Avalanche Advisory for Tuesday 1-31-2012

Expires 12:00 midnight, 1-31-2012

All forecasted areas of Tuckerman Ravine have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when warranted.

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

It’s the last day of January and I can’t make up my mind whether to celebrate January or curse it. Compared to December 2011, it was a great month for snow. But on the other hand, far too many days went well above freezing, the most recent being just last Friday, the 27th. Looking at the current weather, the month will end with some accumulating snow. February will open on a sour note, with the weather turning warm once more. It’s currently looking like rain may once again land in avalanche terrain tomorrow. But for now, we’ve just started to receive snowfall that will add to the stability issues that have been keeping us on our toes for the last few days. About an inch of new snow is on the ground and we’re expecting another 3-4” (7.5-10cm) before the day is over. This snow will come with winds on the lighter side for up here. They will be from the west in the 30-45mph (48-72kph) range, which is an excellent speed for allowing loading to take place in the upper elevations of avalanche terrain. As warm air slowly takes over, snow densities will be increasing. Additionally, winds are forecasted to increase in speeds slightly during the day and into the overnight. Together these two factors will make for an upside-down effect in the new slabs. This means we’ll have lighter, weaker snow buried beneath heavier, denser snow. It’s a classic recipe for avalanche activity, so today’s a good day to play it very conservatively with your travel plans.

Yesterday afternoon the skies cleared briefly enough for us to get a good look into both ravines. The loading that occurred in Tuckerman was impressive. Our estimate is that 2-3 feet of deposition took place in strong lee areas such as the Lip and Center Bowl. Not only is new snow problematic here, but the underlying layers have numerous potential weaknesses within the complexity of layering. The exposed crust that dominates Left Gully may have some trouble holding new snow, but in the strong lee of the upper gully there is a likelihood for slabs to develop under today’s conditions. In many locations, anchors have been slowly getting buried, making their effects less important to overall stability. The upper sections of Sluice and Right Gully are good examples. In Huntington, the areas we rated Moderate today have much less developed bed surfaces than all other gullies. It is still possible that you might find unstable areas of snow in North, Damnation, and Yale. The snowfields in the other gullies have all grown in size in recent days and will have the largest potential sliding surfaces for avalanches caused by the new snow.

Above all else, keep in mind that the avalanche danger is increasing as the day goes on. In many areas we’re starting the day with a Considerable rating, and now additional loading is taking place. Don’t let the powder fever allow you to let your guard down.

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 8:15am. 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

2012-01-31 Print Friendly

Avalanche Advisory for Monday 1-30-2012

Expires 12:00 midnight, 1-30-2012

Tuckerman Ravine has Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. The only exception to this is Right Gully which has Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when warranted.

Huntington Ravine has Considerable, Moderate, and Low avalanche danger. Central, Pinnacle, Odell, and South Gullies have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Yale Gully has Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. North, Damnation, and the Escape Hatch have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

The past few days have been rather interesting from a forecasting perspective. Since Friday’s warm rain event, the mountain has seen roughly 6” (15cm) of new snowfall, mostly falling intermittently with breaks of nicer weather in between. From midnight Saturday through this morning, about 2” (5cm) of light density snow has fallen on the summit and at Hermit Lake. While the general trend today is for snow shutting down and visibility clearing, winds will have little difficulty moving the recent snowfall from upper elevations into the ravines. This new loading will continue through today since wind speeds will be on the rise. Today’s Considerable rating is based largely on the potential for naturally triggered avalanches in many areas. Early in the day, poor visibility will limit your ability to make visual assessments of where loading is taking place. You can reasonably assume most aspects in both ravines are receiving some loading. Those aspects facing due E, such as the Lip, Center Bowl, Central Gully, and Pinnacle Gully, are going to be getting the direct load, but we have no reason to believe cross loading will not be taking place in most other areas. As always seems to be the case, expect a high degree of spatial variability as you move from one location to another.

