Avalanche Advisory for Saturday March 22, 2014

Tuckerman Ravine will have HIGH and CONSIDERABLE avalanche danger later today. The Lip, Center Bowl, and Chute will have High avalanche danger. Natural avalanches are likely and human triggered avalanches are very likely. Travel in these areas and their runout zones is not recommended. Lobster Claw, Right Gully, Sluice, Left Gully, Hillman’s Highway, and the Lower Snowfields have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely in these locations. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential. The Little Headwall has Moderate avalanche danger. Natural avalanches are unlikely and  human triggered avalanches are possible.

Huntington Ravine has CONSIDERABLE avalanche danger. Natural avalanches are possible and human triggered avalanches are likely in these locations. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential.

AVALANCHE PROBLEM: Wind Slabs deposited yesterday are currently the primary avalanche problem this morning and will become the secondary issue this afternoon.  Storm Slabs and new Wind Slabs will couple to be the 2 main problems this afternoon as steady snow and high winds create significant new loading.  This afternoon combination, causing natural avalanche potential, will stress the already swollen slabs that exist currently.  It is a very heads up day! Avalanche activity that occurs late today from our most sizable snowfields, from the Lip south to the Chute, could step down to deeper slabs and be large.

WEATHER:  Moderate winds this morning from the WSW will shift to the WNW through the afternoon and increase from 40 to 90mph (64-144kph) by around dark.  As this ramp up occurs snowfall will increase with 3-6+” (7.5-15cm) possible between noon and 8pm. Temperatures will be cold as the mecury slides downward from the teens to below zeroF.

SNOWPACK:  Again, it is very important to pay attention to mother nature by watching exactly how weather plays out today. We have a classic sucker hole scenario setting up with pretty beneign weather conditions this morning, although with very respectable avalanche conditions.  I would call many areas solidly in Moderate and towards the upper end of the rating in places this morning.  This will change with the incoming weather event which will cause natural avalanches to be possible or likely, depending on location, later this afternoon.  If we do end up with snowfall at the lower end of the forecasted range, areas posted at High will be unlikely to get there.  However, even with 3″, all areas will at least reach Considerable due to winds moving from 50-80mph during the majority of daylight this afternoon.  Saying this, all weather indications are pointing at exceeding this lower accumulation range, so expecting dangerous to very dangerous avalanche late this afternoon would be a smart baseline.

Yesterday, high winds moved snow available in the alpine zone, and 2.5″ of new snowfall, in the Ravines.  Dodge’s Drop ran big and we would expect the Center Bowl of Tuckerman to have gone pretty large as well, but it is devoid of fracture lines this morning.  This tells me it likely went early and then reloaded, covering crowns.  Therefore, these large snowfields have fairly new slabs that are about 24 hours young, which in turn harbors new instabilites.  I feel confident of this mostly due to knowing the history of weather. Cold air on Friday, high winds, and new snowfall dominated by heavy riming/graupel undoubtedly have set up instabilities, but these conditions kept us from the field yesterday.  These slabs will be loaded with new weight today by snowfall that will come in on a moderate wind initiating as a soft slab. As winds increase slabs will become more dense, giving avalanche terrain an unstable upsidedown snowpack.  This early soft slab today will be the most likely weakness that will fail with the harder slab above that develops this afternoon, plausibily stepping down into the Friday slabs.  So as the day goes on, more and more redflags and alarm bells should be going off in your head! 

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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 10:09 a.m. 03-22-2014. A new advisory will be issued tomorrow.

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

2014-03-22 print

 

Avalanche Advisory for Friday, March 21, 2014

Expires at 12:00 midnight

Tuckerman Ravine has HIGH and CONSIDERABLE avalanche danger today. The Sluice, Lip, Center Bowl, and Chute have High avalanche danger. Natural avalanches are likely and human triggered avalanches are very likely. Travel in these areas and their runout zones is not recommended. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, and the Lower Snowfields have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely in these locations. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential. The Little Headwall has Moderate avalanche danger. Natural avalanches are unlikely and  human triggered avalanches are possible.

