Avalanche Advisory for Thursday 1-31-2013

Expires midnight 1-31-2013

Tuckerman and Huntington Ravines have HIGH avalanche danger.  Natural avalanches are likely and human triggered avalanches are very likely.  Travel in avalanche terrain is not recommended.

Ever feel like a yo-yo?  If you have felt that up and down sensation viciously repeating itself then you know how the mountain feels right now.  Last week -35F; yesterday and this morning 40’s and raining, and guess what….-15F  tomorrow!!  It’s kind of like an amusement park ride without the amusing part.  Rain, heavy at times, and fog are dominating the mountain this morning.  This coupled with the very high temperatures over the past 24 hours, pushing 50F at some elevations, are the bulls-eye avalanche data points driving the High danger rating today.  Melting around the clock and intense rain are weakening slabs rapidly.  Freewater has eroded bonds within previously cohesive slabs and is working its way down to weak layers of buried faceted crystals that developed during last week’s cold snap.  In addition to wet slab failure, we are also concerned about slush-water-snow blowouts in both Ravines.  When running water behind the snow and ice grows in mass to the point that subterranean channels can no longer handle the force and weight, hydraulic blowouts, which can be catastrophic, send an ugly slush debris flow downhill.  The main concerns for this hazard are near the Lip in Tuckerman and the narrowest gullies in Huntington such as Pinnacle and the junction of Diagonal and Yale.

Currently, it is raining hard and should continue to rain through the morning hours before the front rages through the mountains which will scale back moisture, increase winds, and send temperatures in a tumbling freefall.  Winds will increase blasting over 100mph in alpine zones and gusting to half that amount in the valleys.  Temperatures will drop like a rock, perhaps by 40F degrees by this evening.  This will do a couple of things.  It will begin locking up the existing wet snowpack from the surface down increasing its strength and stability and it will change rain back to snow producing up to 6” (15cm) by later tomorrow.  The transition from one weather scenario, 43F and pouring, to -15F and snowing, will make for some complex avalanche analysis.  As rain/freewater drain and freezing temperatures begin locking up the wet snowpack and increasing stability, new snow loading will be generate other problems.  Ultimately we will be decreasing one avalanche stability problem while increasing the other.  As new snow loads into strong lee pockets it may initially have poor or good adhesion depending on whether the first shot of snow falls on wet surfaces or frozen slick ones.  Either way, as snow builds up and insulates the old warmer snowpack you will likely see some decent bonding.  However, as pockets deepen this will become moot as fracture and new slab failure will likely occur within new snow above the interface with the old surface.

So… the main points for your safety.  1. We will have High avalanche danger this morning before decreasing somewhat this afternoon.  Be prepared for new avalanche concerns as snow loads in with the frontal passage later today and through the evening.  2. Expect VERY slick and hard conditions later today and through the weekend.  Expect to reach Mach1 in the event of a fall, with self-arresting to be unlikely.  Forecasted high winds may blow you off balance.  Crampons, ice ax and the experience to use them will be essential for safe travel.  3. As refreezing occurs, we will have a strong potential for ice damming on many climbs.  These dams of ice holding back running water can build up tremendous hydraulic pressure that can release with a tool placement or crampon penetration.  These are most common near bulges and have caused a number of accidents over the years.  4.  Backcountry skiing and riding will be extremely challenging.  Expect poor, icy, bumpy, core chattering, difficult conditions on the Sherburne ski trail 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 8:30a.m. 1-31-2013 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

2013-01-31 Print Version

Avalanche Advisory for Wednesday, 1-30-2013

Expires at Midnight 1-30-2013

Tuckerman Ravine will have CONSIDERABLE avalanche danger today.  Natural avalanches are possible and human triggered avalanches are likely.

Huntington Ravine will have MODERATE avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible.

Expect an increasing avalanche danger today.  Boy is there a lot to talk about today so let’s jump right in shall we.

