Avalanche Advisory for Thursday, 2-09-2012

Advisory expires at midnight Thursday 2-09-2012

Tuckerman Ravine has both LOW and MODERATE avalanche danger. The Lobster Claw, Right Gully, Left Gully, and Hillman’s Highway have Low avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features. All other forecast areas in Tuckerman have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. 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 LOW avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features.  Expect these pockets to exist and avoid them by staying to more stable older surfaces. 

Another beautiful day is welcomed with open arms, but it does put an end to our snow everyday in the month of February streak.  There is a little bit of active snow loading near the top of Hillman’s Highway, climber’s hard right.  Outside of this the mountain has been devoid of much change for the first time since January.  The cold air has only allowed slow change for slabs deposited on Tuesday so we still have some snow stability concerns.  Skier traffic did some good testing of Right Gully as a hard face-plant is equal to about a one pound hand charge.   This is a dominate factor in its dropping to Low today.  The Chute and the Sluice are a mix of Low and Moderate depending on your location.  In the Sluice, areas to the climber’s right down low under the ice do not harbor as much concern for us as the steeper sections do, as you move past the climber’s left side of the ice.  In the Chute, areas from the narrows down low and up above to the climbers left are less of an issue than up to the right on the shoulder leading to the left edge of the headwall.  Use some caution in these two locales as initially you will be fairly stable snow, but that will change if you start jumping all over these forecast areas, hence the Moderate rating.  The Lip and Headwall have seen some time to stabilize slightly but still warrant our attention, as they have the highest instabilities.  Left gully saw at least a couple folks traveling its entire length witnessed by the boot pack left behind that zigzags through the start zone and up the center to the horizon. 

Over in Huntington generally stable snow conditions exist.  Isolated pockets of concern do exist but they are fairly straight forward to avoid.  The bottom of Central and South Gully are some examples of these isolated terrain features.  Another sunny day tomorrow with moderate temperatures will be the last relaxing day in the sun before the weekend changes come our way.  Some precipitation may come into the region for the week’s end overnight on Friday, Saturday and into the end of the weekend.  Some very cold air moving in on Sunday is also in store; temperatures may go below -20F in the higher mountains into Monday morning.  More on that and the light snow coming in tomorrow’s advisory and Friday evenings “Weekend Update”.   

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

2012-02-09 Print Friendly

Avalanche Advisory for Wednesday 2-08-2012

Expires at midnight Wednesday, 2-08-2012

Tuckerman Ravine has both LOW and MODERATE avalanche danger. The Lobster Claw, Left Gully, and Hillman’s Highway have Low avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features. All other forecast areas in Tuckerman have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. 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 LOW avalanche danger.  Central gully has 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.  Expect these pockets to exist and avoid them by staying to more stable older surfaces. 

Last weekend I mentioned hitting a new benchmark soon as rock cliffs, islands of ice bulges, and brush anchors become buried leading to more frequent avalanche activity.  As these features disappear the bed surfaces become bigger which in turn struggle more to hold on to larger snowfields.  I’m impressed how far we’ve come, particularly in Tuckerman, since February began.  The summit has picked up snow everyday this month adding up to 9.2” (23cm) reinforcing the old discussion that Washington often gives snow to us slowly, but with dramatic results.  Of these 9.2” the summit recorded about 2 unexpected inches (5cm) yesterday showing the mountains are not 100% predictable all the time.  This loaded in through Tuesday and into early this morning on perfect NW and W loading winds from 40-65mph (65-105kph).  This gave much of Tuckerman a nice new blanket of snow most notably in the Lip and the right (north) side of the Center Bowl. Other adjacent areas like the Sluice and the upper Chute weren’t left out, but are a bit behind the previously mention locations. 

