This advisory expires at Midnight Friday 2-03-2012

Tuckerman Ravine has MODERATE and LOW avalanche danger.  The Right Gully, Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible.  Left Gully and Hillman’s Highway have Low avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features, which do exist.  The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when warranted.

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

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

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

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

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

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

2012-02-03 Print friendly

Well it’s another Friday, and time for a Weekend Update. From what we hear, there will be another six weeks of winter. You may be asking “another? Where were the first six weeks?” The past month, old George has been feeling more winter-like. It’s been a reasonably snowy January, with the summit recording just a hair under 39″ of snow for the month. That’s about what we received in December, but double what fell in November. The biggest downside I can see to winter this year has been the number of warm days. In December and January, there have been ten days the summit temperatures have gone above the freezing mark. The current deficit is a tough one to grow our way out of, so let’s hope for above average snowfalls for the next six (or ten) weeks and an end to the warm days.

Weather for the weekend is looking pretty nice overall. At least in the valleys, you should expect sunny skies and temperatures just below the freezing mark. This is nearly perfect weather for the Mt. Washington Valley Ice Fest, taking place this weekend at all the local crags around the valley as well as on Mt. Washington. Despite the beautiful valley weather, the mountain has it’s own attitude, and can sometimes put on a mean snarl when all around it is full of smiles and fun. That was the case today, as blowing snow and cold temperatures were the conditions of the day.

Joe and I took a walk up Hillman’s Highway to check for any pockets of unstable snow. After surmounting the wet debris pile from Wednesday, we found a smooth surface appearance. The top couple inches was a crusty layer of graupel held together with some unseen force, and beneath this was a deep pool of graupel sitting above a crust layer. I didn’t realize it at the time, but we would revist that graupel layer a few other times throughout the day. We continued up into Hillman’s, taking on everything the mountain could throw at us this day, mostly wind, cold, and gusts full of airborne snow. As we fought our way through the sandblaster of snow and spindrift, little did we know it was a gorgeous day down in the valley. Near the top, we reached a completely wind-affected start zone, with very strong sastrugi allowing little boot penetration. Stability here was very good. Realizing there was little to be learned by continuing to the actual ridge, we retreated back to Hermit Lake.

Overall, Hillman’s has good strength in the new windblown snow. The graupel layer is certainly present in many locations, and there are some pockets that have a snappy slab on top of the graupel. These are easy enough to avoid if one is a savvy traveler in avalanche terrain. Most of the new windblown slab we found in Hillman’s is fairly brittle, there is not a lot of propagation potential to it, but it does have some. In talking this over with Chris, he pulled out a lesson he learned in National Avalanche School way back in his early days. It was that a tumbling skier can put as much impact on a slope as a typical hand charge explosive. This is worth remembering, since you might be lulled into thinking there is no chance, when in fact all you have to do is have a strong enough impact. I think the term “unlikely” is appropriate for describing the potential for human triggered avalanches here.

In case we hadn’t suffered enough by climbing Hillman’s today, we decided to head over to Huntington in hopes of gathering information that could allow us to lower the avalanche hazard there in a couple areas. Instead of this, we found information leading us to think the most likely thing to do is cover all of Huntington with a Moderate rating tomorrow (South and North were rated Low on Friday). When we were there in the morning, it was clear and not blowing much at all except for a couple plumes in Central and Odell. We were able to see into all the gullies, and poked into the snow down below Odell. Coming back in the afternoon was a different story. We couldn’t clearly see much. There was so much blowing snow in the air that it may well have just been in the clouds. The positive side of this is that the snow wasn’t really landing and building energetic and reactive slabs. Rather, it was sluffing off in many areas and piling up into slabs with low cohesiveness and low propagation potential. Again the graupel layer showed it’s face as we climbed up toward Pinnacle. This is a very weak layer, where the danger coming in is very dependent on what is above it. In some areas this is the snappy slab, and in other areas it’s just a pile of sluffed-off snow that would take explosives (or a heavy human impact like a falling climber or skier) to trigger it. For Huntington as a whole, I believe we are at the lower end of the Moderate rating in most areas. The stronger lee areas are the ones you’ll want to avoid, as are any area where the upper layer is able to propagate above the graupel. The key piece of information for me when I think about what we saw there is the quantity of blowing snow. Even if stability is generally good, the loading that was going on was impressive. Avalanches happen when the stress on the snowpack overcomes its strength, so a heavy load like what was applied today should raise some red flags in your head.

Tonight there is a slight chance for additional snowfall. I doubt this will amount to much, but if it does, don’t hold me at my word for anything I’ve said above. Do your part by checking the morning’s avalanche advisory before you decide to head out into the ravines. Or if you’re an early go-getter, check in with us in the morning on the mountain. Hopefully tomorrow we’ll get some new photos posted from today’s adventures. For now though, I’m calling it a day. See you on the mountain,

Jeff