Huntington Ravine has CONSIDERABLE avalanche danger. Natural avalanches are possible and human triggered avalanches are likely in these locations. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential.

AVALANCHE PROBLEM: Wind slabs are the primary avalanche problem. Light, but continuous snowfall, brought another 6″ (15cm) of snow to the summit yesterday. Wind from the west and northwest loaded, and will continue to load, avalanche start zones as 1-3″ (2.5-7.5cm) more fall today. Very low visibility will make terrain assessment and safe route finding difficult. Rimed new snow may pile beneath steep terrain and will add to the Wind Slab problem.

WEATHER:  Spring is nowhere to be seen on Mount Washington. New snow, graupel and thick fog is limiting visibility to about 200′ now at Hermit Lake. The forecast indicates that these conditions are likely to continue through most of today as upslope effect wrings moisture out of the regional airmass before some clearing tonight.  Snow shower activity may diminish to some degree this afternoon, but I would not bank on much improvement in visibility today as NW wind in the 60-80 mph range with higher gusts continue to blow snow during the daylight hours.

SNOWPACK:  Very little field observations have been possible over the last 48 hours due to new snow and clouds. Brief clearing yesterday in Huntington revealed debris ran to the bottom of the current avalanche paths in South and Escape Hatch.  It is highly likely that Left Gully, Hillman’s and other avalanche paths on Boott Spur also avalanched due to early south winds. I mention this not only as a reminder that  this obvious red flag exists, but also that all of our avalanche tracks have grown rapidly over the past week or so. Avalanches today could also still step down to these deeper layers. New snow this afternoon may also fall on weak layers of large graupel that may have pooled in pockets beneath steep terrain. Recent trolling of social media indicates everyone is eager to get into the terrain to play in the new snow, but today is going to be a sketchy day to do it.  I would be respectful of avalanche paths throughout the area due to the probability of larger natural avalanches running out into lower angled terrain and crossing the approaches to lower rated terrain.  Spring is on hold for another day and into the foreseeable future.

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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 8:30a.m. 03-21-2014. A new advisory will be issued tomorrow.

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

2014-03-21 Print friendly

Avalanche Advisory for Thursday, March 20, 2014

This advisory expires  at midnight.

Tuckerman and Huntington Ravines 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. Avalanche hazard will remain elevated and even increase through the day.

AVALANCHE PROBLEMS: Storm Slabs will be the primary avalanche problem this morning. Wind Slabs, or problem #2, will continue to build due to increasing winds shifting from south to west. Travelling in avalanche runouts, like the floors of both ravines, is not recommended due to the risk and probability of natural avalanche activity.  Avalanches could be large and may step down into problem#3, older Persistent Slabs. Remember that increasing winds from the west this afternoon will have plenty of snow to build slabs and reload the gun barrels due to all the snow laying on the flat and expansive Alpine Garden.

WEATHER: Reduced visibility due to continued snowfall this morning, blowing snow all day and continued upslope snow showers in the afternoon will make it difficult to assess slopes and gauge your position relative to avalanche runouts. Southerly winds at 35-50 (56-80kph) mph will shift to the W and increase to 50-70 mph (80-112kph) in the early afternoon. Temperatures will fall back down to the mid teens. In addition to the 8.2″ (21cm) the summit has received so far another 1-3″ (2.5-7.5cm) is expected to fall through the day with a trace to 2″ (5cm) expected overnight due to upslope energy.

