Avalanche Advisory for December 22, 2013

Based on the anticipated power outages due to the ice storm, MWAC is posting this forecast Saturday afternoon for Sunday based on early weather forecasts and good model confidence.  

Tuckerman and Huntington Ravines have CONSIDERABLE avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely.  Dangerous avalanche conditions exist requiring careful snowpack evaluation. Cautious route-finding and conservative decision making is essential.

 AVALANCHE PROBLEM:  Wet Slab issues will continue to be a problem today as rain and/or freezing rain adds weight and melts bonds creating additional percolating free-water.  This water moving through the snow can reach and lubricate impermeable or semi-permeable lens of ice or crust.  Wet Slab failure can occur due to a mix of factors and usually are naturally triggered making travel in avalanche run out paths unwise.  Due to their typical high mass they have the ability to run full path distances and beyond. This avalanche problem will be less severe if precipitation falls as freezing rain or some other frozen form.

WEATHER:  Expect many changes in weather today.  You will likely encounter rain, freezing rain, mixed precipitation and even a little snow many times through the day.  As the temperature flirts with the freezing mark be prepared for it all.  New  ice accumulation over an inch is possible. Fog will complicate matters by reducing visibility for navigation as well as for assessment of hazards above.

SNOWPACK: Rain mixing with freezing rain on snow creates our primary potential hazard today. This could create widespread instability on steep slopes in both ravines. Snow fields exist in many areas which either did not slide earlier in the week or slid and then reloaded during periods of upslope snowfall. The potential also exists for areas of deeper slabs to release due to the increased water weight stressing the slab as well as the relative heat of the rain melting bonds that have the held the slab in place. The timing of this weakening process will vary according to the depth of the slab and in many lee areas, predominately easterly facing, these slabs could be several feet thick if not thicker. Deeper slabs beneath steep ice as well as snowfields resting on benches will also be activated by the increased load, heat and lubrication process. Even small amounts of rain falling on areas of ice will lubricate bed surfaces and further increase the trend of instability.

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 3:00 p.m. Saturday, December 21, 2013. A new advisory will be issued tomorrow.

Frank Carus/Chris Joosen, Snow Rangers
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2013-12-22 Printer friendly

 

Avalanche Advisory for Saturday, 12-21-2013

Expires at Midnight Saturday 12-21-2013

Tuckerman and Huntington Ravines have CONSIDERABLE avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely.  Dangerous avalanche conditions exist requiring careful snowpack evaluation. Cautious route-finding and conservative decision making is essential.

 AVALANCHE PROBLEM: Today’s avalanche problem has transitioned to Wet Slabs from Thursday and Friday’s focus on Wind Slab.  Higher than predicted water amounts yesterday gave the existing snowpack a quick head start towards becoming a Wet Slab problem.  Today additional rain mixed with freezing rain will percolate into left over deeper dry snow creating Wet Slabs as the widespread problem.  Wet Slab issues will become an increasing problem today as rain adds weight and melts bonds creating additional percolating free-water.  This water movement generates flow finger highways for water to reach and lubricate an impermeable or semi-permeable lens.  Wet Slab failure can occur due to a mix of  factors and usually are naturally triggered making travel in avalanche run out paths unwise.  Due to their typical high mass they have the ability to run full path distances and beyond.  

WEATHER: Temperatures will move above the freezing point today with freezing rain early then rain in the afternoon.  High temperatures will push to 40 degrees F above 4,000′ in the early afternoon. Low visibility due to fog will impair visual assessment of hazards above and make navigation challenging as well as reducing any chance of empl0ying the “point last seen” strategy during an avalanche self-rescue event. Expected precipitation is around .5″ during our forecast period with .2″ falling during the daylight hours.

SNOWPACK: Rain on snow creates our primary hazard today. Rain falling on snow will create widespread instability on steep slopes in both ravines. Snow fields exist in many areas which either did not slide earlier in the week or slid and then reloaded during periods of upslope snowfall. The potential also exists for areas of deeper slabs to release due to the increased water weight stressing the slab as well as the relative heat of the rain melting bonds that have the held the slab in place. The timing of this weakening process will vary according to the depth of the slab and in many lee areas, predominately easterly facing, these slabs could be several feet thick if not thicker. Deeper slabs beneath steep ice and snowfields as well as resting on benches will also be activated by the increased load, heat and lubrication process. Even small amounts of rain falling on areas of ice will lubricate bed surfaces and further increase the trend of instability.

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 0800a.m. Saturday, December 21th, 2013 . A new advisory will be issued tomorrow.