One factor going into our decision making today is the prior development of snowfields in certain areas. In a “normal winter,” Right Gully would probably have been rated Considerable today instead of Moderate. However, the snowfields at the top start zone are really just filling in. There are still sufficient trees to act as anchors in a lot of this terrain. If you venture into larger snowfields within this gully, your chances of seeing stability issues will increase. Similarly, North Damnation, and the Escape Hatch are rated Low primarily because of the lack of snow in the upper avalanche start zones. You may find locations within these forecast areas where windblown snow has collected, and you should assess these carefully or avoid them altogether.

Clearing skies today will hopefully provide mountain travelers the ability to see where they’re going, and use visual clues to help make better informed route choices. Keep in mind that blue skies do not equate to stable snow, especially when additional windloading is taking place above you.

The Sherburne Ski Trail is doing quite well right now. The breakable crust from Friday night has been broken by the weekend traffic. It’s now most similar to packed powder with a handful of icy spots near the bottom. This should continue to improve with additional snow today and tomorrow.

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 8:30am. 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

2012-01-30 Print Friendly

Avalanche Advisory for Sunday 1-29-2012

Expires 12:00 midnight, 1-29-2012

Tuckerman Ravine has Considerable and Moderate avalanche danger. The Lip and Center Bowl have Considerable 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 Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when warranted.

Huntington Ravine has Moderate and Low avalanche danger. Central, Pinnacle, Odell, and South gullies have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. North, Damnation, Yale, and the Escape Hatch have Low avalanche danger. Natural avalanches and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

After a great field day Saturday with lots of interesting observations, Mt. Washington pulled an ace out of its sleeve last night and once again left me recalibrating to a new set of information. About an inch (2+cm) of new light density snow fell on the mountain overnight and W winds have been blowing snow above treeline since 3pm yesterday. Winds have been ideal for loading this new snow into soft slabs in protected lee areas, i.e. they were from the west at 60-80mph (97-129kph) since midnight. The total amount of snow may be small, but with winds like these and light density snow I can’t rule out the possibility for natural avalanche activity today. The areas of greatest concern in Tuckerman are the Lip and Center Bowl. In other areas I expect new soft slabs to be developing throughout the ongoing wind loading situation. While the chances for natural avalanches to occur in these Moderate-rated areas are less than in the Lip and Bowl, the potential for a person to be the trigger puts them into the Moderate realm. Right, Left, and Hillman’s will offer the most stable route-finding options, but care should be taken when traveling in newly deposited slabs. Potential bed surfaces included crust developed after Friday’s warm weather and smooth windslabs that were built in many lee areas by another small snowfall around 9-10pm Friday. Tuckerman has a highly variable snowpack with some interesting layering taking place. It wouldn’t be a big surprise for a small avalanche to step down into deeper layers, the consequences of this happening to a person would be severe.

Huntington has similar issues today with new snow building into fresh slabs, but it has a slightly different bed surface history. Whereas in Tuckerman the lee areas were protected enough to build a foot or more of windslab on top of the wet layer, Huntington was more scoured down. For this reason, the primary concern in Huntington is the new snow deposition from last night and through today. You can find the deepest areas of this at the tops of the approaches to the ice, particularly in Central and Pinnacle. Below Harvard Bulge and Yale slabs is another area to watch out for. There are also newly loaded pockets in some of the upper sections of the gullies you might want to avoid. When possible, stay on the older snow to avoid this issue.

The Lion Head Winter Route is now open. This is a steep route; an ice axe and crampons are highly recommended for safe travel. Please avoid the summer Lion Head Trail due to avalanche risk.

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 8:50am. 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

2012-01-29 Print Friendly

Avalanche Advisory for Saturday 1-28-2012

Expires 12:00 midnight, 1-28-2012

Tuckerman Ravine has Moderate and Low avalanche danger. Right Gully, the Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Left Gully and Hillman’s Highway have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when warranted.