SNOWPACK: Temperatures at the start of this storm were in the low to mid teens F and winds were around 30-40 mph. Currently temperatures are approaching the mid-20’s F, much warmer than at the outset of snowfall. High winds blew in the 60’s mph, gusting in the 70’s, from midnight to 3am during the period of heaviest snowfall overnight. This wind direction and speed most heavily loaded gullies that face predominately north like parts of Odell, South, and the Escape Hatch.  Velocities also loaded and cross-loaded others like Pinnacle, Central, Chute, Left and Hillmans. Other areas received a blanket of new snow which has an equally disconcerting structure…lighter density snow with denser snow on top. The denser warmer snow is cohesive enough to create really touchy slabs prone to human triggering.  Continued snowfall and wind loading will create stress in the slab and increase the risk of human and natural triggering. These issues will increase on our main east facing slopes this afternoon as winds pick up and shift.  Of course, all of this speculation is based on weather data but if I were a betting man, I would lay my money on plenty of avalanche activity today, hopefully only of the naturally triggered variety. Remember that avalanche activity from the 18″ snowfall a week ago further smoothed and lengthened avalanche paths, buried many potential anchors points and generally brought all of our forecast areas into shape for larger avalanches to run in them. Today is a good day to find something else to do than travel in avalanche terrain on this fine, first day of Spring!

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 3-20-2014. A new advisory will be issued tomorrow.

Franklin S. Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-03-20 Print

Avalanche Advisory for Wednesday March 19, 2014

Expires at Midnight

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

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. North, Damnation, and Yale gullies have Low avalanche danger. Natural and human triggered avalanches are unlikely.

AVALANCHE PROBLEMS: Wind Slab created at the tail end of the weekend into Monday is the #1 problem today. Our largest snowfields with an E and SE facing component such as the Lip, Center Bowl, and Central Gully, as well as smaller cross-loaded slopes from W and NW winds, are the main locales holding these slabs. Deeper Persistent slabs are problem #2, and primarily exists due to faceting around the dominate crust layer buried at various depths depending on location. Other persistent weaknesses can be found, but play as a backseat problem compared to the aforementioned crust facets. All of these persistent problems could be the primary failure leading to an avalanche from human triggers. But a step down failure into these facets caused by an overrunning wind slab avalanche is more plausible.

WEATHER: Temperatures have been steadily climbing since Monday night and are expected to hit around 20F on the Washington summit today. Winds will pick up from the light winds we’ve had over the past day. W winds will shift to come from the S, and increase from 20 to 50 mph, bringing clouds this afternoon. Precipitation is anticipated to start in the form of light snow showers this afternoon as a prelude to the Winter Weather Advisory that comes into effect at 8pm tonight. We are expecting about 4” of snow overnight into tomorrow, perhaps mixing in with other frozen “wintry mix” particles. Below Hermit Lake we could see rain signifying the temperature regime will be very close to the freezing mark.

SNOWPACK: As Jeff referred to yesterday, high weekend winds have filled in the vast majority of crown lines causing some pretty intense variability around the Ravines. The main issue to pay attention to in your travels is the reactivity of the newest upper wind slabs. They will offer a variety of hardness based on being either exposed to the high winds, or being protected from them. I would mostly be looking out for two general wind slab issues. First would be thin hard slabs that could propagate a fracture into the deeper adjacent terrain leading to failure/avalanche. And secondly, softer slabs on steep slopes near terrain features that protected loading snow from getting wind pounded. These near surface wind slab issues are followed by keeping a keen eye for “persistent” problems presenting as deeper weaknesses. Spatial variability will make it difficult to make assessments in one location and extrapolate the findings to another. Frequent stability tests are prudent.

Early solar gain will play a bit more of a role than it did yesterday for south facing slopes as temperatures get quite a bit warmer than Tuesday. However, as we move into the afternoon, winds will come from the south and increase, which will help cool these southerly aspects. Additionally, thin clouds will increase in thickness dramatically limiting potential heat. This brief heat should help the snowpack stabilize a bit, but not push too hard causing instability. The big issue late today and tomorrow is the snow coming on S and SW winds, shifting W tomorrow and increasing. Expect a loading event through tomorrow with an elevated avalanche danger.

Please Remember:

1. 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. 2. Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast. 3. 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 8:33a.m. 3-19-2014. 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

2014-03-19 Print

Avalanche Advisory for Tuesday, March 18, 2014

This advisory expires at 12:00 midnight.