Christopher Joosen/Frank Carus, Snow Rangers
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2013-12-21 Print friendly

Avalanche Advisory for Friday December 20th, 2013

Expires at Midnight Friday 12-20-2013

Tuckerman Ravine has Considerable, Moderate and Low avalanche danger. The Lip, Center Bowl, and Chute have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Sluice and Left Gully have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.  All other areas have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

Huntington Ravine has Considerable, Moderate and Low avalanche danger. Central and Odell gullies have Considerable avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely. Pinnacle and South gullies have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.  All other areas have Low avalanche danger.  Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEM:  Wind Slab in easterly and southeasterly start zones was created during the last 48 hours and will continue to grow with today’s forecasted snow. As temperatures continue to climb, this wind slab may become unstable pushing us solidly into our forecasted danger ratings for the day. Warm temperatures and potentially even some rain on the snow pack will weaken bonds especially where the Wind Slab is thinnest. Thin spots in a slab tend to be trigger points for adjacent thicker, stronger slabs which currently have grown largest on benches and discontinuous slopes in the Lip and Center Bowl area of Tuckerman and in Huntington’s Central and Odell Gully.  Be wary of any larger snowfield if precipitation rates increase or the warming trend occurs during the forecast period ending at midnight.

WEATHER: A very complex set of systems will be moving through the region over the next 72 hours having the potential to play out in a number of ways depending on the exact track and temperatures.  Today, light precipitation is expected to start as snow and potentially change to mixed conditions, hedging towards a possibility of brief rain in the afternoon.  Water equivalents (QPF) is looking to stay within 0.1” (2.5mm).  This could produce an inch of snow before moving to mixed and liquid precipitation at the 5000ft level.  Winds are expected to be from the W at 35-50mph (56-80kph) and then climbing to 50-70 mph (80-112kph) with higher gusts.  Over the weekend a storm will bring significant freezing rain (ZR) to the region and perhaps deep snow to areas north of the Presidentials.  QPF is expected between 1.2” and 1.75” (3-4.5cm) of water for Saturday through Monday morning.  The NWS has issued a WINTER STORM WATCH for 48 hours beginning Saturday at 7am.  More on this in the Weekend Update late this afternoon.

SNOWPACK: As referred to yesterday we have been getting many shots of low precipitation amounts recently.  Coupled with high winds, this has given us a substantial amount of spatial variability around both ravines.  Expect to find very different snowpack stratigraphy as you move around with different stability test results.  Today we are starting with forecast areas at the low end of their ratings.  This will climb through the spectrum of their forecast towards the upper end if we do receive a bit of rain late in the day.  As an example “the Lip” will begin at the very low end of Considerable and climb ending solidly in the middle or upper end of Considerable as we transition to liquid precipitation.  Extrapolate this concept for all forecasted ratings and locations.  In areas posted at Low small bed surfaces exist.  Stay attentive to how pockets, albeit small in size, may react to light rain.  If we do receive any more than a brief shot of scant rainfall amounts expect these locations to bump up a rating.  This is not expected to occur, but important to remember.  Expect and elevated avalanche danger through the weekend due to the incoming storm.

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 0810a.m. Friday, December 20th, 2013 . A new advisory will be issued tomorrow.

Christopher Joosen/Frank Carus, Snow Rangers
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2013-12-20 Print

Lost hiker on Lion Head

A hiker descending off the summit of Mt. Washington became lost after dark without a headlamp. He sent numerous texts to his friend who, having turned back earlier, was waiting at Pinkham Notch. The last of these messages indicated he needed rescue assistance immediately. These messages were not received until the friend had traveled back to town where cell service is more reliable. It was this string of messages that instigated the rescue effort. Teams from the USFS and Mountain Rescue Service located the hiker near treeline on the Lion Head Trail. He was uninjured and was able to walk down to Hermit Lake; from here he was transported by snowmobile to Pinkham Notch.

Avalanche Advisory for Thursday, December 19, 2013

Expires at 12:00 Midnight, Thursday, December 19, 2013

Tuckerman Ravine has Considerable, Moderate and Low avalanche danger. The Lip, Center Bowl, and Chute have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Sluice, Left Gully, and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecasted areas have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

Huntington Ravine has Considerable, Moderate and Low avalanche danger. Central and Odell gullies have Considerable avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely. Pinnacle and South gullies have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. In all other forecasted areas, natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEM:  Wind Slab is the main avalanche problem today. West winds yesterday blew consistently at an ideal loading speed. The summit recorded around 3.5” (9cm) of new snow in the last 3 days which provided all the snow necessary to build potentially dangerous slabs in lee areas and gullies with an easterly and southeasterly aspect. Winds ramped up yesterday and moved the snow into these easterly start zones. Areas such as the Lip, Center Bowl and Chute may possibly slide naturally today as forecasted winds and more light snowfall continue the loading process. Persistent slabs created during and immediately after last weekend’s 14” snowfall that survived the avalanche cycle on Monday have had little chance to stabilize due to cold weather so they may contribute to the windslab instability problems.