WEATHER:  On the way up to Hermit Lake today I hit a wall of “hot” air at about 3000 ft that made me wonder if I had stumbled upon So.Cal’s Santa Anna breezes.  It cooled off a bit at 3800ft to 43F (6.2c) but climbing.  Avalanche terrain will see the mercury rise into the high 40’s, and perhaps beyond, as the brunt of precipitation bears down on the region.  What never ceases to amaze me is Washington’s swing in weather conditions.  When I left the mountain on Sunday the previous 11 days on the summit had an average low of -19.7 F (-29C) with the lowest point being -35F(-37C). Today the summit should hit the mid 40’s a swing of 80 degrees in a week!  Imagine it being 100 F at your house and a week later it’s 20.  The chance of rain will also increase through the day and will be likely this afternoon.  Valleys to the south of the Presidential Range are forecasted to receive 0.9 to 1.2” of rain while north a little more, between 1.0 and 1.45”, over the next 30 hours.  Most of this amount is expected overnight after dark.  Winds are also anticipated to ramp up as the front brings more precipitation gusting into the 90’s mph this afternoon and over 100 tonight.  As rain trails off the mercury is expected to collapse freefalling sending temperatures deep into freezing territory again tomorrow with snow!  I think I’m getting dizzy. More on that weather tomorrow.

AVALANCHES:  Warm temperatures are creeping their way into the snowpack, albeit slowly.  The snow was so cold from the past week it’s been a little slow to change not affecting stability quite as quickly as usual.   Take a look at a video we posted yesterday on our weekend update page with Jeff showing us some of the weak layer concerns.  Some locations have these issues a little deeper and others a bit closer to the surface, but the clip shows us some average depths.  My mind today is focused on what Jeff points out: slabs sitting on top of faceted crystals nearer to the surface and more developed facets, towards 2mm in size, a bit lower.

Slab strength will decrease through the day as warmth penetrates deeper into the slab, but as off 7am the T10 (snow temp 10 cm below the surface) temperature was still -3.6C at Hermit Lake.  This is quite a bit warmer than yesterday’s -8.2C however shows how slowly changes are occurring in the upper 4” of snow even with such warm air.  The game changer will be RAIN!  As rain moves in and takes hold of the mountains later today heat will be added to the snowpack rapidly.  Rain adds weight, brings freewater into the snowpack melting bonds that were adding strength, and may pool on more impermeable layers.  These all lean to an increased potential for natural avalanche activity.  Expect instability to rise through the day and tick up quickly when rain settles in.  Huntington is a rating lower than Tuckerman because the snowfields are much smaller which requires more instability to avalanche naturally and is also holding less pockets of snow due to intense scouring.  With this said both Ravines will be bumping the upper end of the Moderate and Considerable forecasts with the onset of consistent rain.  Peak instability will probably occur overnight as rain approaches 1.0” of accumulation.  As rain changes to snow we may have entirely new complications, but I’ll wait until tomorrow to get into that.

OTHER PROBLEMS:  1. Expect to need floatation getting off trail later today as post holing may become an issue. Ski’s, Splitboards, and snowshoes will be essential.  2. Climbers should expect the development of ice dams under hydraulic pressure beginning tomorrow.  3. We should begin seeing rapidly developing facets as cold air envelops the Ravines.  This should be most recognizable under new thin pockets of new snow that will deposit on the old surfaces that will be harboring wet snow at 0C.  We will be watching for this as a new weak layer.  4.  Hypothermia at 40F, rain and blowing near 100mph is pretty easy to get.  Think through above treeline travel today and certainly have the best in alpine clothing.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.Posted 8:40a.m. 1-30-2013. 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

2013-01-30 Print Version

Avalanche Advisory for Tuesday, 1-29-2013

Expires at 12:00 midnight 1-29-2013.

Tuckerman Ravine currently has Moderate and Low avalanche danger.  The Lip has Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The rest of the forecast areas in Tuckerman Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine currently has Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

Let’s cut to the chase today…snow stability during the daylight hours will be generally good, with some areas of concern. After dark, winds will begin to increase. This will cause the avalanche danger to begin rising, so if you’re out late today, expect avalanche danger to exceed the currently forecasted ratings.

Yesterday a light blanket of snow fell with rapidly diminishing wind speeds. This weather system left behind about 3-4″ of 6% density snow at elevations from Pinkham to Hermit Lake, while the summit is reporting 5.4″. Currently this snow isn’t doing anything to change the avalanche danger. It’s just sitting on top of whatever was there yesterday. Most of the prior snow surface was stable, wind-rippled, and fairly hard. Some locations had been scoured to expose an icy crust. Stability concerns could be found yesterday in strongly wind-protected areas such as the Lip and other isolated terrain features. These are the same places where we have concerns for the better part of today. If you are attracted to smooth and creamy features, be aware that the beauty may only be skin deep. Underneath you may find a temperamental snowpack waiting for just the right trigger to come along. Don’t be lured by superficial beauty; quality time can be spent in some of the less attractive areas and this is more likely to be a more stable relationship.