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

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 trigged avalanches are possible. North, Damnation, and Yale gullies have Low avalanche danger. Natural and human triggered avalanches are unlikely.

AVALANCHE PROBLEMS: Recently formed wind slab is the easiest avalanche problem to recognize today. These can be found in the uppermost layers of the snowpack in areas sheltered from the weekend’s W-NW winds. This includes the larger snowfields such as the Lip, Center Bowl, and Central Gully as well as smaller areas where cross-loading occurred despite not being directly in the lee of W or NW winds. Persistent slabs are less easily recognized, but should still be in your mind as a serious avalanche problem. These primarily exist due to a crust layer buried under much of the upper layers, though other weak layers may come into play. The persistent slab problem might be triggered either by a smaller release of the upper wind slab layer or by you simply finding the right weak point in the snowpack. This could result in a large damaging avalanche.

WEATHER: What to say about the weather today?? 15-30mph (24-48kph) winds and summit temperatures reaching the teens F (-9C)…this sounds like a fantastic WINTER day. Don’t let the sunshine fool you, it ain’t spring just yet. I’d recommend Cranmore Mountain today for those who don’t care to travel with avalanche gear. Those south-facing slopes in the valley will probably warm up quite nicely, especially compared to up here.

SNOWPACK: As mentioned above, the first thing you need to be looking at today is the uppermost layers in the snowpack. After last week’s storm, we received several inches of additional new snow. Early on Sunday morning, winds kicked up with gusts almost to 100mph. The resulting wind loading filled in many of the crown lines left by previous avalanche activity, as well as building slab in areas that had already been reloaded. The second thing to assess for is the underlying weaknesses, aka persistent slabs. Spatial variability will make it difficult to make assessments in one location and extrapolate the findings to another.

I expect solar energy to be a favorable player in today’s stability on aspects that are in the sun. While temperatures shouldn’t be rising high enough to moisten the surface snow, the solar gain should help to stabilize the wind slab that we are concerned about. The more a slope faces into the sun, the stronger this effect will be. Also, the shallower the wind slab layer, the stronger this effect will be. For example, do not expect similar stability in the Lip if you just climbed and assessed the snow in Right Gully. RG gets more direct sun and has thinner, smaller slab problems; the Lip is more oblique and will have deeper wind slab layers. Also, do not expect the solar gain to do much for stabilizing the persistent slabs. These will need more than yesterday and today to fully stabilize 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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 8:30a.m. 03-18-2014. 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

2014-03-18 print friendly

Avalanche Advisory for Monday, March 17, 2014

Expires at 12:00 midnight

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger today. The Sluice, Lip, Center Bowl, and Chute have Considerable danger. Natural avalanches are possible and human triggered avalanches are likely in these locations. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, and the Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Heightened avalanche conditions on specific terrain features exist. Evaluate snow and terrain carefully to identify features of concern. 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 Escape Hatch have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible. Heightened avalanche conditions on specific terrain features exist. Evaluate snow and terrain carefully to identify features of concern. North, Damnation, and Yale have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Wind slabs are the primary avalanche problem. Loading that occurred since the widespread avalanche cycle following Thursday’s storm has continued to produce wind slab instabilities in both Ravines.  In the past 36 hours an additional 4-5″ (10-12cm) of snow fell with cold temperatures slowing stabilization. This cold air created the potential for Persistent Slabs to become our second avalanche problem due to weak snow deeper in the snowpack. The potential for larger avalanches has increased as our terrain has filled in and slabs have become more continuous.

WEATHER:  Good visibility under thin, high clouds and cold temperatures dominate the forecast today. Northwest winds in the 45-55mph (70-85kph) range with higher gusts will limit suntanning options. High temperatures will be around zero F (-18C). Winds should diminish some as well through the day.