WEATHER: The mountain has received snow 25 out of the past 28 days.  Since the big winds on Monday afternoon we have picked up 3.5” (9cm) of new snow.  Moderate winds on Tuesday and Wednesday morning allowed for some snow movement until about noon yesterday.  Winds ramped up gusting to about 70mph (112kph) in the midafternoon flipping a switch on the mountain engulfing it in blowing snow and clouds.  Loading winds from the west today will continue to be high gusting over 80mph (128kph) through the afternoon before subsiding overnight.  Up to another 2” (5cm) of snow is possible through the day and another 1-3” (2.5-7.5cm) tonight before a potentially ugly freezing precipitation event comes in for the weekend.

SNOWPACK:  High winds from yesterday afternoon and overnight peaking at 87mph this morning moved available snow from alpine zones that fell since Monday.  New wind slabs over the past 18 hours have developed predominately on E and SE aspects due to W and WNW winds.  The bullseye locations of concern in Tuckerman are the terrain features with the strongest lee of these winds, namely the Lip through the Chute posted at Considerable today.  Expect to find a mix of slab hardness across these areas depending how sheltered they were from winds.  It is quite likely that new wind slabs will become softer and weaker the higher you are.  The main slabs that concern us are from the Lip down under the Headwall ice.  The adjacent gullies, the Sluice and Left gully, follow behind as the next locales to use caution.  We would consider them on the upper end of the Moderate definition hedging towards Considerable depending on snowfall totals today.  In Huntington the ratings are a bit less consistent. Central and Odell are the dominate issues due to their aspect and developed bed surfaces.  Staggered between is South and Pinnacle which have lower stability issues but should see building issues today, although staying within the Moderate rating.  All of the aforementioned gullies and snowfields will see increasing instability today and tonight.  We will get into the sleet and freezing rain event for the late Friday and the weekend tomorrow.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.Posted 8:20a.m. 12-19-2013. A new advisory will be issued tomorrow.

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

2013-12-19 Print

Avalanche Advisory for Wednesday, 12-18-2013

Expire Wednesday at midnight 12-18-2013

Tuckerman Ravine has Moderate and Low avalanche danger. The Sluice, Lip, Bowl, Chute and Left Gully have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other areas have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

Huntington Ravine has Moderate and Low avalanche danger. Central and Odell gullies have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible. In all other areas, natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEM: The problem is predominantly Wind Slab due to storm snow loaded by the subsequent strong winds from the alpine zone and yesterday’s light afternoon accumulation. There was a lot of avalanche activity that occurred sometime on Monday.  This was verified in Tuckerman’s Lip, above the main Headwall, the Chute, Left Gully, and Hillman’s Highway.  In Huntington, avalanche crowns or debris were seen in Central, Odell and South.  Some of the areas of hang fire and areas that didn’t avalanche I would probably start calling Persistent Slabs as they transition from being Storm Slabs. Cold temperatures and a clear Monday night have led to little settling or consolidation of these leftover slabs and it’s possible that some early faceting may be recognizable by today. Diminishing winds and a scant 1.25” (3cm) of 5% snow from yesterday shouldn’t change things too much from Tuesday’s forecast however additional snow showers are expected this afternoon likely adding to today’s general Wind Slab problem. This has bumped Left and Odell from Low to Moderate today. Based on the cold low density snow we have been having lately wherever you find relatively soft snow in steep terrain, you should be concerned about triggering an avalanche requiring cautious travel.

WEATHER: Light snow that fell yesterday afternoon into the evening came on a SW and WSW wind from 35-50mph (56-80kph) with several higher gusts.  Since midnight these winds have settled in from the W and slowed significantly.  Currently velocities are in the low teens mph, but will ramp up quickly into the afternoon and shift once again.  Winds may hit a hurricane force (77 mph) from the NW late today before shifting back to the W and gaining strength into Thursday, perhaps gusting to 90mph (144kph).  Along with the afternoon shift today we can expect more snow showers with some measurable accumulations, but they should stay light.