Because of our field time yesterday in the Sluice area, loading since then, and the visuals at dawn, I believe we are on the upper end of the Moderate rating bumping against the next rating level, Considerable.  Two main issues are driving this for me today. One being new cold slabs (0 to +5F) reactive to a human trigger being strongly possible; and two, warm solar gain building on some of these slopes that have a southern component due to clear sunny skies and low wind speeds this morning.  Of these the main concern is for human triggers moving through the Lip area and over to the Center Bowl.  However I have a slight lingering concern for enough heat to build in the Sluice and over towards the edge of the Lip area to feel natural potential may be on the cusp of moving from unlikely towards possible.  So,  I believe the best rating to reflect the situation today is Moderate, but understand we are at the ceiling of the rating particularly on the northern half (right) of Tuckerman.  In areas post at Low wind scouring and hard conditions prevail although a few isolated pockets do exist, like in the mid section of Hillman’s, below the “Y” and near the top of the Lobsterclaw.  In Huntington, the gullies didn’t hang on to much snow, but a few exceptions exist.  The bottom half of Central has the most new snow of any forecasted gully, hence the Moderate rating.  Other locations have varying degrees of scouring with a pocket or two here and there, but certainly nothing that isn’t covered in the Low definition.  Although the gullies were stripped of new snow it has been deposited in a number of protected approaches near the top of the “Fan”.  Areas under Yale, the Harvard Bulge, and across the Ravine under South gully are a few examples.  Clear conditions are expected today, tonight, and tomorrow with temperatures between 0 and 15 degrees.  Outside of protected southern aspects I would expect new slab instabilities not to settle much over the next 48 hours.  Another issue to keep in mind that Jeff discussed yesterday and which was supported by field work yesterday is the numerous layers including 5 different crusts from thaws and wet precipitation events.  New avalanche activity would quite plausibly step down to one of these crusts in the upper 6.5 feet (2m) due to the facet growth weaknesses around 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 8:55a.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

2012-02-08 Print Friendly

Avalanche Advisory for Tuesday, 2-7-2012

Expires 12:00 midnight, 2-7-2012

Tuckerman Ravine has both LOW and MODERATE avalanche danger. The Lobster Claw, Right Gully, Left Gully, and Hillman’s Highway have Low avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features. All other forecast areas in Tuckerman have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. 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 LOW avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. Expect these pockets to exist and avoid them by staying to more stable older surfaces. 

Yesterday morning the summit of Mt. Washington received 1.2” of new snow. They must be stockpiling it up there somehow, because very little made it down here to Hermit Lake. At our manual snowplots we only recorded a trace, but strong winds may have blown some off the boards. Although we can’t be sure how much snow actually fell into avalanche terrain yesterday, one thing we can be sure about is that the wind did transport snow into the ravines. A brief clearing window in the mid-afternoon allowed us to see that the tracks in the Sluice and Lip area had been filled in. We were also able to see an underlying older surface beneath the new layer in many areas. Taking it all together, we were given a good idea of the amount loading that took place.

Two snow stability issues stand out for me today. One is yesterday’s snow which created unstable slabs in isolated terrain features within areas forecasted at Low danger. These are most likely to be small in size and isolated from larger slopes or snowfields, however, you should still have your avalanche eyes open when you find yourself in areas of freshly deposited slab. This is particularly true this season, when the consequences of any fall are magnified by the thin snow coverage.

The second concern is found underneath the new surface. A variety of layers and interfaces can be found in the Moderate-rated locations. As usual, the depth and exact characteristics will vary depending on exactly where you are. The thread that ties them all together is the existence of two buried crust layers. The uppermost of these was the most noteworthy, acting as the sliding surface in all of our pits on Sunday. During this time, southerly aspects were receiving a good shot of solar energy, which helped stability of the uppermost snow layers on these slopes. In other areas, the sun wasn’t hitting so strongly, so they didn’t get this effect, such as the Center Bowl and Chute. If you dig deeper down into the snowpack, you’ll find another crust layer. To get this layer to fail would probably take a significant impact force. I don’t foresee a person doing this, but the weight of an avalanche on the surface certainly could. The point in mentioning this is that you should be thinking about more than just the upper layers sliding. The increased consequences that come along with a small avalanche are potentially severe.