Moving into tonight, SW winds will begin to increase. The trend will continue through Wednesday with gusts reaching over 100mph (162kph). This will pick up snow from where it sits in the alpine zone, and load it into slabs on top of the existing light density blanket. It’s a pretty good set up for increasing avalanche danger, particularly on aspects facing to the north and east. The areas that will be slowest in developing stability problems will be the northern gullies of Huntington and Lobster Claw and Right Gully in Tuckerman. As if the snow and wind weren’t doing enough to create avalanche problems, tonight and tomorrow temperatures will steadily rise and we will be seeing some mixed precipitation and rain. The heaviest rainfall isn’t forecasted until Wednesday night, but even prior to this, the onset of sleet and rain will quickly exacerbate any of the newly developed avalanche problems.

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. January 29, 2013. 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

2013-01-29 Print friendly

Avalanche Advisory for Monday, January 28, 2013

Expires at Midnight 1-28-2013

Tuckerman Ravine has Moderate and Low avalanche danger.  The Lip has Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The rest of the forecast areas in Tuckerman Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine has Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

This morning, clear skies and pollution filtered sunlight created a dazzling alpenglow in the ravines.  The wind scouring is the predominant feature evident in the ravines today in spite of the 3/4” (2cm) of new snow that fell Saturday. Yesterday, wind speeds were ideal for loading the gullies with snow but the only snow available for transport was granular icy fragments not well suited to building cohesive slabs.  These crystals acted as abrasive particles to further sculpt the remaining snow into the chaotic jumble of firm, wind hammered waves of snow. There may be some pockets of unstable snow here and there. The Lip and the bowl beneath Sluice ice are areas where smoother snow that is not as wind hammered could be triggered by a climber or skier. Areas in Huntington where snow piled up on benches are also worth approaching with caution. Also, beware of incoming snow sometime this afternoon and evening which may create stability problems for anyone caught out during the evening or overnight.

So far in January, the summit has recorded just 29.4” (75cm) of snow. Compare this to the recent 30 year (1981-2010) average monthly total of 44” (112cm). In 1978, 94.6” (240cm) fell in January, but those were the good old days. In fact, the 30 year average from 1971-2000 was 52.8” (134cm). Our paltry snowfall this month suffered one thaw already and another is on the way on Wednesday. Hopefully, we won’t get much above freezing here.  If the 3-5” (12.5-17.5cm) due to fall this afternoon and evening comes in on the high side of the predicted amount, our terrain may look a lot more wintry than at present.  The northern Huntington Ravine gullies are currently thin ribbons of snow and ice with a lot of brush showing near the top outs.

The Sherburne trail is still hanging in there though the Little Headwall and creekbed leading up to it are basically unskiable which won’t likely improve enough with the incoming snow to changes things.

As mentioned over the past several days the old hard surfaces are still causing a traction problem in a number of locales. These old surfaces are camouflaged by newer snow in places and threaten skiers and climbers with long sliding falls.

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 8:30a.m. January 28, 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

2013-01-28 Print friendly

Avalanche Advisory for January 27, 2013

Expires at Midnight 1-27-2013

Tuckerman Ravine has Moderate and Low avalanche danger.  Center Headwall and the Lip have Moderate avalanche danger. Natural avalanches are unlikely but human triggered avalanches are possible. The rest of the forecast areas in Tuckerman Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

Huntington Ravine has Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

Unlike the calm start to yesterday, northwest winds in the 75-85 mph (120-135kph) range on the summit and a temperature 00F(-180C) at 3800ft are making the winter camping routine a bit more challenging for climbers staying overnight at the Harvard Cabin and Hermit Lake.  On the positive side, blowing slow and high winds will drop by 10-20 mph (16-32 kph) gradually through the day as temperature readings rise to 00 F (-180C) at the summit and 100 F(-120C) at 4,000 ft.  Snow stability will be similar to yesterday due to continued cold and in spite of some additional new as well as wind transported snow.  Small pockets of  slab, potentially reactive to human triggers,  were laid down again last night in some areas of Tuckerman Ravine; enough snow to almost cover the upper 8-10” (20-25 cm) of crown line which were showing beneath the ice yesterday afternoon.  Yesterday afternoon and into the night, the wind speed was just right for transporting what remains of available snow for transport out of Bigelow Lawn into those areas. Center Headwall and the Lip are rated Moderate not only because they have a greater potential to avalanche but also due to climbers difficulty in skirting the potential trigger points; recreationists might consider the many other routes available instead.  Although still rated at low, an example of other areas to carefully assess include the top right of Hillmans, the top of Left and above the narrows of Chute.