SNOWPACK: Winds today, perhaps reaching over 70mph (112kph), will transport the 1+” (3cm)from yesterday and any new snow we may see today.  But is very unlikely to move much snow from the weekend storm that the gusts, reaching 108mph (173kph), couldn’t do on Monday.  Although new wind slab that developed after dark last night, and may develop this afternoon, shouldn’t be substantial you would be smart to expect some thin new wind slabs.  I bumped Odell and Left gully to Moderate based on the potential of where they may be at later today. Although still at Low, climbers should pay attention to the approach snowfield under Pinnacle in Huntington.  Low density snow sluffing off the ice may have built new wind slab concerns in this pocket. Approach climbs with caution; it’s not uncommon to for people to trigger avalanches on the slope leading up to intended climbs.  Other areas posted at Moderate yesterday and today may drift to the upper end of the rating definition based on the amount of snow we see this afternoon.  Anticipate some of these areas facing the E and SE, such the Tuckerman Center Bowl and Lip, to be riding the fence between Moderate and Considerable.

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 833a.m. 12-18-2013. 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

2013-12-18 Print

Avalanche Advisory for Tuesday 12-17-2013

Technical difficulties today. Please click the .pdf link below for today’s advisory.

2013-12-17

Avalanche Advisory for Monday 12-16-2013

Expires at 12:00 midnight Monday 12/16/2013

Tuckerman Ravine has Considerable, Moderate and Low avalanche danger. Sluice, Lip, Center Bowl, Chute and Left Gully have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely in these areas. Hillman’s Highway has Moderate avalanche danger. Evaluate snow and terrain carefully in Hillman’s. Lobster Claw, Right Gully, Lower Snowfields and Little Headwall have Low avalanche danger due to limited snowcover. Continued wind loading will increase the likelihood of avalanches today.

Huntington Ravine has Considerable, Moderate and Low avalanche danger. Damnation, Yale, Central, and Pinnacle Gullies have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely in these Considerable rated areas. North and Odell have Moderate avalanche danger. Heightened avalanche conditions exist on specific terrain features. South Gully and Escape Hatch have Low avalanche danger. Continued wind loading will increase the likelihood of avalanches today.

AVALANCHE PROBLEM: Moderate to intense wind transport of yesterday’s 14” of light density snow will continue today. Windslab will continue to develop on our thin snowpack which consists of relatively weak, cold snow with areas of older, harder raincrust. Bed surfaces are limited in size in the lower rated areas and largest in the Considerable rated areas. Pockets of new snow also exist in locations sheltered from southerly winds during the December 14-15 snow event which could produce soft slab avalanches.

WEATHER: West winds blowing 60-80 mph will shift to the northwest and decrease slightly to 50-70 mph. These windspeeds will be very effective at picking up and moving snow into avalanche start zones on slopes and gullies with east and southeast facing components. Falling temperatures will slow the sintering and stabilizing process. Radar indicates continued snow squall activity as lingering moisture produces upslope snowfall. This new snow will contribute to windslab development and reduced visibility.

SNOWPACK: Easy and clean shears in new snow layers were observed in sheltered locations yesterday due to density/crystal form changes during the 14” snow event. This new snow is currently blowing into east and southeast facing forecast areas and forms the primary stability concern. Prior to the new snow, early faceting occurred in many areas. Though these facets probably will not be the weakest layer they may contribute to a weakening of overlying windslabs or sluff piles such as can be found at the bottom of the first pitch of Pinnacle and beneath the main ice bulge in Central Gully. As is typical of our region and forecast area, spatial variability makes continuous assessment and reassessment of both the snowpack you are on and the snow you are moving into a necessity. Though our snowpack is patchy and discontinuous in nature, it is more than capable of generating avalanches of a size capable of carrying a person into rocks and over ice cliffs. Exposed terrain continues to supply terrain traps capable of catching avalanche debris to a depth capable of burying a person. Reduced visibility due to blowing snow will make visual assessment of snow and terrain challenging.

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 0900 Monday 12-16-2013  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

2013-12-16

Avalanche Advisory for Sunday 12-15-2013

Expires at Midnight Sunday 12/15/2013

This is the initial 5-scale avalanche danger rating forecast for the season.  You will now see daily advisories.  Tuckerman and Huntington Ravines have CONSIDERABLE avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely.  Dangerous avalanche conditions exist.  Careful snowpack evaluation, cautious route finding and conservative decision making is essential.

AVALANCHE PROBLEM– We have been watching the development of bed surfaces in our avalanche terrain carefully over the past several weeks.  They have been in a slow constant growth mode and have seen snow 13 out of the past 15 days.  In our forecaster’s discussion this morning we felt this storm is clearly sending us over to having more concern for natural avalanche activity.  The avalanche problems today are a combination of Storm Slabs and Wind Slabs.  It is plausible we may see a number of small natural avalanches today due to the low density touchy soft slabs that will develop all day and into tomorrow.  The largest of these would occur in places that have the most sizeable bed surfaces, namely Left Gully and the Chute in Tuckerman and Central Gully in Huntington.