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 8:15a.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

2012-02-07 Print friendly

Avalanche Advisory for Monday, 2-6-2012

Expires 12:00 midnight, 2-6-2012

Tuckerman Ravine has both LOW and MODERATE avalanche danger. The Lobster Claw, Right Gully, Left Gully, and Hillman’s Highway have Low avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features. All other forecast areas in Tuckerman have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. 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 LOW avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. Expect these pockets to exist and avoid them by staying to more stable older surfaces. 

I don’t know if it was the game or the long term weather forecast that put Mount Washington in a foul mood this morning, but it’s in a thick, disorienting fog that, every so often, allows a glimpse of underlying irritation and anger. Today the winds will be blowing around the 80-90mph range with stronger gusts later today. Visibility will be poor as well, due to fog and additional snow being transported into the ravines from the other side of the mountain. These conditions will make above-treeline travel challenging. Although some wind loading is expected today, I think there will be insufficient quantities to bump the forecasted danger level above where it was yesterday, so today’s ratings are identical with the exception of Right Gully, which as been dropped to Low danger. This is the result of two factors, one, the distribution of the snowfields in Right being broken up enough that each potential bed surface is isolated and easy enough to mitigate or avoid, and two, the amount of skier and hiker traffic in there yesterday was significant enough to break up any potential surface slabs.

In many areas of Tuckerman and Huntington Ravines, you’ll find very good stability. Left Gully and Hillman’s Highway are examples in Tuckerman where you would have a hard time finding instabilities larger than an isolated pocket. The center of Tuckerman is a different story altogether. In my field assessments yesterday, I found myself thinking, “man, if I were 15 years younger and didn’t know anything about avalanches, these could be the best turns of my life!” Over in the Chute and left side of the Headwall, I was finding a very soft layer of surface snow with a medium-hard slab underneath it. The problem layer was below this slab, as the crust from last Wednesday had been forming a thin layer of early faceted snow on top of it. In numerous stability tests, this is the layer on which the slab failed. The depth and thickness of the layer varied, but in general it existed from the Chute through the Center Bowl. Over in the Right Gully/Sluice area, the faceting wasn’t found. We suspect strong solar radiation on those aspects helped prevent the formation of this layer, but we were still able to get consistent and remarkably easy failures in several snowpit tests. Based on these observations and plentiful visual clues, I’d put the bull’s eye for stability problems right under the ice in the Center Bowl. Working outward from there you will have improving stability, but won’t reach what we’d call Low danger until you get into the Left or Right Gully. Some people did get out and put tracks down in the Sluice and Lip area. Don’t take this as an indication of stability or of the skill and savvy of these people. Whenever you see three people clustered together on a 40 degree windloaded slope with an exposed boulder field for a slide path, it is easy to draw conclusions about the party’s skill level assessing avalanche hazards. Sometimes it’s reasonable to travel on a Moderate-rated slope, but we always recommend only exposing one person at a time to the avalanche hazard.

If you haven’t done so lately, I’d encourage you to browse around on our website and our Facebook page. We’ve slowly been adding features, such as a form for you to submit your own avalanche observations. We’ll be using Facebook as our primary means for giving conditions updates on the Sherburne Trail as well.

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 8:15a.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

2012-02-06 Print Friendly

Avalanche Advisory for Superbowl Sunday 2-5-2012

Tuckerman Ravine has both LOW and MODERATE avalanche danger.  The Lobster Claw, Left Gully, and Hillman’s Highway have Low avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features.  All other forecast areas in Tuckerman have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible.  Heightened avalanche conditions exist on specific terrain features.  Evaluate snow carefully to identify these areas of concern.  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 LOW avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features.  Expect these pockets to exist and avoid them by staying to older more stable surfaces. 

