Avalanche Advisory for Sunday, February 19, 2017

This advisory expires at Midnight.

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

Tuckerman Ravine has MODERATE and LOW avalanche danger today.  Lobster Claw, Right Gully, Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain carefully. Left Gully, Hillman’s Highway, Lower Snowfields and Little Headwall have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Today, the avalanche problem will differ depending on the slope aspect. The likeliest hazard today will be Wet Loose avalanches. These will remain a threat until the snowpack refreezes tonight. Slopes of most concern for wet loose will be S and SE facing slopes such as Lobster Claw, Right Gully, and Sluice. Other slopes may have the potential for wet loose depending on how long temperatures remain warm. Wet Slabs may come into play today if the warm temperatures penetrate deep enough into the snowpack or if thinner slabs are encountered. Again, this is most likely on S facing slopes. Areas that remained in the shade yesterday and have more recently started to warm still harbor characteristics of Wind Slab. While less likely that these would be triggered by a human than a wet loose slide, the size and destructiveness of a wind slab avalanche today would be far greater.

WEATHER: Temperatures on the Summit have stayed over 20F for 24 hours and hitting the freezing mark yesterday for a few hours in the afternoon. Currently, it is 24F on top and 35F at Hermit Lake. Today, the temperature should approach 30F on the Summit and remain there until mid-afternoon. Winds will decrease slightly from the current W 75mph to the 60mph range and shift to the NW. Summit fog will likely remain for the day with periods of clearing in the Ravines possible. A chance of snow (trace to 2”) exists today and tonight.

SNOWPACK: Strong winds Friday and Saturday transported much of the snow that fell over the past week. Evidence of this wind can be seen as scoured areas like the north wall of Huntington, smoother wind loaded slopes like the Lip and Center Bowl area of Tuckerman, as well as large sastrugi formations in Odell, South, and Left Gully. Temperatures around the freezing mark yesterday along with periods of sunshine allowed the sunnier (south facing) slopes on both ravines to warm. This warmth seemed to be limited to the top 10cm of the snowpack and was not creating any issues yesterday. Areas that saw no or very little sun remained cold. Overnight temperatures dropped very little, leaving us this morning with the same 10cm of wet snow. Today, temperatures will increase slightly, allowing this warmth to continue penetrating into the snowpack. With forecast cloudy skies, this likely will not get very deep, keeping the main hazard for skiers and climbers to wet loose avalanches. If the clouds break for a period and the snow receives rapid solar gain combined with the warm temperatures, the potential for wet slabs will increase. As the uppermost wind slab is quite thick in places, this is unlikely; however if the skies clear, this may rapidly change.

With a busy weekend in progress, be prepared for crowds. Having an alternate travel plan in mind will make today safer.

 

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  8:15 a.m., Sunday, February 19, 2017. A new advisory will be issued tomorrow.

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

2017-02-19

Avalanche Advisory for Saturday, February 18, 2017

This advisory expires at Midnight.

Huntington Ravine has MODERATE and LOW avalanche danger today. Central Gully has Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. All other forecast areas in Huntington Ravine have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has MODERATE and LOW avalanche danger today. Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain carefully. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, Lower Snowfields and Little Headwall have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

 AVALANCHE PROBLEM: Wind slabs that developed over the past 48 hours will be the primary stability concern today. These will be firm and stubborn in most areas.  Beware of smooth areas of wind slab in the steepest areas or in any convex area you might find. Though these wind slabs will be tough to trigger, it is not too much of a reach to imagine someone finding the right thin spot in steep terrain. While an active avalanche cycle ripped out the soft weak failure layer in most of our larger forecast areas, most slopes have not yet been tested by climbers or skiers so don’t forget to dig and poke around when entering the terrain.

WEATHER: It is currently 26F at Hermit Lake with calm winds and overcast skies. A warm front pushing through this morning will allow skies to clear and temperatures to warm later today to a balmy lower 30’s F. Partly cloudy conditions may even allow some sunshine to warm things further. Winds will increase through the day and reduce any concerns for the incoming sunshine to warm and weaken the snowpack. A cold front will approach rapidly late this afternoon and change things dramatically. Wind will increase to 65-85mph with gusts to 100 mph by evening. It’s a good day to have a strong headlamp and clear goggles just in case.