The wind speed and direction last night were also effective at continuing to scour the northern gullies in Huntington Ravine.  The top of Damnation has turf at the exit and Yale is showing more ice where easy snow ramps existed before.  The ice bulge in Central, which is often alpine ice of the softer variety, is now fresh water ice. These conditions should be factored into a climber’s time and terrain management plan before committing to a route.

Currently, full sun and clear skies are providing good visibility with some minor low level clouds which should clear through the day. Good visibility today will allow for navigation and the micro-level route finding necessary to avoid those isolated areas of wind loaded snow and bullet hard old surface on which self-arrest would be essentially impossible.  A few notable areas in Tuckerman to give a wide berth are the Lip and the expanse of snow below it, as well as the bowl-like feature beneath Sluice ice and above Lunch Rocks where the summer Tuckerman Ravine trail traverses left into the Lip.

As mentioned over the past couple of days the old hard surfaces are still causing a traction problem in a number of locales. These old surfaces are camouflaged by newer snow in places and threaten skiers and climbers with long sliding falls.

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 8:45a.m. 1-27-2013. 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

2013-01-27 Print friendly

Avalanche Advisory for Saturday, January 26, 2013

Expires at Midnight 1-26-2013

Tuckerman Ravine has Moderate and Low avalanche danger.  Sluice and the Lip have Moderate avalanche danger. Natural avalanches are unlikely but human triggered avalanches are possible. The rest of forecast areas in Tuckerman Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

Huntington Ravine has Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

Yesterday, fieldwork confirmed that Thursday’s wind in excess of 100 mph (160kph) scoured and wind packed most of our snowfields into a firm surface for cramponing.  Most areas are in the ankle deep range for boot penetration. It is the exceptions to this amount of boot penetration that are sources of concern for folks venturing into steeper terrain.  While our snow stability is generally good, cold temperatures and steep temperature gradients in the snowpack have not allowed the snow grains to bond well under the slabs particularly near rocks and beneath cliffs. Steeper sections of climbs are most likely to harbor pockets of unstable snow so avoid these sections, especially if you find you are moving into an area of deeper snow.  Areas listed as Moderate have the greatest potential to avalanche and due to the difficulty of skirting the potential trigger points; climbers might consider the many other routes available instead.

Right now at Hermit Lake, winds are dead calm and temperatures are a pleasant 00 F (-180 C). Full sun is providing excellent visibility.  These are the conditions where the movie soundtrack turns to ominous minor key strings as the diabolical villain is waiting in the wings to spring his trap.  In our case, the trap is falling temperature through the day and increasing wind speeds in the afternoon.  While not unusually cold, or windy, -10 F air on 55-75mph winds is enough to push a minor incident like a sprained ankle, forgotten headlamp or malfunctioning crampon into something more serious.  Don’t be the dummy in our film “Night of the Gnarly Ascent” that goes alone, unarmed, into the dark basement.

Still, today, like yesterday, is a decent climbing day with good visibility to allow for navigation and the micro-level route finding necessary to avoid those isolated areas of wind loaded snow and bullet hard old surface.  A few notable areas in Tuckerman to give a wide berth are the Lip and the expanse of snow below it, as well as the bowl-like feature beneath Sluice ice and above Lunch Rocks where the summer Tuckerman Ravine trail traverses left into the Lip.

As mentioned over the past couple of days the old hard surfaces are still causing a traction problem in a number of locales. These old surfaces are camouflaged by newer snow in places and threaten skiers and climbers with long sliding falls.

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 8:45a.m. 1-26-2013 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

2013-01-26 Print friendly

Avalanche Advisory for January 25, 2013

Expires at Midnight 1-25-2013

Tuckerman Ravine has Moderate and Low avalanche danger.  Sluice and the Lip have Moderate avalanche danger. Natural avalanches are unlikely but human triggered avalanches are possible. The rest of forecast areas in Tuckerman Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