On this clear beautiful morning you’re probably wondering how is he going to tie in the Superbowl with avalanches?  Well funny you should ask because the issues that developed yesterday, and we are dealing with today, are directly related to the ole gridiron.  Yesterday the summit picked up 1.2” (3cm) of new snow and 1.2” (3cm) in the 48 hours before that totaling 2.4” (6cm) over the past 3 days with strong W and NW winds between 40 and 80 mph (65-129kph).  We remark so often that low snow amounts can make such a remarkable difference in snow stability due to impressive new slabs.  Avalanche textbook editors may conclude we’re nuts when we get into all the issues and conversations related to 1-2” of snow, but the issues are real and that’s where football comes in.  Above Tuckerman and Huntington Ravines is a large plateau below the summit cone consisting of Bigelow Lawn and the Alpine Garden.  These large expanses are the initial snow collection fields before our dominate W/NW winds plow it all into the basins below.  Bigelow lawn being about a mile square is equivalent to about 590 football fields (1.1 acres each) side by side not including end zones.  Now picture a row of big bucket loaders plowing 2” off all these fields into the Ravine catch basins below.  You’ve seen a small version of this when you go to Walmart and see the mountains of snow at the far end of the lot after a dusting.  Now you’ve got the concept!

We were impressed yesterday how much the Ravine changed yet again due to the aforementioned concept.  Right Gully, the upper Sluice, The Lip are all good examples of larger growth from this last 3 days of loading.  Some folks found themselves in mid-thigh low density slabs in some lee areas.  Through yesterday and overnight strong wind velocities moved a lot of this low density snow out of the Ravines or down low into protected locations on approaches.  This has left behind widespread wind effect in Hillman’s, Left Gully, and most of Huntington. There are some some sizeable locations of leftover slab, hence the Moderate rating for most of Tuckerman and the concern for isolated pockets of instability in Huntington. Snowfields in Tuckerman’s Center Bowl and Lip are getting bigger as rock and water ice continue to get buried with each snowfall or loading event.  Larger snowfields without anchors and delineators such as cliffs and ice are generally easier to trigger than smaller slopes given the same consistent weak layer.  Although it’s getting rather late into the winter more of our forecast areas are moving towards average, which will in turn begin increasing our concern for more frequent avalanche activity.  But as for today, expect the usual spatial variability on Mount Washington with hard stable surfaces interjected with new snow instabilities in strong lee locations that were protected from wind scouring.  If you’re flexible on where you go today you will have a number of options to remain in stable terrain.  However if you insist on traveling through new soft slabs without constant stability evaluations you may possibly avalanche a slope in “Moderate” forecasted terrain and some isolated pockets in areas at “Low”.  Some light snow showers are expected late in the day along with a lowering cloud deck.  This should not affect today’s stability, but be sure to check tomorrow’s advisory before entering avalanche terrain for any issues that developed overnight.     

  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 8:20am. 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

2012-02-05 Print Friendly

Avalanche Advisory for Saturday, 2-4-2012

This advisory expires at midnight Saturday 2-04-2012

 Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. The Lip and Center Bowl have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. All other forecasted areas of Tuckerman have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Included in the Moderate rating for the first time this season is the Lobster Claw. The Lower Snowfields and Little Headwall remain not posted due to a general lack of snow. Forecasts for these areas will begin when conditions warrant.

All forecast areas of Huntington Ravine have MODERATE avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully.

Another small snowfall should be keeping you on your toes today. While our avalanche forecaster friends in western states might chuckle at the idea that an inch of snow can create bona fide avalanche concerns, that’s the reality of Mt. Washington. Don’t let the amount of snow fool you into complacency. Yesterday the summit began recording light snow at about 3pm. This continued through the overnight, leaving about an inch (3cm) across the mountain by daybreak. Currently, the snowfall rate is around 1cm per hour with brief heavier bouts. How long this continues will play a role in how far up the danger scale we go today. Even if it were to stop snowing completely, 50-70mph (80-113kph) W winds this morning will be able to transport the freshly fallen and readily available snow into the ravines from elsewhere on the mountain. Late in the day winds will decrease into the 35-50mph range, but this should still be able to carry the light density snow (6-7%) into avalanche start zones. The weather trend for later today is for at least partially clearing skies and the diminishing winds already mentioned.