SNOWPACK: Northwest winds yesterday continued to erode surface snow. Heavily textured (sastrugi) snow and avalanche debris share the stage with smooth areas of firm but edgeable slab. More wind sheltered terrain like Lobster Claw and Right Gully are mostly smooth but don’t share the terrain factors that nudge areas like the Sluice and Lip into a higher danger rating. Hillman’s and Left Gully have the usual mix of surfaces from wall to wall making it possible to choose your travel surface. Areas of ice crust from the most recent sleet event are even exposed in a few locations due to wind scouring. In other areas of Tuckerman, the ice crust was ripped up by avalanche activity.

It’s the start of President’s Day weekend. With so many people around, please be respectful of people below you and be on the lookout for hazards overhead.

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  8:25 a.m., Saturday, February 18, 2017. 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

2017-02-18

 

 

Avalanche Advisory for Saturday, February 18, 2017

This advisory expires at Midnight.

Huntington Ravine has MODERATE and LOW avalanche danger today. Central Gully has Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. All other forecast areas in Huntington Ravine have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has MODERATE and LOW avalanche danger today. Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain carefully. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, Lower Snowfields and Little Headwall have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. 

AVALANCHE PROBLEM: Wind slabs that developed over the past 48 hours will be the primary stability concern today. These will be firm and stubborn in most areas.  Beware of smooth areas of wind slab in the steepest areas or in any convex area you might find. Though these wind slabs will be tough to trigger, it is not too much of a reach to imagine someone finding the right thin spot in steep terrain. While an active avalanche cycle ripped out the soft weak failure layer in most of our larger forecast areas, most slopes have not yet been tested by climbers or skiers so don’t forget to dig and poke around when entering the terrain.

WEATHER: It is currently 26F at Hermit Lake with calm winds and overcast skies. A warm front pushing through this morning will allow skies to clear and temperatures to warm later today to a balmy lower 30’s F. Partly cloudy conditions may even allow some sunshine to warm things further. Winds will increase through the day and reduce any concerns for the incoming sunshine to warm and weaken the snowpack. A cold front will approach rapidly late this afternoon and change things dramatically. Wind will increase to 65-85mph with gusts to 100 mph by evening. It’s a good day to have a strong headlamp and clear goggles just in case.

 

SNOWPACK: Northwest winds yesterday continued to erode surface snow. Heavily textured (sastrugi) snow and avalanche debris share the stage with smooth areas of firm but edgeable slab. More wind sheltered terrain like Lobster Claw and Right Gully are mostly smooth but don’t share the terrain factors that nudge areas like the Sluice and Lip into a higher danger rating. Hillmans and Left Gully have the usual mix of surfaces from wall to wall making it possible to choose your travel surface. Areas of ice crust from the most recent sleet event are even exposed in a few locations due to wind scouring. In other areas of Tuckerman, the ice crust was ripped up by avalanche activity.

It’s the start of President’s Day weekend. With so many people around, please be respectful of people below you and be on the lookout for hazards overhead.

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  8:10 a.m., Saturday, February 18, 2017. 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

Yet another avalanche cycle…

A look into Tuckerman Ravine following the 8″ snow which fell on calm winds on Feb 15/16.  Slowly increasing NW winds into the 50-60 mph range Thursday afternoon ramped up higher through the night. Here’s a look at the avalanches that resulted and the terrain as of Friday at around 1pm. 68″ of snow has fallen in February with 94″ on the ground at the snow plot near Hermit Lake.

 

Note the crown line low on the slope below Chute. Ice crust was evident in several areas in or near debris.

 

Lobster Claw and other south facing lines are top to bottom.

 

Right Gully has really filled in and Sluice appears to have released a pretty good sized avalanche into Lunch Rocks if not in yesterdays storm then during the last storm.

 

It appears that most of Chute through Center Bowl and Lip avalanched once around the same time and then reloaded. Another crown was visible near the Tuckerman Trail traverse through the Lip as well.

 

Lunch Rocks is still visible but just barely. The upper crown line in the Lip is heavily eroded which indicates it failed early on. It’s just visible in the upper right.

