead to tomorrow, temperatures at the summit are projected to reach above freezing. If overnight lows don’t get below freezing, then we’ll have a prolonged period of warm temperatures, which may increase instability. The first warm days of the season can often be “heads up” kind of days. If you are thinking about a day in the ravine tomorrow, be sure to read the morning advisory.

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.  
  • 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

2012-03-11 Print Friendly

Avalanche Advisory for Saturday, 3-10-2012

This advisory expires at midnight, Saturday 3-10-2012

Tuckerman Ravine has Moderate and Low avalanche danger. The Lower Snowfields and the Little Headwall have Low avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features. All other forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.  

Huntington Ravine has Moderate avalanche danger.   Natural avalanches are unlikely and human triggered avalanches are possible.  Evaluate snow and terrain carefully and identify features of concern.

Extreme wind dominated the early part of yesterday on the higher summits.  Mount Washington hit 114mph (185kph) from the NW before rapidly subsiding through the day.  Certainly these early velocities did their job to scour many locations, with the exception of strong lee areas.  Clouds still envelope the hills, playing with us, occasionally giving a glimpse of what occurred overnight.  Staying at the ready with binoculars allowed some clues to jump out, helping us ascertain what issues are held in Tuckerman this morning.  As of this writing Huntington is still enshrouded in fog and clouds.  After the high winds decreased in speed on Friday, snowfall continued and added up to about another inch (2.5cm), while down at the 3800ft level between 1 and 2” (2.5-5cm) fell.  The final inch was very light in density at 4%, allowing low wind speeds to load snow into avalanche terrain.  In total, over the past 32 hours the summit picked up 3.1” (7.5cm) while Hermit Lake hit a bit over 4” (10cm).  Based on how winds played out during this period I would expect quite variable conditions, from scouring on exposed slopes with a dusting of new snow, to some unstable slabs in our stronger lee terrain of W and NW winds.  Generally you will find the full range within the definition of “Moderate” from the lower end near, but not quite in “Low”; and a solid Moderate particularly under the Tuckerman Headwall ice over through the Sluice to the north.  This steep area is very well protected even from extreme western winds.  The experienced and avalanche skilled traveler, doing constant evaluation of stability and route choices, should find some reasonable options.  In Huntington, we believe more scouring and wind ripping of the terrain occurred.  But due to clouds we can’t confirm whether or not we have only isolated pockets of concern, a definition component of a Low rating, or slightly greater snowfields more in line with a Moderate rating.  Because many of the gullies are so narrow the difference in snowfield sizes may only be several meters between ratings.  Very often pockets of instability that can be easily avoided may deserve a Low forecast, while a choked gully with no options but to plod through new slabs or descend may receive a Moderate rating.  We are currently in this delicate scenario forcing us to a”Moderate” choice due to hampered visibility.

Winds are expected to slowly increase in speed from the current of 20mph (32kph) to 50+ mph (80kph) tonight.  The low density snow that fell yesterday during winds between 10 and 40mph (16-64kph) will begin to be loaded at some point in the velocity transition.  Therefore, watch for snow loading activity later in the day and be ready to deal with an increasing danger by altering plans if needed.   All weather data indicates this shouldn’t happen until after dark, but a slight wind speed forecast error could make the difference for loading today so keep your eyes open.  Although clouds should keep heating at bay, watch for solar gain potential on southern aspects if long periods of direct sun coincide with today’s low winds. This may increase the possibility of sluffing and a very remote chance of a slab failure.  In general, I think it will be a nice winter day to be above treeline due to light winds and reasonable temperatures climbing close to 10 degrees F (-12C).      

      Off trail travel will still be tough without floatation so skis or snowshoes are recommended.  Open water holes are still present in the brook when leaving the floor of the Ravine, use caution when traveling through this area.  The open holes on the Little Headwall are increasing in size and may not be visible from above.

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 8:50a.m. A new advisory will be issued tomorrow.
 

Christopher Joosen, Snow Ranger     
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856
www.mountwashingtonavalanchecenter.org

2012-03-10 Print Version

 

Avalanche Advisory for Friday, 3-09-2012

This advisory expires at midnight Friday, 3-09-2012

Tuckerman Ravine has Considerable and Moderate avalanche danger. The Sluice, Lip, and Center Bowl have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely.  All other forecast areas have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible. The only exception to this is the  Little Headwall which has Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine has Moderate avalanche danger.   Natural avalanches are unlikely and human triggered avalanches are possible.  Evaluate snow and terrain carefully and identify features of concern.