What this is adding up to is a situation in which avalanche danger is creeping upward this morning. In many areas, we expect to reach the upper end of the Moderate rating due to new wind loaded slabs. This rating defines human triggered avalanches as “possible” and naturally triggered avalanches as “unlikely”, but we want you to keep in mind the potential for natural avalanches as you travel around today. Not only is the trend for increasing instability due to ongoing loading, but it is also a Saturday morning with lots of people on the mountain and poor visibility. If you’re hit with an avalanche as you’re walking into the Bowl to “take a look around” or “check it out”, I’d bet you won’t care so much whether it was triggered naturally or by another person trying to find their way through the fog. Knowing the trigger will take second fiddle to wondering if anyone actually saw you get buried and assessing the extent of your injuries. In the areas we believe naturally triggered avalanches are most possible, we have posted a Considerable rating. If new snow continues to fall for longer than forecasted or adds up to more, expect other areas to surpass the Moderate rating and move into Considerable territory. Bear in mind that in order to get to adjacent areas with a Moderate rating, you may be crossing the runouts of these higher rated slide paths.

As you can see, the primary threat today is related to new snow and wind loading that is currently taking place. Second to this concern, there are older instability issues that you should also be aware of. Snow that came on the heels of Wednesday’s warm rain and mixed precip event was being blown about all day yesterday. Much of this was sluffing downhill and piling up onto various terrain features. In some areas it was blown into pockets of reactive, energetic slabs, and some of these were sitting on deep pools of graupel. Overall, this would have been enough to keep a lot of areas at a Moderate rating even if it weren’t currently snowing. Any avalanche activity today might very well step down into deeper layers creating a larger avalanche than you might expect from new snow alone.

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.
 

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

2012-02-04 Print Friendly

Avalanche Advisory Friday 2-03-2012

This advisory expires at Midnight Friday 2-03-2012

Tuckerman Ravine has MODERATE and LOW avalanche danger.  The Right Gully, 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 except in isolated terrain features, which do exist.  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.  Damnation, Yale, Central, Pinnacle, Odell, and the Escape Hatch have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible.  North Gully and South Gully have Low avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features. 

Beautiful clear skies dominate Mount Washington this morning with a stunning alpenglow to top it off.  As micro-scale forecasters, alpenglow is one of the holy grails for confirming some of our assessments when we can get it.  This special pink light brings out tremendous contrast to surface conditions highlighting old from new surfaces, wind effect, old sluff tracks, fracture lines, ski tracks, etc.  It obviously can’t tell much about stability of new snow, but it adds more information and data for our final evaluation.  It helped enormously this morning for dropping some areas to Low from Thursday’s Moderate and gave clarity to why other locations need to stay at Moderate.  New snow that came in following the rain event on Wednesday hasn’t added up to much, but has been enough to create some instabilities.  The summit has reported 3.5” over the past 2-3 days, half of which occurred during periods of icing and mixed conditions when the summit hit a maximum of 30F ( -1C).  The second half was dry cold snow, causing most of the present cold slabs.  This snow has been transported on W and NW winds peaking at 86mph (138kph) 36 hours ago with velocities up and down ever since.  Speeds dropped briefly into the single numbers yesterday and now are back into the 40’s mph range which is causing some light loading in a few locations.  Light afternoon snow showers may continue this loading trend but it shouldn’t make much of difference for today.  We’ll discuss anything that becomes of it in Saturday’s advisory.