 

Left Gully and a small slide below Chute Variation and the Elevator Shaft.

 

Avalanche Advisory for Friday, February 17, 2017

This advisory expires at Midnight.

Huntington Ravine has MODERATE avalanche danger today. All forecast areas in 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 to identify features concern.

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger today. Sluice, Lip, Center Bowl, and Chute have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Careful snowpack evaluation and cautious route-finding is essential. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, Lower Snowfields and Little Headwall have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible.  Evaluate snow and terrain carefully.

AVALANCHE PROBLEM: Wind slabs that developed overnight are continuing to build but to a more limited degree as wind abates and available snow is depleted. Beware of smooth areas of wind slab, even in moderate rated areas. In these locations, wind slabs are likely to be firm and somewhat stubborn but also potentially large so enter any avalanche terrain cautiously today. Considerable rated areas continuing to be loaded at greater rate and contain larger areas of wind slab.

WEATHER: Winds are currently blowing from the NW at 68mph on the summit. Wind will remain generally from the NW and gradually diminish through the day, though the currently limited wind transport of snow into avalanche start zones will continue. The temperature at the summit will rise from where it sits at 5F to the teens F. The summit recorded around 5” of snow in the past 24 hours and around 22” since February 15. Total snowfall recorded on the summit this month is 68” with 94” at the snow stake on the snow study plot at Hermit Lake.

SNOWPACK: Avalanche activity yesterday and overnight has once again altered the lay of the land in our forecast area. Northwest winds seemed slow to ramp up yesterday but clear signs of rapid wind loading were obvious from my vantage point in the afternoon from Wildcat. A wide crown exists in the Center Bowl and Lip area, the upper start zone of the Lip, near the Chute, and in Duchess. Most of these crown lines are reloaded making it pretty clear that reloading occurred mid avalanche cycle. A mix of heavily textured sastrugi as well as large smooth pillows and even some older ice crust exists in various amounts through the terrain depending on aspect and exposure. Northern gullies in Huntington are mostly scoured and wind hammered though the approach from the Fan is large and smooth and is probably best avoided. Similarly, Lip, Center Bowl over through the Chute have been reloaded are seem somewhat ripe for an avalanche. Crossloaded areas in the upper right of Hillmans are a concern though sastrugi dominates the surface mid-slope.

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  8:15 a.m., Friday, February 17, 2017. 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

2017-02-17

Avalanche Advisory for Thursday, February 16, 2017

This advisory expires at Midnight.

Huntington Ravine and Tuckerman Ravine will have HIGH avalanche danger today. All forecast areas will have HIGH avalanche danger. Natural avalanches are likely and human-triggered avalanches are very likely. Very dangerous avalanche conditions exist. Travel in avalanche terrain is not recommended. The only exception to this rating is the Little Headwall which may rise to Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible there.

Very dangerous avalanche conditions will exist today. Avoid all avalanche terrain later today as wind speeds begin to increase. Large avalanches in many areas will be likely.

AVALANCHE PROBLEM: This morning, there is Considerable danger of Wind Slab and Dry Loose avalanches from 8” of new snow last night. Though this new snow was deposited on generally light winds, some gusty conditions mid-storm may have created a cohesive slab in some areas. Much larger and more dangerous Wind Slab avalanches will be likely this afternoon as wind from the northwest ramps up. These slabs will release naturally and most likely run far into flat areas like the floor of Tuckerman Ravine and the wooded areas in Huntington. Our avalanche paths have grown very large in the past week. The size of these slopes, the available new snow, and the high winds have set the stage for very dangerous avalanche conditions today. Travel in avalanche terrain is not recommended.

WEATHER: 7.5” (19cm) at Harvard Cabin and 8” (20.5cm) at Hermit Lake (.95 SWE) of new snow fell in the past 24 hours on predominately light and variable winds. SSE gusts to 47mph occurred yesterday afternoon for a couple hours. The main weather factor driving our avalanche danger rating today will be the steadily increasing wind from the north which will shift to the northwest and blow at speeds that will easily load new snow into our start zones. Warm, moist air hanging around the North Country should provide ample moisture for upslope snowfall in the 2-4” range. This will challenge visibility and add to the new load of snow.