SNOWPACK:  As mentioned earlier, wind slab developed over the weekend in much of our forecast area. Lee areas like Lip through Chute and crossloaded areas in Pinnacle through Escape Hatch  have the most widespread areas of this newer windslab which is likely to be the most reactive to triggering by a person. Areas rated Considerable are rated so due to the potential size and higher likelihood of human triggering, not due to an elevated probability of a natural avalanches. Essentially our ratings are hovering on the Moderate/Considerable line due to several factors. Before the snow fell Saturday night and early Sunday morning a surprising amount of wind blown snow was transported by westerly and southwesterly winds, refilling slopes and covering the many crown lines from the widespread avalanche activity on Thursday. Field work Friday in the Sluice and Left Gully area showed the slabs that developed during and after the storm were reactive (STE, CT12-14, 70-80 cm down) and would propagate a crack (ECTP 11,12). Though the spatial variability is obviously a problem here in our forecast area, those kind of results can be expected in a lot of areas. If you are out and about today, be wary of firmer slabs that feel strong underfoot. The finger to pencil hard wind slabs are strong but brittle so finding the trigger point could result in a larger avalanche than expected as a crack can propagate through a much thicker slab than the point at which it breaks. In other words, the surface wind slab and scattered softer slabs are just the tip of the proverbial iceberg. With good visibility and longer daylight hours, you will have the opportunity for careful assessments, terrain choices and safe travel techniques.

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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 8:35a.m. 03-17-2014. A new advisory will be issued tomorrow.

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

2014-03-17 Print friendly

Avalanche Advisory for Sunday March 16, 2014

Expires at Midnight

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger today. The Sluice, Lip, Center Bowl, Chute, Left Gully, and Hillman’s Highway have Considerable danger. Natural avalanches are possible and human triggered avalanches are likely in these locations. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential. Lobsterclaw, Right Gully, the Lower Snowfields, and the Little Headwall have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.

Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger. Central Gully has 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 are essential.  All other forecast areas have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible. Heightened avalanche conditions on specific terrain features exist. Evaluate snow and terrain carefully to identify features of concern.

AVALANCHE PROBLEM: Wind slabs are the primary avalanche problem. Loading that occurred since the widespread avalanche cycle following the Thursday storm has continued to produce wind slab instabilities in both Ravines.  In the past 18 hours an additional 3-4″, depending on the specific snow plot observed, of snow has contributed substantially to the current wind slab problem.  Expect variable conditions from firm older hard slab to newer soft slab currently developing in sheltered locations.

WEATHER:  Temperatures have been falling overnight and will continue to do so bottoming out around -15F (-26C) later today.   Winds will stay high today, potentially gusting over 100mph.  The current trend has been decreasing from a 99mph peak early this morning to a current of about 70mph.  As the high builds in, this will change to an increasing trend again this afternoon. New snow will taper as this occurs, but expect blowing snow to effect visibility for most of the day.

SNOWPACK:  Another “heads up” day exists for mountain travelers in avalanche terrain today.  Overnight, the mountain has received close to 4″ (10cm) on a WNW and W wind from 60-95mph.  This has likely caused a fair amount of spatial variability, due mostly to the high wind speeds.  Expect to find some areas devoid of new snow while the most protected slopes, with large terrain features, will have soft new unstable slabs particularly on slopes exceeding 40 degree angles facing E and SE.  This diversity will likely continue to become more chaotic if the increasing wind velocities play out this afternoon.  In our forecasters meeting this morning we were straddling the fence between Moderate and Considerable and decided Moderate most accurately describes today’s problems for some areas.  In Huntington’s Pinnacle, Odell, and South; and Tuckerman’s Lobster claw, Right Gully, and Lower Snowfields instabilities definitely exist and should tap all your safe travel skills to negotiate them safely. Ultimately, we decided to call them Moderate due to today’s high winds creating variable, inconsistent surfaces from scoured to soft slab pockets.  In Huntington, I would anticipate new snow to have sluffed off steep ice flows and would pay attention to unstable slabs beneath ice pitches in Pinnacle, Odell, and certainly Central which is posted at Considerable.  Of course, all of today’s new slab problems have loaded over lingering instabilities from Thursday and Friday.  Yesterday’s warm temperatures did help the stabilization process a bit before new snow began, but this warming did not penetrate deeply.  This warming, followed by very cold air today, has certainly developed a near surface snowpack temperature gradient that we’ll need to watch.  Expect to see a persistent slab discussion over the next couple of 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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 8:35a.m. 03-16-2014. 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