All forecast areas of Huntington Ravine have Low avalanche danger. Natural avalanches and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

One of the first lessons an avalanche student learns is that hazard evaluation is a constant process. One needs to be continually open to new information and questioning every assumption. Coming up the trail from Pinkham this morning, small amounts of new snow drifting into protected areas of the trail caused me to question my own expectations for the day. After temperatures yesterday climbed above freezing at all elevations for several hours, including many hours of freezing rain and rain, I expected a crust to be the prevailing surface in the lower elevations. So where did the new snow come from? One suspected source is the wind. Last night, west winds ramped up to the 100mph+ mark for several hours. This likely ripped up the crust that formed above treeline and exposed the colder, drier, underlying snow from Thursday night to the strong winds. The other source, the one I wasn’t expecting, was new snowfall last night. For a couple hours, just prior to the winds maxing out, there was light snowfall at the summit with totals of about an inch in their collection can. This is what I believe is the source of the drifting down low, and is contributing to stability concerns for today.

In Huntington, as well as the areas in Tuckerman that are rated Low, the new snow will have had a difficult time holding onto the slopes during the sustained strong winds. While most of the surfaces will be scoured down to an older crust, you may find pockets of unstable snow in strong lee areas within the Low rating today. The other areas of Tuckerman have a Moderate rating today based on their ability to hold windloaded snow even during strong wind events. Clouds have prevented me from seeing it firsthand today, but I suspect there will be a mix of conditions in these forecast areas. Some places where wind was able to get at it more, you’ll find relatively stable snow. But in locations that are more protected, the new snow mixing with bits of old snow picked up by last night’s wind, you may find slabs with sufficient elastic energy to propagate a fracture. The Lip and Center Bowl stand out as the most protected locations, but smaller areas such as the mouth of Right Gully and above the narrows of the Chute are also well protected. Beneath any new slabs you’ll find a variety of crust layers, giving a handful of potential bed surfaces. To add more complexity to the forecast today, snow is currently being blown around above treeline. This should subside soon as wind speeds decrease, but remember that if active loading continues it will increase the avalanche hazard.

The Lion Head Winter Route is now open. This is a steep route; an ice axe and crampons are highly recommended for safe travel. Please avoid the summer Lion Head Trail due to avalanche risk.

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 8:25am. 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

2012-01-28 Print friendly

Avalanche Advisory for Friday 1-27-2012

This advisory expires at midnight Friday 1-27-2012

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 and travel in avalanche terrain is not recommended. This includes runout paths of avalanche activity such as the fan in Huntington and the floor of Tuckerman Ravine. The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when conditions warrant.

As expected, we are in the middle of a winter weather maker with about 6” (15cm) on the ground as of 7am. Light snow began just after dark last night and continued through the evening.  Icing has been mixing with new snow beginning to increase densities causing an inverted snowpack giving us stability concerns.  Additionally, loading has occurred from a southerly direction in the 35-45mph (50-72kph)  range over the past 12 hours, this will start shifting and come from the West and increase.  By late in the day wind speeds should be gusting over 60 mph (100kph) from a westerly direction.  Our main concerns through the morning are focused on aspects that have a northern component due to the overnight loading from the South.  As winds shift and increase they will have a larger pickup zone, namely Bigelow Lawn and the Alpine garden, to load the Ravines directly due to their overall Eastern facing direction.  Some cross loading will occur later today on South facing aspects, but locations like the Right Gully in Tuckerman and Damnation and North Gully in Huntington will hit the High rating later than other forecast areas.  Complicating and accelerating today’s instability issues is the transition from snow to….yup…rain.  The summit is expecting a high of about 30F at 6288 and the Conway valley areas are expecting 40-41F early in the afternoon.  There is a good chance we will see rain develop in our primary avalanche terrain between 4000 and 5200ft.  As precipitation moves from snow, to sleet, to freezing rain, to rain it will add load and stress to the new snow and slabs already on the landscape.  When rain begins you should expect a rapid rise in instability and the likelihood of naturally triggered avalanches.  Rain adds load, melts bonds that were contributing to slab strength, and can percolate down to a buried crust, lens, or blue water ice and lubricate this potential bed surface. 