SNOWPACK: Our active weather pattern has grown the avalanche terrain in our forecast areas to near epic proportions. Avalanche activity from the 20”+ nor’easter 4 days ago deposited debris darn close to the maximum extent in most of our avalanche paths. Earlier avalanche activity from the Center Bowl ripped up the old ice crust and accessed some of the sleet deposits from the mixed precipitation storm a couple of weeks ago. Wind slabs were found to be on the softer side in some locations on Tuesday, so the possibility exists that today’s new large wind slabs will step down into these older slabs and add to the problem. If you are attempting to poke into the terrain this morning before the wind ramps up, I would definitely be on the lookout for a cohesive layer within this new snow. Gusty mid-storm winds could have created enough cohesion to cause propagation in otherwise loose snow. Crossing avalanche paths in our forecast area and entering Tuckerman or Huntington Ravine will put you in the crosshairs for multiple avalanche paths today.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted  8:00 a.m., Thursday, February 16, 2017. 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

2017-02-16

Avalanche Advisory for Wednesday, February 15, 2017

This advisory expires at Midnight.

 

All forecast areas of Huntington and Tuckerman Ravine 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 are essential today. The only exception to this is the Little Headwall which has Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: The avalanche problem this morning is Wind Slab. We are starting the day at the lower end of our Considerable rating, with some areas like the north walls of both ravines closer to Moderate. All areas have wind slab that formed from the Sunday-Monday storm that in places is quite thick and has a clear upside-down composition. As the day progresses and snow accumulates, we will see Storm Slab form and all areas move solidly into Considerable. As snow accumulates, be on the lookout for Loose Dry avalanches. By the time this advisory expires at midnight, many places like the Hillman’s, Left Gully, South and Odell will be pushing the higher end of the Considerable rating.

WEATHER: Twenty-four inches (24”) of snow fell Sunday afternoon into Monday. Winds shifted around the compass during this storm. After a clear day yesterday, snow showers began around midnight with just under an inch accumulating by this morning. Winds are currently from the S at 30mph and will remain there for most of the day, possibly shifting to the SW this afternoon before moving to the SE this evening. Snow showers will get heavier as the day continues, with up to a foot (12”) of new snow by tomorrow morning. Winds tonight will shift through the E to the N and increase to 45mph.

SNOWPACK: Widespread wind slab formed at the end of the previous storm. Several avalanche cycles have come and gone with most crowns refilling due to wind loading. In addition to the wind slab, large areas of debris exist in the approaches to gullies. Mid sections of some gullies that saw smaller avalanches are scoured down to the old breakable crust from last week, however, areas that had large and very large avalanches saw this crust ripped out and due to their more wind sheltered locations, are now loaded with large areas of wind slab. The upper portion of the wind slab was mostly fist to four-finger hardness (F-4F) with a potential failure layer of fist hard snow underneath. Snow today will arrive on south winds, allowing the southern gullies to see the most loading of new wind slab. As the past storm allowed many slide paths to run large and rarely formed paths to develop, approaching any gully in our terrain will now require crossing under several avalanche paths. Limited visibility today will create difficult safe navigation.

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  8:30 a.m., Wednesday, February 15, 2017. A new advisory will be issued tomorrow.

Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2017-02-15

After the Storm

There is no doubt we’ll be talking about this storm for years. It seems like everyone experienced some of the greatest skiing on the east coast in a long time. That’s what 11.6″ of 7.6% density snow followed by 12″ of 8.5% snow will give you. The real question for us was what happened in the Ravines.