Winter decided to go on sabbatical over the last couple of days to learn a few things about being harsh, allowing its nemesis, Summer, to take over the region.  The Mount Washington Valley climbed into the mid sixties F yesterday, while avalanche terrain said hello to about 50F with the onset of rain in the early evening.  Well, Winter’s thoughtful time away made him anxious to get back so he came raging back in like a freight train overnight hitting 120mph at 7pm.  Temperatures dropped from 36F at 11pm to 4F this morning, enabling the transition from rain to snow.  The summit recorded 0.3” of rain that fell from 6 to 11pm before snow began, giving us 2.1” as of 6am this morning.  Down here at Hermit Lake we have received +/-3” since the rainfall yesterday.  The precipitation type that changed over last night has allowed for good initial adhesion at the interface between new snow and the old wet surface.  As new slabs develop in the strong lee, such as under the Tuckerman Headwall ice, Lip, and Sluice, failure would occur above this interface in new snow.  Areas blown clear by high winds the surface are now cold and slick, although textured with lots of nooks and crannies.  New snow bonding in these locations won’t be as good due to cold icy surfaces, but that should start to occur late today as wind speeds plummet.  The other factor to consider is how the new, growing snowfields are insulating the warm 0C snow underneath at varying levels.  This will add to the spatial variability in regards to facet growth rates and bonding of new snow making for a shambolic situation. 

Today’s avalanche ratings are all due to new snow, not the old, warm snow which will continue to lock up with dropping temperatures.  The bulls-eye points today are reasonably straight forward.  First, between 2 and 3” (5-7.5cm) of new snow has fallen and it’s still snowing at a half an inch (1cm) an hour intensity rate (S-1).  Second, loading winds from the WNW at 67 gusting to 83mph is moving snow from the alpine zones down into both Ravines. And third, as wind diminish through the day new snow will load into lee terrain more readily lowering the scouring rate, particularly in Huntington Ravine.   These factors create concern for the possibility of natural avalanches in several lee areas in Tuckerman, forcing the Considerable rating for the Sluice, Lip, and Center Bowl.  Locations adjacent to these 3 forecast areas, namely Right Gully, Left Gully and particularly the Chute should be bumping against the ceiling of the Moderate rating.  In Huntington, where all forecast areas have Moderate avalanche danger, we have the most concern about Central, Pinnacle, and Odell. They also may be knocking on the Considerable door, as snow loads below the lower ice, near the approaches experience frequent sluffing and spindrift activity.  Due to the very high winds overnight you will undoubtedly find scoured sections down low in both Ravines as well as narrow locales where wind vortexs are higher.  Realize you may be on old surface during approaches but that may change once on route.  Low visibility for a good portion of the day will hamper quality route assessment.     

Off trail travel will still be tough without floatation so skis or snowshoes are recommended.  Open water holes are still present in the brook when leaving the floor of the Ravine, use caution when traveling through this area.  Check out “Weekend Update” later today for additional information for the next couple of days and be sure to read Saturday morning’s avalanche advisory before heading up to the Ravines.

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 8:50a.m. A new advisory will be issued tomorrow.
 

Christopher Joosen, Snow Ranger   
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856
www.mountwashingtonavalanchecenter.org

2012-03-09 Print Version

 

Avalanche Advisory for Thursday, 3-08-2012

This advisory expires at Midnight, 3-08-2012

Tuckerman Ravine has Considerable, Moderate and Low avalanche danger. The Sluice, Lip, Center Bowl, and Chute have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Left Gully, Hillman’s Highway and the Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Lobsterclaw, Right Gully and the Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine has Moderate and Low avalanche danger. Central, Pinnacle, Odell, South, and the Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

One thing this heat wave has going for it is we haven’t had the usual rain associated with it, which always adds to the overall enjoyment of a good thaw.  This will change a bit later today due to the 50% chance of rain for the afternoon, but it shouldn’t be enough to dramatically affect avalanche danger.  Although the rain should be a part of your overall stability equation, the intense warming and sluffing over the past 30 hours has helped cook out slab propagation potential near the surface. (Read on for deep instability concerns). Therefore, the current snowpack should handle the light rain amounts expected, forecasted to be somewhere around a tenth of an inch.  These light amounts shouldn’t have substantial percolation rates down into the snowpack before precipitation turns to snow and we see the mercury drop like a rock with the approaching cold front.  As the temperature falls below freezing in avalanche terrain liquid water that exists within the snowpack will begin freezing from the surface down stabilizing all forecast areas.