In areas that are posted at Moderate in Tuckerman, you will find some old surface and stability in some locales, but enough concern exists about the amount and size of new snow within the forecast area they warrant the Moderate rating.  Right Gully and the Sluice are on the lower end of the Moderate definition.  From the Lip over to the Chute new snow can be found mostly in a band at the Headwall ice elevation and immediately below this feature.  This is acting as our primary new snow concern today.  As you move into Left Gully isolated pockets of instability can be found on the climber’s right side from down low up to the narrows.  The upper climber’s right “Y” exit chute of Hillman’s Highway also harbors some instability.  In both these “Low” areas, this new snow can be avoided by staying to the hard left on your ascent.  

In Huntington, North and South gullies have Low avalanche danger due to either the lack of snow or strong wind effect.  The rest of the Huntington forecast areas have Moderate avalanche danger with little wind effect and some locations picking up a good amount of new loading in strong lee areas such as under steep ice like the Pinnacle approach.  Because of the thin nature of the Yale and Damnation exits 2-3 days ago these noticeably stand out as doing quite well from a seemingly scant amount of new snow. 

We will be getting into the field today to see how areas of cold slab are adhering to the old surface and how facets are doing beneath the rain crust.  We’ll pass along any pertinent info we determine today in the “Weekend Update” early this evening.  Look for it on www.mountwashingtonavalanche center.org.  Post-holing through crust will be a real issue in numerous off trail locations making travel rather arduous.   Ice climbers should also be prepared for ice dams, or water under pressure, beneath the ice from Wednesday’s rain and freeze up afterwards.  An ice tool or crampon placement can release this with explosive results.  Bulges and rollovers are more likely to harbor these hazards than depressions. 

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

2012-02-03 Print friendly

Avalanche Advisory for Thursday 2-2-2012

 

Expires 12:00 midnight

Tuckerman and Huntington Ravines 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.

As anticipated Wednesday turned out to be pretty sloppy, but in true New England style things have changed once again.  After a full morning of rain in avalanche terrain temperatures nosed back down and fell overnight changing precipitation back over to snow.  A few glimmers through the fog this morning gave us some signs of avalanche activity due to yesterday’s rain.  Dodges ran full path to Hillman’s Highway, which also avalanched to the dog leg. Clouds have kept us from seeing much more this morning, but this evidence indicates it’s quite likely other activity has occurred.  Before losing a view yesterday we saw widespread wet point release sluffing in both ravines. Free water from melt and rain has been going through the refreezing process currently making instabilities below Wednesday’s surface moot.  The summit temperature this morning of 11F and Hermit Lake’s 19F is quickly changing sub-surface liquid to a solid state.  There is some evidence these wet rounds are already faceting under the multilayered crust. This change is on going, but the new snow issues from last night and early this morning are what we need to focus on today as the bulls-eye issue.

The summit never fell below freezing but got awful close at 30F (-1C), and subsequently did not get rain. However their 3” of new “snow”, with a water content of 0.63”, appears to have seen a period of mixed precipitation.  This new snow up high was delivered to the Ravines on an increasing W wind peaking at 86mph (138kph) during the overnight.   A thin blanket of snow and small drifts can be found on the trail from Pinkham to Hermit Lake, where about an inch was recorded.  Some new cross-loaded small cornices can be seen high near the climber’s left ridge of the Sluice and the Lobster Claw due to high W winds overnight.  This gives us some good clues about strong lee areas and the probability of new snow deposition.  A quick view of the Sluice before fog returned also showed evidence of new snow through out, in the early morning light.  Expect newly formed cold slabs to be found predominately in E facing slopes and some cross loading of others.  Some of these eastern aspects may be near the upper end of the “Moderate” rating definition.