You may have noticed, we put the Extreme slats up yesteday. Frank, Ryan and I talked long and hard Sunday and Monday about what this means. Here’s a bit of our thought process. First, the likelihood of avalanches. That was an easy one. Yesterday morning, with the facts we had, we were certain that avalanches would take place. Second, travel advice. High danger says Travel in avalanche terrain is not recommended. Extreme says Avoid all avalanche terrain. Again, the choice seemed easy to go to Extreme. Third, the size and distribution. This is always the though choice for us. Extreme says Large to very large avalanches in many areas. We always debate how big our slides are. Certainly not as big as they can get out west our abroad, so we have to keep it relative to our scale. A very large avalacnhe in my mind is the Bowl-alanche, when something in the Tuckerman Headwall triggers from Sluice over to the Chute. We get these occasionally, and in my mind, this is very large. So can we have this size elsewhere? Talking it out Monday morning, the storm had been delivering heavy snow on ESE winds and was just shifting counter-clockwise to the NW on mild winds for our standards. This had the potential to heavily load the north wall in Huntington as well as the Fan, creating conditions that could allow the north wall to go as one big slide. Again, this is very large in my mind. As to areas that receieved the High rating yesterday, our thought was that the size avalanche in those would not reach the very large size, partly due to the size of the gully, but also partly due to a lesser degree of wind loading taking place in these areas.

To further make Monday’s forecast trickier was the fact that this storm was not coming in on strong winds. When winds rip and we get this amount of snow (24″), the wind slab can grow very thick before finally releasing. Think very large. On the winds this storm was arriving on, we were thinking we might see a several cycles of softer slab rather than fewer cycles of firmer slab. Several medium to large avalanches rather than one cycle of very large avalanches was a possibility with this storm.

With all this in mind, I was very happy to see bluebird skies on my drive north to Pinkham this morning. A perfect opportunity to see what happened and hopefully confirm what we thought. The following is documentation of the carnage Brian and I found today. Every gully we forecast slid (except the Little Headwall) including multiple unnamed features and snowfields. Both Ravines had debris travel the farthest of the season. Particularly noteworthy, Hillman’s Highway jumped the dogleg. We are in the midst of a winter that is shaping up quite well.

Huntington: South and Odell

Huntington Ravine

The North Wall of Huntington

An example of the widespreadness of the avalalanche cycle. This unnamed gully is to looker’s left of Escape Hatch. It was one of the few visible crown lines that had not reloaded.

An impressive amount of snow in Tuckerman.

Left Gully and the Chute. Note the pillow lingering in the upper reaches of Left.

Lobster Claw, R Cubed, Q-Bert, and the Fourth Dimension. These gullies all grew substantially from the storm.

Lip, Sluice, and Right Gully, Note the crown in the Lip from early Tuesday morning.

Brian feeling very exposed on the floor of Tuckerman which has grown significantly.

The Boott Spur Ridge looking very filled in. The Lower Snowfields grew dramatically.

Hillman’s Highway from the debris tha jumped the dogleg.

The Lower Snowfields and Hillman’s from the Tuckerman Ravine Trail. Wow.

 

Back to the original thought of when do the Extreme slats get posted. We were certain that avalanches would take place and today we saw signs of at least one cycle in every forecast area. Travel advice of Avoid all avalanche terrain was appropriate. As to the size and distribution, we saw signs of large and very large avalanches in many areas. The feedback Brian and I received in the field today was great. We take our ratings seriously and validation of our ratings is always a great thing to see.

If this wasn’t enough, be sure to check out the weather forecast for tomorrow. While the snow totals are going down, we’re still looking at upwards of 12″ by Thursday morning with increasing winds. It might not be Extreme, but I’m excited for the high pressure moving in on Friday and getting visibility of more avalanches.

See you on the hill.

Helon.

Avalanche Advisory for Tuesday, February 14, 2017

This advisory expires at Midnight.

Huntington Ravine has MODERATE avalanche danger today. All forecast areas 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 to identify features of concern.

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger today. Sluice, 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 are essential. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway and Lower Snowfields 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 to identify features of concern. Little Headwall has Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Wind and a barrage of snow over the past 36 hours formed Wind Slab in our terrain. The weather today will not increase the avalanche danger. The area of greatest concern today will be the Sluice through Chute in Tuckerman. A fresh crown in the Lip is a sign that this area is on the edge of shedding its most recent layer of wind slab and may be reactive to a human-trigger. All other forecast areas are displaying sign of avalanche debris with few crown lines visible. This should highlight the reloading that has taken place with several avalanche cycles occurring yesterday. It should also be noted that we are seeing signs indicating the largest avalanches of the season took place yesterday. With Hillman’s having jumped the dogleg and Huntington gullies running into the trees, avalanche paths are fully developed and now contain significant amounts of snow.