Before the overnight temperatures begin locking up the existing snowpack we do have a lingering concern about warming getting deeper in the snowpack affecting one of multiple weak layers, that have been moot until now.  We have ice crusts and lens at varying depths that change from locale to locale; and buried ice bulge to ice bulge.  I get lightheaded thinking about the intense slope scale spatial variability in regards to crust depths we have scattered around the Ravines that may be impacted today by the continued warming trend.  Hermit Lake is currently at 45F degrees and sunny.  I would expect most of our avalanche terrain to be about the same, looking at the Mount Washington Observatory’s Auto Road Vertical Profile.  Some significant surface point release sluffing occurred late yesterday in Hillman’s Highway and the Duchess, and to a lesser degree in the Tuckerman Bowl, due to the daytime heating.  As we progress further into our thaw I can’t ignore the nagging feeling and remote concern of a deep slab release.  I do feel this potential is slim but it must be recognized as we go through our first substantial warm up in a long time.  The areas posted at Considerable hold my highest attention with naturals being possible.  Locations posted at Moderate take a backseat with naturals being “unlikely” but not entirely out of the question.  The Lobsterclaw and Right Gully were skied heavily yesterday with deep ski penetration and compaction.  Their gully nature, ski traffic, and limited size has me much less worried about deep instabilities allowing the Low rating today.  I would expect more slow moving sluffs today which could entrain you, causing real problems depending on your run out.  As yesterday, very high winds will continue to dampen the effects of the warm air temperatures on the snowpack.   Currently winds are blowing at about 70mph, but are anticipated to be over 100mph today and even higher overnight with the intruding cold front.  Their cooling affect has definitely helped limit widespread heat penetration, softening the avalanche danger potential.

Off trail will be brutal without floatation so ski’s or snowshoes are a must.  Some undermining on the brushy ski out of Tuckerman should be expected.  Open water holes are still present in the brook when leaving the floor of the Ravine, use caution when traveling through this area.  Tonight slopes will stabilize, but our new concern may turn to fresh snow issues in the morning.  Additionally the avalanche aficionado may want to watch for the development of near surface faceting as we expect ambient air temperatures around -15C with a surface snowpack at 0C.  So, we are hitting the reset button and in the end if we make it through today with out much avalanche action we will be in a better place by the weekend.     

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 8:50a.m. A new advisory will be issued tomorrow.
 

Christopher Joosen, Snow Ranger     
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856
www.mountwashingtonavalanchecenter.org

2012-03-08 Print Version

Avalanche Advisory for Wednesday, 3-07-2012

This Advisory expires at midnight, Wednesday 3-07-2012

Tuckerman Ravine has Considerable and Moderate avalanche danger. The Lobsterclaw, Right Gully, Sluice, Lip, Center Bowl, Chute, and Left Gully have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Hillman’s Highway and the Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Little Headwall has Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine has Moderate and Low avalanche danger. Central, Pinnacle, Odell, South, and the Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

Today is a full on avalanche brain teaser with a number of factors for the avalanche enthusiast to consider.  Three dominant issues and their exact timing are the important parameters that have generated today’s avalanche forecast.  Since the weekend, the upper mountain picked up about 7” of very low density snow with low to moderate wind speeds ever since.  Yesterday’s peak wind of 65 from the NW did a fairly respectable job pushing around most of this alpine snow, but today winds are expected to ramp up, possibly hitting the century mark this afternoon.  This will augment the current snow plumes already at the ridge potentially causing some new loading concerns.  While this occurs, continued warm air will be escorted by the high winds causing the first substantial warmup for the cold snowpack in a while.  Although we did see a little bit of solar gain yesterday, today’s warm up will be more significant.  There is a strong likelihood for avalanche terrain to remain above freezing overnight before increasing in temperature even more on Thursday with a chance of rain.  The summit is expecting the mercury to be in the mid thirties F today, while here at Hermit Lake it is currently just shy of 40 degrees already.  There will be a battle between increasing temperatures and wind speeds today.  As winds continue to pick up they will help keep many snow slopes cool even as the ambient air gets warmer.  So the exact timing of each of these and how they affect one another is the key factor to observe today.  A number of strong lee areas from W winds, with a SE and S aspect component, will warm the most today in the direct sunlight.  I have an nagging concern about these areas and the potential natural slope failure as the tensile strength of cold slabs get baked out over some under riding facets and unconsolidated snow weaknesses below. 