WEATHER— A WINTER STORM WARNING is in effect until noon today.  Snow began last night and picked up in intensity early this morning with periods likely at the S-3 rate.  As of 630 there is about 10+ inches (25cm) on the mountain with more coming.  As snow dissipates in the valleys upslope showers will continue for the higher terrain giving us an additional 1-3” (2.5-7.5cm) tonight and a bit more into the early Monday morning.  Clearly we will be at 12”+ (30cm) by the time precipitation wraps up.  Winds will be from the SE up to 75mph (120kph) moving to the W later today and diminishing to perhaps as low as 30 mph (48kph)

SNOWPACK— The snowpack preceding this event has be quite variable depending on location put a consistent theme has been many layers due to our nickel and diming snowfalls.  Some of these have started to move to early facets due to our cold conditions lately.  Today’s cold, low density, storm and wind slabs will load early on N and NW facing aspects predominately due to SE winds.  Expect some crossloading and anticipate our larger dominate bed surfaces facing E to receive more loading late in the day as winds shift to the W.  Strong overnight winds causing additional loading and temperatures dropping to about -15F will keep new slabs unstable.

This event should kick our day to day avalanche concerns up a notch as it will undoubtedly add substantially to snowfield sizes.  With this said as conditions clear up in the next 24-48 hours we expect to also see areas that were quite meager a few days ago to still be that way.  So although today we have a blanket Considerable forecast you will likely see us not forecast for some areas by middle of the week. Stay tuned.

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 0815 Sunday 12-15-2013  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

12-15-2013 Print Version

Avalanche Advisory for Friday, December 13, 2013

A new advisory will be issued when conditions warrant or within 72 hours
Unless updated this advisory expires at 12:00 midnight Sunday, December 15, 2013

This is an early season GENERAL AVALANCHE ADVISORY for Tuckerman and Huntington Ravines. General Advisories are issued when isolated instabilities exist within the forecast areas. Forecasts using the 5-scale danger rating system will begin when snowfields and bed surfaces become more developed. Please remember that avalanche activity may occur before the issuance of a 5-scale danger rating forecast. As always, you will need to make your own snow stability assessments when traveling in avalanche terrain.

There are isolated snowfields in Tuckerman and Huntington Ravines that are growing in size and may harbor instabilities. Spatial variability is strong in these early season conditions. Climbers can expect to find potentially unstable slabs on benches beneath steep sections of rock and ice and in lee areas. The largest of these areas can currently be found in Sluice, Lip, Center Bowl, the Chute and Left Gully areas of Tuckerman and Central and Odell Gullies in Huntington. Other smaller snowfields are building in Pinnacle and possibly Yale. Increasing winds following Wednesday’s snowfall created pockets of windslab in both Ravines. Due to the “upside down” nature, that is dense slabs over lighter ones in the upper snow pack, these slabs may be reactive, even touchy, to human triggering. Add to this problem  2-4” of very light density snow falling and blowing Friday and cold temperatures slowing any natural stabilizing processes Friday night and Saturday. Additionally, 12” inches more snow predicted for Saturday night and Sunday will add to our stability issues and make a very challenging weekend to climb safely.  More reactive and much larger slabs in the Ravines on Sunday may even avalanche naturally without a human trigger.

Approximately 4-6” of new light density snow fell Wednesday on light winds. This snow did not bond well to cold, hard water ice or the ground, grass or rocks. New snow today (Friday) is already falling and is expected to continue at the rate of S-1 snow shower activity yielding 2-4”. West and northwest winds will blow at an effective loading velocity and will create windslabs on our existing thin snowpack. The good news is the snowfields are small in size due to meager snowfall so far this season. The bad news is the snowpack is so meager that numerous rocks and ice cliffs remain exposed making even a small slide potentially disastrous. Terrain traps are numerous and deep making burial a real possibility, even from smaller avalanches.

Today, temperatures on the summit are forecast to fall to -20F and rise to the mid-teens below zero tonight with winds in the “really cold” wind chill range. Check the weather forecast carefully as the next 48 hour period will change rapidly and frequently with passing weather systems. Trail conditions are challenging due to water ice, rocks and holes concealed by light density snow. Microspikes and crampons are necessary for most, if not all, trails. Saturday night’s storm may bring joy to Sherburne skiers although hidden hazards exist in the thin snowpack.

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 9:05 a.m., Friday, December 13, 2013. A new advisory will be issued when conditions warrant.

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

2013-12-13 Print Friendly