All of these new issues today are falling on a 1” (2.5cm) crust with recrystalized facets underneath.  This now buried crust varies in strength around the ravines depending on whether or not Monday’s rain event was falling on cold slabs or old surfaces.  This factor determines whether you break right through the crust or stay on top.  The porosity of these old layers had a bearing on facet growth and the current strengths and weaknesses we are dealing.  This leads ultimately to my point that a great deal of spatial variability exists across the mountain.  In some locations today new loading from the south may collapse areas with deep facets under the crust and may not in others.  More probable will be the potential that avalanches in today’s new snow and rain may step down and rip out some locations of this crust.  Although today’s new precipitation is by far the main issue triggering the High danger rating this buried problem is one more factor to consider.

Tonight winds will rage, gusting far in excess of 100mph (160 kph).  This should be able to overwhelm any new encapsulation that occur today to move a variety of crystal types and ice pellets down into avalanche terrain causing new problems for tomorrow.  We’ll have to see exactly how this event plays out today to better assess this subject.   Check back for our Weekend Update later today.

The Lion Head Winter Route is now open. This is a steep route; an ice axe and crampons are highly recommended for safe travel. Please avoid the summer Lion Head Trail due to avalanche risk. The Sherburne Ski Trail should be a reasonable choice this morning but expect it to get heavier and turn into some challenging mash potato-glop later.  Buried obstacles still exist although they are becoming less of an issue.

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 8:10am. 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

2012-01-27 Print Friendly

Avalanche Advisory for Thursday 1-26-2012

This advisory expires at midnight Thursday 1-26-2012

Tuckerman and Huntington Ravines have Low avalanche danger today. Natural and human triggered avalanches are unlikely except in isolated features. The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when warranted.  Recognize avalanche activity may occur within these areas before forecasts begin.

Conditions haven’t changed too much from 24 hours ago as clear overnight conditions and just a little snow have left the mountain looking pretty much like yesterday.  Over the past 2 nights we have gone through a bit of diurnal recrystalization in our snowpack underneath the surface crust.  Basically a strong temperature gradient in the snow from the rain event, dropping air temperature, and clear skies allowing for good radiation wave movement has “dried out” the snow under the porous crust.  Grabbing this snow quickly it initially feels like dry powder.  Under further examination it’s actually faceted crystals that morphed from the wet rounds they were 2 days ago.  I mention all this because it means that the surface crust likely will not increase in strength, it may possibly get weaker making for difficult off trail movement without floatation.  Snowshoes or skis will make life easier is most places.  Use caution descending steep terrain and be ready for sudden posthole plunges through the crust.  Snow stability-wise we have widespread Low danger with avalanches being unlikely, watch for some very small pockets (what Joe likes to call “pocket lint”) of new snow from yesterday in a few places. 

As I mentioned yesterday ice climbers should anticipate the problem of “ice dams” which usually occur after a mid-winter rain or thaw.  Freezing temperatures begin creating new ice at choke points which puts water flow under increasing pressure looking for a way out.  Often this way out is your ice tool or crampon hole which can unleash an eruption of ice and water.  This phenomenon has blown numerous ice climbers off their stance over the years.  This hazard generally dissipates with time but can be persistent in isolated areas for many days and is unrecognizable beneath the surface.

The big news is another pre-weekend storm is upon us tonight and tomorrow.  5-8” (12.5-20cm) is forecasted for the mountains, but warm air will infiltrate during the event making precipitation more dense and heavier.  Icing and sleet is almost assured in the surrounding valleys possibility making it to the rain form.  We may be spared from some of this pain, but an inverted snowpack with heavy on lighter snow is probable.  Anticipate an increasing avalanche trend late tonight and into daylight tomorrow and cross your fingers for quiet snow on the landscape and not like some kid hucking gravel on a metal roof.   