So we have both some new cold slab issues due to loading snow with increasing winds and then some intense warming mostly on protected southern aspects.   Ultimately I believe there is a good chance new snow loading, high winds, and increasing wind issues will balance each other out coming to a reasonable equilibrium.  However, I cannot ignore that these factors may escalate enough to possibly cause a natural avalanche hence the “Considerable” avalanche danger rating for a number of our largest snowfields and particularly those facing S.  In Huntington these S faces are posted at “Low” due to their overall thin ribbon like nature and how high W winds rip these narrow gullies more readily than in Tuckerman.  This should keep the majority of S faces cool enough to limit the concern.  

Tomorrow, slopes may still be above freezing at dawn with the chance of rain.  This may continue to escalate the avalanche danger so be prepared for continued natural avalanche problems with a higher magnitude than today.

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 8:40a.m. A new advisory will be issued tomorrow.
 

Christopher Joosen, Snow Ranger     
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856
www.mountwashingtonavalanchecenter.org

2012-03-07 Print Version

 

Avalanche Advisory for Tuesday, 3-6-2012

This advisory expires at midnight, Tuesday 3-6-2012.

Tuckerman Ravine has Considerable and Moderate avalanche danger. The Sluice, Lip, Center Bowl, Chute, and Left Gully have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. The Lobster Claw, Right Gully, Hillman’s Highway, and Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely; human triggered avalanches are possible. The Little Headwall has Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine has Moderate and Low avalanche danger. Central and Pinnacle gullies have Moderate avalanche danger. Natural avalanches are unlikely; human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

It’s pretty amazing what a small amount of moisture in the atmosphere can accomplish. Two nights ago, an unexpected upslope snow event took place, laying down about 7” of very light density snow across the higher terrain. This has since been subjected to W to NW winds blowing 35-50+mph (56-80kph), which has moved a lot of snow into Tuckerman Ravine. Across the upper rim of the ravine, the winds have scoured away the new snow, pushing it into stronger lee areas such as below the Lip, below the ice in the Center Bowl, and above the narrows of Left Gully. Other locations have also accumulated a significant amount of snow; the areas mentioned are just some of the most notable ones. This morning, skies are clear and temperatures cold. The NW 50mph (80kph) winds are currently at the upper end of what they were forecasted to be, and due to the winds there is a consistent ground blizzard bringing additional snow into Tuckerman. Today’s Considerable ratings are in large part due to the threat of naturally-triggered avalanches, but we are also thinking about how it would be likely for a person to trigger an avalanche in these newly developed slabs. In addition to the most recent snow, field work over the weekend gave us some concerns about underlying stability in the 12” snowfall from last Thursday. Recent weather has been preventing that dry, light snow from stabilizing in many areas.

Huntington Ravine was affected differently by the new snow. The northern gullies (North, Damnation, and Yale) were mostly scoured down. This is unusual with wind speeds being on the lighter side, but with such light density snow, it is not unreasonable. Central and Pinnacle were obscured by constant plumes of blowing snow. We suspect less scouring took place here than the northern gullies, but the airborne snow prevented us from confirming this. Odell, South, and Escape each have some localized areas of concern, but these are small enough to be considered “isolated terrain features.” If you pay attention in there, you can stick to areas with old surface or a thin veneer of new snow on top of the old surface. However, in the isolated areas you may find unstable new slabs that can avalanche underfoot as well as hard wind slabs that are thin enough to crack and avalanche.

Solar energy today might be a double-edged sword. One the one hand, it can help snow become more stable, if the energy it provides is strong yet gentle. On the other hand, if it’s too strong and not gentle enough, the stability trend can quickly stop and the snow can rapidly become unstable. Southerly-facing slopes will receive the most solar gain, while E and N facing slopes won’t be affected much. The next couple days are looking pretty warm, with temperatures heading above freezing all the way to the summit. Our field work today will be focused on how this might impact stability in the next couple days.

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.  
  • 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

2012-03-06 Print Friendly

Avalanche Advisory for Monday, 3-5-2012

This advisory expires at midnight, Monday 3-5-2012.