Huntington Ravine has Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

The thermometer sits at 5F (-15C) at Hermit Lake right now making it feel downright balmy after the previous two days of arctic cold which, fortunately, were days off for me. Yesterday afternoon, heavyweight winds in excess of 100+ mph (160+ kph) battered our remaining snow like a mismatched bantamweight sparring partner leaving the poor snow whimpering in the corner.  Most gullies in Huntington are scoured down to the old icy surfaces. Some areas in Tuckerman Ravine have pockets of fresh, reactive windslabs but mostly contain larger areas of rippled, wind hammered drifts.  The hard surfaces remaining in both Ravines would allow for relatively easy crampon travel but a falling climber would accelerate quickly on the older, hard refrozen base layer of snow. Focused route finding would allow a hearty climber to skirt the pockets of drum-like hard slab over much softer sugary ice crystals created by our extreme temperature gradients of the last 48 hours. And I use the term “hearty climbers” since gusty winds blowing 55-75mph (90-120kph) with higher gusts and cold temperatures (high of 0F, -18C) on the summit will definitely keep the cold challenge and risk level in the exciting range. Climbers setting their sights on Huntington climbs should bring their “A” game when it comes to rope management and quick transition times at the belay.   

Still, today is a decent climbing day with good visibility to allow for navigation and the micro-level route finding necessary to avoid those isolated areas of wind loaded snow.  A few notable areas to give a wide berth are the Lip and the expanse of snow below it, as well as the bowl-like feature beneath Sluice ice and above Lunch Rocks where the summer Tuckerman Ravine trail traverses left into the Lip.  

As mentioned over the past couple of days the old hard surfaces are still causing a traction problem in a number of locales. These old surfaces are camouflaged by newer snow in places and threaten skiers and climbers with long sliding falls.   

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 8:45a.m. 1-25-2013 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

2013-01-25 Print friendly

Avalanche Advisory for Thursday 1-24-2013

Expires at Midnight 1-24-2013

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

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

A benefit of this arctic blast of cold air is when it finally gets tropical….say to about +10F… it will feel so pleasant I’ll want to wear a t-shirt. Until then this abominable devil is embedded in the White Mountains conspiring together to generate sub-zero air.  In addition to the mercury only climbing to -20F on the summits today the wind velocities will exceed 100mph (160kph) in the afternoon.  As yesterday, these arctic conditions will require a lot of experience and the best extreme weather clothing.  Even if you have these you still might be considered a little …well….’off’ to attempt a summit bid.  Seriously though, this weather is brutal and will take advantage of any mistake, so think through your actions today.

A little snow has been blowing around under clear skies this morning.  As winds pick up to the century mark later today more snow will be transported from above treeline into the Ravines.  Some areas may pick up a little and a number of areas may lose a little due to scouring. The 10” that fell over 4 days last week fell under temperatures in the teens and low twenties.  The snow that exists in alpine zones that survived some high winds after the snowfall has been subject to air 40-50 degrees cooler than when it fell. This temperature gradient has undoubtedly created some faceting and weakening of bonds particularly in the more porous pockets distributed in all the nooks and crannies above timberline.  The new snow crystals blowing around are very fine fragmented particles that are re-distributing into dense pockets in some isolated Ravine areas.  This is not an alarming issue right now, but it is my best take to explain the transport of new icy crystals under moderate Washington winds of 60mph.  It will be hard to say what 100+mph winds will do, but be prepared for newly transported icy crystals to be moved into avalanche terrain later today.  You may see some areas move to the upper end of their ratings if this occurs.  Besides this potential issue we continue to have intense spatial variability with a number of areas being subject to obvious scouring as noted by strong visual surface markings, the northern gullies in Huntington are one example.  Left over pockets of instability that haven’t changed much due to the cold air in place, most notably the Lip and it’s immediate neighbors in Tuckerman, are the locations that I am most concerned about.

As mentioned over the past couple of days the old hard surfaces are still causing a traction problem in a number of locales. These old surfaces are camouflaged by newer snow in places and threaten skiers and climbers with long sliding falls.

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 8:23a.m. 1-24-2013 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

Print Friendly 1-24-2013

Avalanche Advisory for Wednesday 1-23-2013

Expires at Midnight 1-23-2013

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

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

I can’t speak for you, but if I caught myself recreating above treeline today I think I’d borrow Joe’s straight jacket and commit myself.  It’s cold!  Although in principle we still have another 236 degrees C to go before getting to absolute zero on the Kelvin scale where particles theoretically stop, it’s frigid enough for me.  The summit is currently at -35F with winds gusting to 75-80mph.  I usually don’t like getting into windchill, but at around -90F that’s worth noting.  At Hermit Lake it’s about -19F which made doing the snowplot measurements for Joe a little rugged.  This weather is keeping most away from the mountain as it feels like a ghost town up here with just a few people scattered about.  Since I didn’t see you this morning you’re obviously pretty smart to wait for a more reasonable day.  It’s the kind of day where one minor issue can spiral into disaster, a.k.a.- “no mercy conditions”.