 The Lion Head Winter Route is now open. This is a steep route; an ice axe and crampons are highly recommended for safe travel. Please avoid the summer Lion Head Trail due to avalanche risk. The Sherburne Ski Trail had decent coverage, but nothing erodes snow faster than a rainy and foggy night. I expect it will be quite icy by the end of the day with numerous exposed rocks.  

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. January 26, 2012. 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

1-26-2012 Print Friendly

Avalanche Advisory for Wednesday 1-25-2012

This advisory expires at midnight Wednesday 1-25-2012.

Tuckerman and Huntington Ravines have LOW avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when warranted.  Recognize avalanche activity may occur within these areas before forecasts begin.

Snowpack lockup is underway as the concrete cures with the dropping temperatures.  All elevations climbed way above freezing yesterday with the exception of the summit which flirted with the 32-33F (0C) mark.  The melt water from warm conditions, in addition to copious amounts of rain, have deeply penetrated our snowpack making isothermal conditions up until the overnight when the mercury fell sharply.  The current “lockup” is occurring from the surface down as liquid free water in the snowpack freezes creating a thickening crust, which in turn is increasing the snowpack strength.  The crust will vary in strength, but expect breakable surface conditions off packed trails and very hard slick conditions on pack surfaces.  As strength increases, angled terrain will get very slick and hard which will make crampons and an ice ax worth their weight in gold!  Skillful use of these tools will be critical in the case of a slip, trip, or fall to keep you from achieving Mach 1 down steep slopes.  The drag co-efficient between ice crusts and modern Gore-Tex isn’t much so be ready to arrest a stumble very quickly with your mountaineering axe.  Use caution descending steep terrain and be ready for sudden deep post hole plunges through the crust.  Ice climbers should anticipate the growing problem of “ice dams” which usually occur after a mid-winter rain or thaw.  Freezing temperatures begin creating new ice at choke points which puts water flow under increasing pressure looking for a way out.  Often this way out is an ice tool or crampon hole which can unleash an eruption of ice and water.  This phenomenon has blown numerous ice climbers off their stance over the years.  This hazard generally dissipates with time but can be persistent in isolated areas for many days and is unrecognizable beneath the surface. 

As the reset button has been hit we have little concern of any old snow instability that was on the ground prior to the rain event due to the “ bridging” effect of the increasing crust thickness.  However a slight attention should be paid to the upslope snow showers that are expected today forecasted to bring us about an inch (2.5cm).  As the mountain moves through today some very isolated instabilities may develop in lee pockets of W and NW winds gusting over 80mph.  As new loading occurs from some new snow today realize is will be loading on top of slick cold crusts which should make for weak bonds at their interface.  

The Lion Head Winter Route is now open. This is a steep route; an ice axe and crampons are highly recommended for safe travel. Please avoid the summer Lion Head Trail due to avalanche risk. The Sherburne Ski Trail will be challenging as it freezes up tight today.  Expect lots of deep frozen ruts and other frozen pleasures to negotiate.  Check your speed frequently and assure your boards have a fresh tune up for edging needs.

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 8:10am. 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

1-25-2012 Print Friendly

Avalanche Advisory for Tuesday 1-24-2012

This advisory expires at midnight Tuesday 1-24-2012.

Tuckerman and Huntington Ravines have Low avalanche danger today. Natural avalanches and human triggered avalanches are unlikely. The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when warranted; however, you should be aware that avalanche activity may occur within these areas before forecasts begin.

As if this winter hasn’t made us suffer enough, last night the White Mountains region enduring a drenching January rain event. Mt. Washington’s summit received about 0.5” (13mm) of melted precipitation, mostly in the form of freezing rain and rain, while down at Hermit Lake about 0.75” (19mm) of precipitation fell. About the only good thing I can say about this event is that it mostly happened at night. Some of the Hermit Lake precipitation was snow during the daylight hours, but the bulk of the event was rain overnight. As of this morning temperatures have begun to fall. Currently the freezing line is just above the ravines, but as the day progresses this will drop, locking up the mountain in an icy crust.

