Jeff

USFS Snow Ranger since 2005.

Feb 252015
 

This advisory expires tonight at 12:00 midnight.

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

All forecast areas of Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely. Be aware of the potential for ice dams today.

AVALANCHE PROBLEM: Similar to yesterday, wind slab is the primary threat today. The focus of attention is in the middle of Tuckerman, in the Sluice, Lip, Center Bowl, and Chute. Other areas of Tuckerman, such as Right Gully and all areas rated at Low, have better stability overall and more options for avoiding unstable snow. There is a chance for new snow today. If we should receive a couple inches, expect avalanche danger to push the limits of their forecasted ratings due to new wind slab creating instabilities and increasing the load on existing instabilities.

WEATHER: In a season marked by many extreme weather events, today seems rather ho-hum. Overcast, fog, and some light snowfalls may obscure visibility. The Observatory is forecasting a trace to 2” (5cm) of snow, and if it continues for a while at the rate at which it’s currently falling, we just might see the full 2”. Winds will be from the W and increasing in speed today, reaching 45-60mph (72-97kph) with higher gusts by the afternoon.

SNOWPACK: Currently it is snowing at Hermit Lake. This makes me think about the potential for new slab to be developing with an increasing W wind. There probably won’t be a lot of snow for the winds to work with, but pay close attention to accumulations and be thinking of increasing avalanche danger if we get 1-2” (2.5-5cm) of new snow. It doesn’t take a lot of new snow to build slabs deep enough to be a problem when the winds are as forecast today.

A good benchmark for the snowpack is Monday, February 16th. Winds this day raged harder than they had in several years. This left a very firm slab in the Center Bowl and Lip. The Sluice had very hard slab as well, but some was avalanched down into the floor. Since the 16th, we’ve had a couple good snowfalls along with winds ranging from the SW to the NW and another avalanche in the Chute. These conditions have created a very variable and layered snowpack in the middle of Tuckerman, which is the primary concern today especially for the potential for a person to trigger something here. I also can’t ignore the possibility of an avalanche stepping down into the hard slab layer from the 16th and producing a large and damaging avalanche.

Areas rated Low in Huntington don’t have much for previously existing stability problems. They were scoured clean by strong winds Monday gusting almost to 100mph (162kph). The same can be said for Left Gully and Hillman’s. Right and Lobster Claw have a lot of firm stable snow and some sections of wind loading, so use your safe travel and snowpack assessment skills to help you avoid instabilities in these areas. Any unstable snow in the Lower Snowfields and Little Headwall will be confined to isolated terrain features, so if you go looking for the largest areas of snow here, don’t be surprised to find some avalanche potential.

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 8:15a.m. February 25, 2015. A new advisory will be issued tomorrow.

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

2015-02-25

 Posted by at 8:14 am
Feb 242015
 

This advisory expires tonight at 12:00 midnight.

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

All forecast areas of Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely. Be aware of the potential for ice dams today.

AVALANCHE PROBLEM: Avalanche problems in our forecast zones today are largely confined to Tuckerman with very few potential problems in Huntington. Wind slab is the primary threat. Recent wind-loading has triggered natural avalanches on some slopes, which is considered “bulls-eye” information pointing toward instability. The Sluice, Lip, Center Bowl, and Chute in Tuckerman are the areas with the greatest potential for avalanches. We are beginning to see and hear of avalanches and/or unstable snow conditions outside of our forecast areas, so pay attention whenever you are near potential avalanche terrain.

WEATHER: In the last 7 days, the summit has recorded 16.5” of new snow (42cm). More than this has been recorded at our manual snow plot at Hermit Lake. Yesterday, strong NW winds blew at an average speed of 71mph (114kph) with a peak gust of 98mph (155kph). Today, wind speeds will be much more manageable, decreasing through the morning but increasing again in the afternoon. Temperatures will remain very cold; in the ravines you can expect temperatures hovering around 0F (-18C).

SNOWPACK: A quick visual scan of Tuckerman this morning gave me goosebumps. It’s amazing how quickly the Sluice, Lip, and Center Bowl have grown to a size that should make anyone stop and stare for a moment or two. There is currently a lot of snow loaded into these slopes and it has not been shedding it off regularly in avalanches as it often does. The net effect is a deeply layered snowpack capable of producing a very large avalanche. The snow on these slopes is also well-connected from one path to another, which allows a single fracture to propagate across multiple avalanche paths. You might be wondering about the stability of the snow here. Well, so am I. We tend toward conservative decision making, especially when consequences are high, so you won’t find me center-punching a bootpack up the Lip or headwall today. Although I don’t have hands-on information to give, I have a lot of confidence in the potential for a person traveling through here to trigger an avalanche.

Right and Lobster Claw have a much different snowpack. Expect areas of new windslab with some reasonable options for climbing and avoiding much of the troublesome snow (but not all). The Chute has reloaded in the zone between the choke and the upper rollover. Left Gully and Hillman’s were scoured pretty heavily. The Lower Snowfield has a lot of “isolated terrain features” that can have unstable snow. In the Little Headwall, there is a lot of windblown snow. I recommend going cautiously through here if you are one of the first today. I observed fresh crown lines this morning on the Lion Head Trail (summer traverse) and in the Gulf of Slides south snowfields.

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 8:15a.m. February 24, 2015. A new advisory will be issued tomorrow.

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

2015-02-24

 Posted by at 8:09 am