Upslope snow showers are expected to give us about 1” (2.5cm) today associated with a wind shifting from the W to the NW and decreasing from 35-50 mph (56-80kph) to 20-35 (32-56kph).  I would expect a skilled traveler to find options to avoid new slabs and staying to old surfaces.  I will say that there is a good chance that post-holing through crust will be a real issue in numerous locations making travel rather heinous.  Cold air tonight with some clear periods will likely increase the faceting pace, increasing this problem.  Be particularly cautious while moving downhill as this issue has been the culprit of more than one broken leg on Washington.  Climbers should also be prepared for ice dams, or water under pressure, beneath the ice from yesterday’s rain and overnight freeze up.  An ice tool or crampon placement can release this with explosive results.  Bulges and rollovers are more likely to harbor these hazards than depressions.

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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 8:00a.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


Avalanche Advisory for Wednesday 2-1-2012

This advisory expires at midnight Wednesday 2-1-2012

Tuckerman Ravine has HIGH and CONSIDERABLE avalanche danger.  The Lip, Center Bowl, and Chute have High avalanche danger.  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. Right Gully, The Sluice, Left Gully, and Hillman’s Highway 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 conditions warrant.

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

Growing up in New England we never stopped hearing “…if you’re getting bored with the weather just wait a minute”.  Staying on our toes is a daily priority so we don’t fall asleep at the wheel.  On the drive in this morning I hit periods of rain hitting my windshield,…it was 22F degrees.  Yes rain, not freezing rain, rain.  This of course began freezing on contact.  It was pretty obvious a warm layer of air had infiltrated and was likely just above the 2000ft level.  2 minutes later I parked and 10 minutes later it was 37 degrees.  Temperature sensors up the mountain are now reading between 35 and 37 degrees from 2000 to 4500 ft. with elevations above and below getting warmer as mixing occurs.  So you’re likely wondering what does this mean for avalanches today.  Yesterday light snow fell through the day adding up to 3.4” (8.5cm) on the summit with W winds at about 40mph (64kph) through the morning and increasing to 50-60mph (80-96kph) gusting 70mph (112kph). This loaded E facing aspects directly and cross-loaded a number of other locations facing more S or N.  All of these slabs are now being affected by today’s warm precipitation and many areas in Tuckerman have already released wet loose avalanches. Hillman’s has a sizable debris pile in the dog leg down low with signs that the wet loose snow stepped down into an earlier 20m x 20m wind slab deposit.  Chute, Center Headwall, the Lip and Sluice all have wet loose debris. The period of freezing rain and rain in avalanche start zones, mostly between 4500 and 5200 will add load, weaken bonds and percolate into Tuesday’s cold slabs.  Weather models are expecting a total water equivalent between 0.1 and 0.25” (2.5-6.25mm).  For the slabs of concern in both Ravines this should fall as both rain and mixed precipitation before changing back to snow showers late this afternoon preceding a cold front hitting us around 5pm.   Expect snow instability to increase through the day with avalanche danger hitting a peak this afternoon before cold air begins to stabilize slabs.  Realize freezing temperatures won’t instantly reduce your risk, but it should end the instability trend.  A caveat to this is if we get both warmer temperatures and more rain than anticipated.  This would cause in an increase in free water percolation down to an impermeable lens below.  This scenario can delay the peak instability until after the freezing begins on the surface.  This is not a likely scenario today, but keep an eye on precipitation and ambient air temps in avalanche terrain today.  New snow loading through most of the day should be limited due to moderate wind speeds for Washington and a developing wet snowpack above treeline.  Late in the day snow showers and an increasing wind may begin snow transport to E aspects.  This shouldn’t add up to much for today’s date however Thursday may be a different story.  To summarize, expect a rapid rise in instability and the likelihood of naturally triggered avalanches due to rain and warm air.  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.  In addition to snow stability issues it will generally be an unpleasant day for mountain travel and a good one for the hot tub.   

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 wet and grabby for today and freezing up tonight.  Expect a frozen surface crust of a thickness and strength yet to be determined, but don’t expect it to be pleasant.

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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 8:20am. 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