The end result of this weather pattern will be a very stable snowpack. However, early birds and go-getters should realize that we are at the tail end of a natural avalanche cycle, with a rating of High less than 12 hours ago. As the lockdown takes place the trend is undoubtedly toward stability, but there will be a window of time before everything is absolutely stable. There is currently a lot of moisture in the snowpack. This has had a reasonable amount of time to percolate downward through drainage channels it created within the snowpack. The chances that some of this free water may still reach a cold, dry, weak layer and trigger an avalanche are slim, but they do exist. Similarly, a person may penetrate deeply enough into some sloppy wet snow and hit a weak layer. The best window for this taking place is right now, while ravine temperatures are above freezing or shortly thereafter. On the whole, I don’t believe either of these scenarios presents enough likelihood to warrant more than a Low rating, especially considering the trend toward better stability as the day continues. But remember that Low avalanche danger does not mean the same as no avalanche danger or that there is nothing at all you need to pay attention to. If you want to avoid this potential, just wait a few extra hours for the temperatures to continue to drop.

It seems as though we go through a period like this every winter. One thing that sticks out in my mind after the midwinter thaw is how slick and slippery the steep slopes can become. If you’re planning to be here over the next few days, bring your ice axe and crampons. You’ll need to know how to use them proficiently as well. With the thin snow cover, numerous hazards remain exposed, making a sliding fall a very unwelcome proposition. There’s also a chance for a small amount of snow to fall before tomorrow, which may create stability concerns if it loads onto a smooth ice crust. Stay tuned for more on that tomorrow.

 The Lion Head Winter Route is now open. This is a steep route; an ice axe and crampons are highly recommended for safe travel. Please avoid the summer Lion Head Trail due to avalanche risk. The Sherburne Ski Trail had decent coverage, but nothing erodes snow faster than a rainy and foggy night. I expect it will be quite icy by the end of the day with numerous exposed rocks.

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 8:25am. 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

2012-01-24 Print Friendly

Avalanche Advisory for Monday 1-23-2012

This advisory expires at midnight Monday 1-23-2012.

All forecasted areas of Tuckerman Ravine will have HIGH avalanche danger today.  Natural avalanches are likely and human triggered avalanches are very likely. Travel in avalanche terrain is not recommended.  The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when warranted; however, you should be aware that avalanche activity may occur within these areas before forecasts begin.

Huntington Ravine will have HIGH and CONSIDERABLE avalanche danger. Yale, Central, Pinnacle, Odell, and South Gullies have High avalanche danger. Natural avalanches are likely and human triggered avalanches are very likely. Travel in avalanche terrain is not recommended. North, Damnation, and the Escape Hatch have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely.

New England winters, how do I love thee? Let me count the ways. I love thee for the sleet, the freezing rain, and the rain… My apologies to poetry fans for the sarcastic paraphrasing, and I apologize to winter enthusiasts for what’s to come later today. The primary concern causing today’s High rating is the incoming precipitation expected to begin after dark. A lovely wintry mix is on its way. It’s a familiar pattern with warm air aloft bringing in precipitation while valley temperatures stay cold a while longer. This event is forecasted to bring about a third of an inch (8mm) of water equivalent in the form of snow, sleet, freezing rain, and rain. Most of this will fall during the evening hours and overnight, which will be the time when peak instabilities are reached.

The mix of precipitation types later today will fall onto some very weak snow layers. Westerly winds deposited these over the weekend after a very light density snowfall on Thursday night and Friday. Soft slabs have developed in the protected lee areas, particularly those with an easterly aspect such as the Sluice, Lip, Center Bowl, and Chute. This weak snow will not take well to sleet and rain landing on it late today, so I expect numerous smaller avalanches to occur in a wide range of locations. Prior to any precip, you can expect conditions similar to yesterday. I would be watchful for unstable slabs that a person might trigger, but naturally triggered avalanche activity won’t be a problem until later. There are a variety of surfaces out there on which to travel. If possible, staying on older surfaces and away from newly deposited soft slab will help you avoid trouble. Most importantly today, do everything you can to get out of avalanche terrain before the precipitation begins.