All forecast areas of Tuckerman and Huntington Ravines have Considerable avalanche danger today. Natural avalanches are possible; human triggered avalanches are likely. The only exception to this rating is the Little Headwall, which has Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

I guess it’s true what they say about weather being unpredictable at times on Mt. Washington. In the most recent instance, it worked in favor of those who want more snow, but against those who were looking to recreate in avalanche terrain today. Over the last 30 hours, the summit has recorded 6.5” (16.5cm) of new snow. Yes, that’s correct, six and one-half inches. Not only is the total depth remarkable and unexpected, but the density is incredibly light, coming in around 2%. If we hadn’t seen these flakes with our own eyes, we wouldn’t believe the accuracy of the measurement. But they were practically floating in the air like little helium balloons, so I’m a believer. Most of this snow fell between noon and midnight; winds during this time started very light and increased to their current speeds of around 40mph (65kph) from the WNW. A small amount of additional snow is expected to fall this morning.

Today’s stability concerns are primarily related to the new light density snow. It doesn’t require a strong wind to move this snow from one location to another (e.g. from the Alpine Garden into Central Gully). New soft slabs are being created and are growing as I type this advisory. Despite the trend for skies clearing today with high pressure, winds will continue to pick up and deposit the recent snow into steep slopes of both ravines, even after skies clear later today. Direct loading and cross-loading will be taking place in all forecast areas. Expect new slabs to be soft and very reactive to triggering, either from a person or from the increasing load of wind-transported snow. I want to emphasize that today’s Considerable rating is for both human triggered avalanches being likely as well as the possibility of natural avalanches.

The threat of avalanches today is real, and presents additional concerns. We are also thinking about the chances of an avalanche stepping down into slabs that existed prior to the new snow. Field work yesterday showed a spatially-variable snowpack, with some locations registering some frighteningly easy test results while other areas showed reasonably good stability at the surface. We can foresee an avalanche that does step down into older instabilities being quite large, and that conclusion was drawn even before we knew there would be another 6.5+” of snow about to be loaded onto the slopes. Overall, this is a complex snowpack that will require focused attention to navigate safely. To conclude, I recommend avoiding avalanche terrain until visibility improves, and then you’ll need to give some serious consideration to your objectives for the day. There are always options that don’t involve avalanche terrain.

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 8:35a.m. 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

2012-03-05 Print Friendly

Avalanche Advisory for Sunday, 3-4-2012

This advisory expires at midnight, Saturday 3-03-2012. 

All forecast areas of Tuckerman Ravine have Considerable avalanche danger today. Natural avalanches are possible; human triggered avalanches are likely. Two exceptions to this rating: the Lower Snowfields have Moderate avalanche danger, natural avalanches are unlikely and human triggered avalanches are possible, and the Little Headwall, which has Low avalanche danger.

Huntington Ravine has Considerable and Moderate avalanche danger today. Central, Pinnacle, Odell, and South Gullies have Considerable danger. Natural avalanches are possible and human triggered avalanches are likely. North, Damnation, Yale, and the Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanche are possible.

We’ve got a fairly complex set of variables to wrestle with this morning, including recent weather history, avalanche activity, and forecasted weather, so bear with me as I do my best to distill these down into something useful. What we’re dealing with for snow stability is the aftermath of Thursday’s heavy snowstorm. In case you missed it, we received over a foot of light density snow while winds were out of the SE and E. Winds have since shifted back and forth from the W to the S and are currently from the W again. Summit wind speeds last night got very strong, gusting to 99mph (160kph), but we are suspicious that the strongest winds stayed aloft and did not push very far below the summit. The lack of wind-scouring in places such as Hillman’s is an important clue toward this suspicion. In Huntington the upper reaches of the gullies received some scouring, but the middle and lower sections were more loaded than we’d expect after this weather pattern. Meanwhile yesterday, the mountain warmed up and some freezing drizzle created a thin crust everywhere except underneath tree cover. Although it received some freezing rain or drizzle, the uppermost elevations of Mt. Washington did stay below freezing. The avalanche activity we can observe this morning is also less than we would have expected with yesterdays weather, and it’s difficult to determine when exactly these took place. I’m confident enough to say that numerous avalanches have happened in several areas since Friday night, when winds started to pick up.