WEATHER: The storm yesterday did not disappoint. Since Sunday morning, the Summit recorded just shy of 24” of snow with a SWE of 1.96”. Winds started from the S and then shifted to the ESE gusting to 60mph Sunday evening. On Monday, winds swung to the N and NW, gusting to 80mph midday before calming overnight to a current N 22mph. Today will be sunny and clear to start with clouds developing through the day. Wind speeds will remain low and shift to the W. Tonight, winds will increase to 40mph and shift to the S with a chance of up to 2” of snow late.

SNOWPACK: Prior to Sunday, our surface was a one-inch thick breakable crust from Wednesday as well as firm wind slab formed on Friday. An avalanche cycle on Friday ripped up the breakable crust in the Center Bowl, proving snow had the potential to step down below this crust layer. Snow over the past two days was relatively light density (~8%) and moved around by winds that changed direction and blew strong for periods of time, forming wind slab in most areas. There is clear evidence of scouring at high elevations in both Ravines. Huntington is showing more signs of wind-affected snow than Tuckerman with the Fan and the approaches to ice climbs having the most well-developed wind slab. In Tuckerman, more widespread smooth surface at mid-elevations along with a fresh crown in the Lip points to much more wind loading and wind slab that could be reactive.

 

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  8:30 a.m., Tuesday, February 14, 2017. A new advisory will be issued tomorrow.

Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2017-02-14

Avalanche Advisory for Monday, February 13, 2017

This advisory expires at Midnight.

Huntington Ravine will have EXTREME and HIGH avalanche danger today. North, Damnation, Yale, and Central will have EXTREME avalanche danger. Natural and human triggered avalanches are certain there. All other forecast areas have HIGH avalanche danger. Natural avalanches are likely and human-triggered avalanches are very likely.

Tuckerman Ravine will have EXTREME and HIGH avalanche danger today. Sluice, Lip, Center Bowl and Chute will have EXTREME avalanche danger. Natural and human triggered avalanches are certain there. All other forecast areas have HIGH avalanche danger. Natural avalanches are likely and human-triggered avalanches are very likely. The only exception to this rating is the Little Headwall which has Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible there.

Very dangerous avalanche conditions will exist today. Avoid all avalanche terrain later today as wind speeds begin to increase. Large avalanches in many areas will be likely.

AVALANCHE PROBLEM: This morning, there is Considerable danger of Storm Slab avalanches from 17” of new snow last night. Diminishing wind speeds at the start of the storm deposited this snow in our entire forecast area with little wind effect. Steep terrain this morning also has significant Loose Dry avalanche potential with Wind Slab concerns in upper start zones. As wind ramps up from the north, rapid loading of slopes with a southern through eastern aspect will occur and build large and dangerous wind slabs. These slabs will release naturally and most likely run far into flat areas like the floor of Tuckerman Ravine and the Fan in Huntington, as well as through avalanche paths in adjacent areas like the Gulf of Slides.

WEATHER: Summit wind speed is currently blowing near 40 mph from the northwest. Hourly forecast models indicate that winds will continue to increase through the day and shift to the north and northeast. The 17” (43cm) of new snow is light density (4% water) and will be easily transported by winds increasing to the 65-85 mph range from the north. Moisture in the lower atmosphere will continue to produce fog and upslope snow showers with another 2-4” of new snow falling through the day. Visibility will diminish through the day with ground blizzard conditions making navigation difficult.

SNOWPACK: Beneath all this new snow, you’ll find mostly firm snow with pockets of softer, newer snow along with a dense ice crust in steep terrain. Hard slab debris from a natural avalanche that occurred in the Lip on Wednesday contained a fair amount of this ice crust as well as the old sleet beneath. While it’s hard to say for sure whether today’s avalanche will step down into this layer, it doesn’t really make much difference in terms of the danger level. Today’s avalanches will likely shift from medium to large size as the day progresses and then to potentially much larger avalanches as slabs grow thicker. Crossing avalanche paths or entering Tuckerman or Huntington Ravine will put you in the crosshairs for multiple avalanche paths.

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  8:00 a.m., Monday, February 13, 2017. A new advisory will be issued tomorrow.

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

2017-02-13