 The Lion Head Winter Route is now open. This is a steep route; an ice axe and crampons are highly recommended for safe travel. Please avoid the summer Lion Head Trail due to avalanche risk. The Sherburne Ski Trail has decent coverage. Be cautious for some buried landmines and waterbars as they still are problem particularly when you can’t see them.  

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 8:45am. 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

2012-01-23 Print Friendly

Avalanche Advisory for Sunday 1-22-2012

This advisory expires at Midnight Sunday 1-22-2012

Tuckerman Ravine has MODERATE and CONSIDERABLE avalanche danger.  The Lip, Center Bowl, and Chute have Considerable avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely.  Dangerous avalanche conditions exist.  Careful snowpack evaluation, cautious route finding and conservative decision making is essential. Right Gully, the Sluice, Left Gully, and Hillman’s Highway have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible.  The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when conditions warrant.

Huntington Ravine has MODERATE and CONSIDERABLE avalanche danger.  Central gully, Pinnacle, Odell, and South Gully have Considerable avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely.  Dangerous avalanche conditions exist.  Careful snowpack evaluation, cautious route finding and conservative decision making is essential.  North, Damnation, Yale, and the Escape Hatch have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible. 

Once again we were teetering on the fence between forecast ratings again today.  Based on the atypical low snow density storm event from Thursday and Friday we have decided to hang on to the Considerable rating for a number of locations that were in the direct lee of West winds.  These winds were the dominate direction for the majority of the loading over the past 72 hours.  Areas that dropped a rating from Considerable you might call “Scary Moderate”. There is a fine line between human triggers being “very possible” (upper end of Moderate) and “likely” (Considerable).  Therefore, recognize that although areas posted at Moderate have more snow stability than the higher rated Considerable locations, many do not linger far behind.  If you decide to go into Moderate posted locales today do not fall asleep at the wheel and give the snowpack a good assessment.  The big factor for all this is the soft slabs that developed over loose unconsolidated low density snow Thursday though Saturday associated with very cold temperatures.  Cold air in place over the region has done little to consolidate or stabilize slabs so the upper snowpack has been sitting in homeostasis.  They have changed very little over the past 2 or 3 days and are waiting for enough time or a slight weather change to stabilize. The other element that could make a change in the snowpack, I.e. fracture and failure, is YOU.  I would be very cautious venturing into soft slabs and choose your routes carefully.  You will find instabilities and slabs vulnerable to human triggers without looking to hard particularly on East facing slopes in the strong lee.  Don’t let the blue bird day suck you into the uncontrollable desire for powder.  Be objective with your analysis and don’t convince yourself everything is fine if you don’t have the data to say that. 

I haven’t said anything about natural avalanche activity potential because it is not too much of a concern.  Dying winds, lack of loading and a slight warm up towards 20F shouldn’t be enough to cause natural slope failures.   But, that will be a different story tomorrow as we move into……. ah yes good ole New England Wintry Mix, aka “mountain slop”, and eventually….rain.  What will freezing rain and rain do to cold soft slabs that have been sitting between -5 and zero degree temperatures you ask?  AVALANCHE!  So the return of natural avalanches issues will likely be the case Monday and Tuesday.  The bright side is this could hit the reset button wiping out instabilities and bridging others making them moot.  More on all that tomorrow.   

We have switched the Lion Head ascent from the Summer Lion Head trail to the Winter route.  The summer trail is not recommended due to the snowfield traverses near treeline and their associated avalanche risk.  Follow the orange signs marking the route at the bottom off the Tuckerman Ravine trail and at treeline where it rejoins the summer trail above the Summer trail avalanche problems.   

 The Sherburne Ski Trail has decent coverage. Be cautious for some buried landmines and waterbars as they still are problem particularly when you can’t see them.    

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 8:45am. 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

2012-01-22 Print Friendly