The mountain picked up just under an inch of snow yesterday and may get up to that much today.  I have a snow geek challenge today.  It’s a little cold for much snow to fall so if you are out and about anywhere and you see frozen particles floating down make a note of the crystal type and the associated air temperature and let us know what you saw.  We encountered a surprising amount of drifting on the trails this morning so I would expect we picked up a little bit more loading in some of our avalanche terrain overnight, albeit light.  Avalanche conditions shouldn’t change too much over the next couple of days. The cold air that moved in yesterday with the high pressure system will keep us very cold into the weekend. These temperatures slow snow sintering and stabilizing of weak slabs.  So expect the current instabilities that we have scattered in the two ravines to linger with little consolidation.

The focused instability concerns in Huntington Ravine can be found near the top and in the midsection choke points of South, Odell, Pinnacle and Central and to a lesser extent in mid-section chokepoints of Yale and Damnation.  Look for larger areas of unstable slabs to be found in Tuckerman’s Chute, Center Bowl, Lip and Sluice. I would consider these four Tuckerman forecast areas to be on the upper end of the Moderate rating definition, just coming down from yesterday’s Considerable.  Remember that although we use 5 different ratings to explain the avalanche likelihood and consequences snow doesn’t act in 5 specific ways so think of instability as a continuum on the spectrum between “Low” and “Extreme”.

In addition to extreme cold and avalanches think about the old hard surfaces that are still causing a traction problem in a number of locales. These old surfaces are camouflaged by newer snow in places and threaten skiers and climbers with long sliding falls.  Windblown snow is also hiding undermined areas of snow and ice from the recent thaw as well as newly formed ice so crampons will likely be needed sooner and on lower angled terrain than you might think.

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 8:28a.m. 1-23-2013 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

Print Version 1-23-2013

Avalanche Advisory for Tuesday, 1-22-2013

This advisory expires at 12:00 midnight, January 22, 2013

Tuckerman Ravine has Considerable and Moderate avalanche danger. The Sluice, Lip, Center Bowl, and Chute have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Right Gully, Left Gully, and Hillmans Highway have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Lobster Claw, the Lower Snowfields, and Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely.

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

Avalanche danger will be increasing through the day. Many areas currently have lower danger than forecasted but will increase in danger as the day wears on.

Yesterday, clear but cold and moderately windy conditions allowed us to travel safely into Tuckerman Ravine to assess our snowpack. What we found, coupled with new snow blown into the Ravines today, is the focus of avalanche concerns today. The windslabs we found yesterday were shearing cleanly and left a strong impression that steep terrain held slabs that would be sensitive to a human trigger. The paltry (1” or 2.5cm) snowfall last night from the low pressure system off the Maine coast was in the 5% density range and will exacerbate our instabilities as it builds into new slabs on slowly increasing winds. Starting at 8pm last night, summit winds out of the SW wrapped to the W and blew in the 15-20 mph (25-30kph) range. Winds are forecasted to gradually increase and shift to the NW this afternoon to 50mph (80kph) at sunset. The increasing wind speed will pack snow on top of the weak, lower density layer that was deposited through the night and morning hours. Expect to find unstable pockets of snow near the top and in the midsection choke points of South, Odell, Pinnacle and Central and to a lesser extent in mid-section chokepoints of Yale and Damnation. Look for larger areas of triggerable slabs, which may even slide naturally later in the day, in the Chute, Center Bowl, Lip and Sluice.

Smooth continuous bed surfaces, which have slowly increased in size since our recent January thaw, exist in some areas of the ravines. Lots of melting, particularly in our south facing terrain, decimated our snowpack and created the hard icy surfaces scattered around in wind scoured locations. These old surface are camouflaged by newer snow and makes worse another hazard that frequently threatens skiers and climbers…the long, sliding fall. Wind deposited snow often forms lens shaped pockets of snow that are thin at the edges. While you may be able to boot up the thicker, center of these pockets with plenty of boot penetration, you’ll find the edges of the slabs may break out from under foot, or ski, sending you skidding down the slope. Remember that these thinner edges can also serve as the weak spot and point at which cracks develop and sometimes propagate into the rest of the slab. Windblown snow is also hiding undermined areas of snow and ice from the recent thaw as well as newly formed ice so crampons will likely be needed sooner and on lower angled terrain than you might think.

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 9:00am, January 22, 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

Printer friendly 2013-01-22