2014-03-16 Print

 

Avalanche Advisory for Saturday, March 15, 2014

This advisory expires at 12:00 midnight. Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger today. The Sluice, Lip, Center Bowl, and Chute have Considerable danger. Natural avalanches are possible and human triggered avalanches are likely in these locations. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential. 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. Heightened avalanche conditions on specific terrain features exist. Evaluate snow and terrain carefully to identify features of concern. AVALANCHE PROBLEM: Wind slabs are the primary avalanche problem. Widespread avalanche activity in the past 36-48 hours are one indication of potential instability. Field work yesterday revealed most slopes had reloaded with wind slabs or our second avalanche threat which is piles of sluff debris.  Areas where these firm slabs exist could be triggered by a load of skiers or climbers finding a thin spot in the slab and would likely result in an avalanche large enough to bury a person. WEATHER:  Overcast, flat light and potential snow showers today will challenge visual assessments. West winds around 55 mph will increase late in the day towards 80 and temperatures will fall from their balmy position at 20 F on the summit, 39 F at Pinkham Notch, into another unseasonable deep freeze.  SNOWPACK: Continued reloading occurred yesterday due to blowing snow with a shifting wind to the SW. Though temperatures warmed yesterday increasing the stabilizing process to some degree, it is unlikely this warming reached deep enough into the snowpack to create bonds where these deeper weak layers exist. Yesterday, Chris, Joe and I counted dozens of crown lines from Boott Spur through the Tuckerman cirque and over to the slopes beneath Lion Head. These crowns ranged in size from a foot to over 5 feet deep visible even after considerable reloading. Crowns in Huntington were also visible with significant debris beneath South with other piles scattered through the Fan and beneath Harvard ice bulge. Avalanches due to the failure of a number of weak layers from mid-storm snow, ice crust, and a layer of needle forms from a couple of weeks ago. Ice crust from the January 21 rain event was also a player and was ripped up by avalanches. Chunks of this crust was visible in debris as well as where it was blown across the floor and deposited on the surface. The trigger during the storm was the increased load of snow blown in. Today, climbers and skiers could be the load and trigger without careful routefinding.  Avalanche danger in Right Gully and Lobster Claw is often quick to fall due to a combination of aspect, terrain features and  compaction, but these areas still require solid skills to pass through safely. The Lower Snowfield area has filled in due to substantial avalanching and sluffing from above and looks an awful lot like it did prior to the skier triggered avalanche last April under similar conditions.  While Damnation and North in Huntington appeared to be near the lower end of Moderate, I would stay heads up on all the routes there due to the consequence of triggering what are potentially hard slabs of the larger variety. Not many slope testers have travelled through yet. Temperatures near and below 0F in our forecast areas tonight will continue destabilizing areas with buried temperature crust and associated facet growth. For more info check out a Youtube post from yesterday. 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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 8:30a.m. 03-15-2014. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger USDA Forest Service White Mountain National Forest (603) 466-2713 TTY (603) 466-2856 2014-03-15 Print friendly

Avalanche Advisory for Friday 3-14-2014

Expires at midnight

Tuckerman Ravine has CONSIDERABLE avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely.  Dangerous avalanche conditions exist. Conservative decision making is essential.

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

AVALANCHE PROBLEMS: Wind Slab is the avalanche problem today.  Wind Slabs that developed through the recent storm and new wind slabs that are developing this morning are the immediate problem.  This afternoon, winds will increase and new snowfall will combine together to present another fresh round of wind slab loading over cold unstable slabs.  Fresh fracture lines are visible everywhere.  This is the #1 sign that instabilities exist and communicating to you that more potential exists.