So starting out today, we’ve got numerous forecast areas that are preloaded with fresh new slab. Based on recent activity, it’s a safe assumption to say these newly developed slabs have some existing instability problems. Currently, many places are in the upper end of the Moderate rating, such as midsections of Odell and South in Huntington and the Sluice, Lip, and Hillman’s in Tuckerman. Today’s weather forecast calls for a chance of additional snow, though only a trace to 2” (5cm) is expected and most of this will come in the afternoon as a weak cold front passes by. Winds will be from the W and decreasing in velocity, but I would expect the speeds to be sufficient to deposit any new snow onto the already loaded slopes. This will drive the avalanche hazard from the upper end of Moderate solidly into the realm of Considerable. Not only will naturally-triggered avalanches be possible, but the likelihood of a person triggering a slide will be elevated as well. If new snow accumulations don’t materialize, actual avalanche hazard in the Considerable rated locations will continue hover between Moderate and Considerable. If the upslope snow guns start up earlier and heavier than expected, then the trend will be toward increasingly unstable snow.

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 8:45a.m. 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

2012-03-04 Print Friendly

Avalanche Advisory for Saturday, 3-03-2012

This advisory expires at midnight, Saturday 3-03-2012

Tuckerman and Huntington Ravines have HIGH avalanche danger today.  Natural avalanches are likely and human triggered avalanches are very likely.  Very dangerous avalanche conditions exist on a variety of slope aspects and angles.  Travel in avalanche terrain is not recommended, including run-out paths.  The only exception to this is the Little Headwall which has Moderate avalanche danger.

The old adage, “you don’t know where you’re going if you don’t know where you’ve been” is a perfect sentiment to capture our developing avalanche situation today. Let’s back up a couple of days.  On Thursday our most recent storm hit the mountains, dumping about 12” (30cm) on the Presidential Range.  Overall snow densities where light, averaging about 7% with the last 4” (10cm) being around 4%.  During and since that snowfall, winds have been quite light for Mount Washington, averaging about 28-29mph with brief gusts over 45mph on Thursday.  Through most of Friday, summit winds hovered around the 20 mph mark. Down at the horizon of the Ravines, at approximately the 5000ft level, wind speeds were less, leaving our new fluffy blanket fairly unaffected except in the more exposed locations. Then at midnight, several hours ago, snow began falling again with an increasing wind.  By 3:30am, Washington’s summit was averaging about 60mph, gusting to 74mph, from the South.  After relative calm period, I can almost hear it yelling, “hey guy’s I’m back, what’ya been doing?!”  Winds today are forecasted to shift, walking clockwise from the current S towards the W.  As winds shift to our prevailing directing and continue to build speed, our east-facing Ravines will get overwhelmed with the left over storm snow lying in the alpine zone.  This is particularly true in Tuckerman due to Bigelow lawn, a flat plateau the size of 600 football fields.  This area sits above the Ravine right in line for winds with a westerly component, providing an incredible supply of snow to be moved.  I would expect more than one avalanche cycle out of this event as slopes get reloaded, cocked to fire, and the trigger pulled by the final flake and gravity tugging on steep slopes.  The light densities will also make cross loading of S-facing areas easier than usual.  Although these slopes will not harbor the dangers of N and E aspects today they will still likely produce natural avalanches.  In areas such as Damnation and North, avalanche activity may be limited to smaller slabs and sluffs, but these can still easily knock you off a stance. To add to this entire situation, new snow has been falling over the last 4 hours and is expected to continue through the day, perhaps changing forms into a bit of a “precipitation grab bag”.  The summits forecast is for 2-4″ (5-10cm) of snow, sleet, and freezing rain, maybe even followed by rain. As these heavy forms of precip fall, any pre-existing instabilities will rapidly become worse.

All of this history and current weather translates quickly and definitively into today’s rating of “HIGH”.  All of our forecasted slide paths have fully developed tracks so you can expect full avalanche runouts to occur.  Although the light density snow can be easily picked up for transport today, crystals will be pulverized into small grains as winds increase, making for denser slabs packed in the deposition.  This increased mass may push some avalanches full path, criss-crossing the floor and approach fans of both ravines.  Travel in avalanche terrain, which includes run-out paths, is not recommended.  As blowing snow and clouds will offer very limited visibility, going into the Ravines just to look won’t give you much more than placing yourself as lead pin in the bowling alley.

The warmth that is expected today won’t last too long. Probably just long enough to make a mess of the nice snow at lower elevations, such as on the Sherburne Ski Trail where the lower sections are currently getting a freezing rain coating. Overnight, mountain winds will start to crank up, perhaps blowing over 100mph for a short time, then decreasing again into good wind-loading velocities. Tomorrow’s avalanche danger will depend in large part on avalanche activity today, more snowfall overnight and tomorrow, and whether or not the overnight winds were able pummel any gullies into full submission.

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 8:05a.m. A new advisory will be issued tomorrow.

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

2012-03-03 Print Friendly