WEATHER:  This storm gave us 18”(45cm) at Hermit Lake and is a good general average for the Mountain.  Today, cold NW winds will shift to the W and increase from 50 to 80mph.  Temperatures will warm from -15F to the + teens F late today as clouds intrude, drop, and bring some light snow.

SNOWPACK: Today is a great day to keep it simple and focus on the bulls-eye dataFracture lines or debris are visible in most avalanche paths, many being impressive.  Some fractures are deep and beat up signifying they happened earlier in the event.  In others, they are clean, thin, and crisp indicating they occurred much more recently.  Our terrain made a tremendous jump forward with this storm growing avalanche prone slopes substantially.  We’ll post pictures later.

In short, 18” of snow, winds gusting 80+ mph from the W and NW, and cold air in place has allowed unstable slabs to exist in many areas.  Some locations with deep fractures have obviously released their unstable slabs, although a number of them have seen some reloading.  Other locations are presenting smooth and engorged, holding their slabs like a gluttonous pig.  Today is a major heads up day and traveling safely will tax your safe avalanche experience and skills.  I believe a human triggered avalanche is likely on many Tuckerman’s slopes, hence the Considerable rating.  In Huntington, forecast areas are solidly in Moderate at the upper end of the rating definition, particularly from Central through South.  Some current active loading, light snow late in the day, and increasing wind keeps natural avalanches a potential in both Ravines.  In Tuckerman, they are more possible, but would keep it in your mind as a potential reality in Huntington as well.  Although I would consider naturals unlikely in Huntington they are not completely out of the question. Pay attention to natural loading and stay heads up to changing conditions.

With cold unstable slabs and the weekend on the horizon we are nervous.  We are changing beacon batteries, charging the Recco, changing out to big shovels, and tuning up the dog.  Seriously, it’s a heads up weekend!  Check out the Weekend Update this afternoon.     

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 900 a.m. 3-14-2014. A new advisory will be issued tomorrow.

Christopher Joosen, Snow Ranger
USDA Forest Service

2014-03-14

Avalanche Advisory for Thursday, March 13, 2014

This advisory expires  at midnight.

Tuckerman and Huntington Ravines have HIGH avalanche danger.  Natural avalanches are likely and human triggered avalanches are very likely. Large avalanches are expected on a variety of slope aspects and angles. Very dangerous avalanche conditions exist and travel in avalanche terrain is not recommended.

AVALANCHE PROBLEMS: Storm Slabs from the 14” snowfall will be the primary avalanche problem this morning. The size and destructive power of avalanches today will increase rapidly as Wind Slabs build due to increasing Northwest winds. Travelling in avalanche runouts, like the floors of both ravines, is not recommended due to the risk of natural avalanche activity. The rescue cache (Connection Cache) just as you enter Tuckerman could be overrun by avalanche debris. Avalanches will be large and may even step down into older persistent weak layers and grow even larger.

 WEATHER: As of midnight this storm system has delivered 14” of 10% average density snow to the summit of Washington. This was delivered on a general S and SE wind, peaking in the 40’s mph. Since midnight light snow has continued and should give us another 2-4” today.  Currently, very low velocities have begun the clockwise shift towards the NW where they are forecasted to sit today and start screaming.  Through the day, winds will build and are anticipated to gust over 80 mph late in the day.  Expect zero visibility as a large volume of alpine snow becomes airborne and transports to SE and E facing slopes.

 SNOWPACK: Yesterday’s snow and new snow today on these forecast winds makes a snowpack discussion pretty much irrelevant when it comes to making travel decisions today.  The storm started out fairly cold with some wind and then turned warmer and wetter without much wind and then turned cold again. This means we have a relatively light layer of wind affected snow with denser snow above. Add to this a load of wind slab as West then Northwest wind ramps up with additional new snow today and widespread avalanches are the result. To sum up, today is a good day to find cold snow somewhere on lower angled terrain in the woods with a careful eye of where avalanches from above could run.

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 7:00am 3-13-2014. A new advisory will be issued tomorrow.

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

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