General Bulletin for Saturday, November 24, 2018

This forecast was published 11/24/2018 at 7:00 AM.
A new bulletin will be issued when conditions warrant.

The Mount Washington Avalanche Center will no longer issue daily avalanche forecasts for the 2018/19 season. Read more

The Mount Washington Avalanche Center will no longer issue daily avalanche forecasts for the 2018/19 season. Instead, we will post an updated General Bulletin as needed, in case of significant snow or weather events that might vary from the typical daily changes that come with spring weather. We will also keep you informed about the official closure of the portion of the Tuckerman Ravine Trail from Lunch Rocks through the Lip and Headwall as well as the switch from the Lion Head Winter Route to the summer trail. Observations from the field will continue to be a valuable resource, so please keep submitting photos, videos and observations here and we will do the same. Check the Forecast page for update on Sherburne Trail closures, which are imminent as spring snowmelt continues.

The switch to a General Bulletin does NOT mean that the mountains are now a safe place to ski. The hazards which emerge in the spring are significant and require careful assessment and strategic management. If you have never skied Tuckerman, peruse our Incidents and Accidents page for spring related incidents involving avalanches, long sliding falls, icefall, crevasse and moat falls, and other incidents related to diurnal changes in the snowpack. These will help you understand and plan for these hazards.


The Bottom Line

General Bulletins are issued when unstable snow may exist within our forecast areas but before 5-scale avalanche forecasts begin. We will start 5-scale forecasts on Wednesday, November 28 which will include an added forecast for the Northern Presidential range, 7 total forecast areas for Huntington and Tuckerman Ravines and a new layout to help you identify avalanche problems in the field. Please remember that avalanches can and do occur before daily 5-scale avalanche forecasts are issued.

A passing cold front brought intense snow squalls Tuesday afternoon and added another 4.5” to the 4” of snow that fell the day prior. So far this month, the summit has recorded 44” of snow and the steep east facing terrain is showing clears signs of this snowfall. Continuous snow slopes in Tuckerman Ravine, with its great amount of fetch, have grown considerably in the past two days following high wind speeds and intense wind loading. Gulf of Slides gullies are also filling out with avalanche debris reported in Gully 1 and 3. Debris from several natural avalanches was also observed in the center and left side of Tuckerman Ravine and likely occurred Tuesday afternoon or early Wednesday. Some wind-transported snow was flying at the ridgetops early this morning meaning many of the existing wind slabs are fairly recent and may not be fully bonded to snow beneath. Low temperatures slowly rose from -26F on Thursday but remained cold enough through Friday to further delay the stabilizing process.

Danger Rating by Zone

If you are planning to take advantage of the warming temperatures Saturday, expect to find firm wind slabs with pockets of softer snow in a few sheltered areas. There is a sugary layer beneath the melt/freeze crust to keep on your radar. This layer may have failed during the most recent avalanche cycle, and could still be a player in the unlikely event you trigger one of the more recent hard slabs. Probe with your ski pole handle or ice axe, dig a pit or do hand shears before committing to a slope. Don’t let the firm nature of the slab lull you into thinking that it can’t avalanche. Remember that the first warming of a cold snowpack, such as we’ll see to some extent on Saturday,  can spell trouble as slabs loose strength. Snow will arrive Saturday night and may turn to sleet or rain at Ravine elevations on Sunday.  A more significant storm is forecast for Monday and Tuesday. Stay tuned and remember that wind loading can turn a few inches of snow into a thick wind slab in our windy terrain.

Ice climbs are growing in size and pockets of unstable snow between ice pitches are notorious for causing problems.  In addition to avalanche hazards, remember to take into account other early season hazards that exist in the terrain:

  • Rocks, trees and bushes lurk in the snow and in the fall line. Skiing or sliding into obstacles can ruin your day or worse. New snow may just barely cover a season ending stump or boulder.
  • Terrain traps and cliffs make burial and significant injury a real possibility, even if you are only swept off your feet by a small avalanche.

The Winter Lion Head Route is open. This route avoids the avalanche paths that threaten the summer trail and is the most direct route to the summit from the east side. Be advised that all the recent snowfall drifted chest deep near treeline, making snowshoes more than just a good idea on Saturday!

We have received some great snow and avalanche observations from folks in the field. Thanks, and keep them coming!

Avalanche Safety Information Study

Please contribute to the effort to improve backcountry avalanche forecasts! Researchers in Canada devised a study to better understand how we communicate the avalanche risk, and we need your help. Please fill out this survey. It will take a few minutes, but it will help us as we work on new ways to give you the most important avalanche information.

Snow Plot Information

DateHN24HN24W
(SWE)
Density (%)HSTTotalAir TT MaxT MinSkyPrecipComments
05/31/19
05:20
0 CMTrace 0CM0 CM8.0 C11.0 C0.5 CBrokenNo precipitation
05/30/19
05:25
0 CM 0.0 MM0CM0 CM7.5 C7.5 C1.0 CScatteredNo precipitation
05/29/19
05:25
0 CM 22.3 MM0CM0 CM1.5 C4.0 C0.0 COvercastNo precipitation
05/28/19
05:25
0 CM 0.0 MM0CM0 CM0.5 C11.0 C0.5 CClearNo precipitation
05/27/19
05:15
0 CM 0.0 MM0CM10 CM8.0 C15.5 C8.0 CClearNo precipitation

Avalanche Log and Summit Weather

Thank you Mount Washington Observatory for providing daily weather data from the summit of Mount Washington.

DateMax TempMin TempTotal (SWE)24H Snow & IceWind AvgWind Fastest MileFastest Mile DirAvalanche Activity
05/30/1946 F36 F 0 in 0 in27.9 MPH55 MPH

290 (WNW)

05/29/1947 F33 F 0 in 0 in20 MPH48 MPH

290 (WNW)

05/28/1934 F28 F .71 in 3.7 in20 MPH48 MPH

290 (WNW)

05/27/1940 F27 FTrace 0 in38.9 MPH68 MPH

300 (WNW)

05/26/1948 F39 F .77 in 0 in48.7 MPH75 MPH

290 (WNW)

05/25/1947 F31 F .42 in 0 in17.7 MPH63 MPH

240 (WSW)

05/24/1942 F32 F .66 in 0 in44.8 MPH105 MPH

05/23/1944 F30 F .16 in 0 in26.8 MPH71 MPH

270 (W)

05/22/1934 F21 F 0 in 0 in36.2 MPH115 MPH

330 (NNW)

05/21/1934 F23 F .57 in 1.9 in73 MPH135 MPH

330 (NNW)

05/20/1951 F33 F 0.57 in 0.0 in48 MPH82 MPH

250 (WSW)

05/19/1951 F34 F .6 in 0 in34.2 MPH66 MPH

250 (WSW)

Please Remember:

Safe travel in avalanche terrain requires training and experience. This forecast 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.

Avalanche danger may change when actual weather differs from the higher summits forecast.

For more information contact the US Forest Service Snow Rangers, AMC visitor services staff at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or seasonally at the Harvard Cabin (generally December 1 through March 31). The Mount Washington Ski Patrol is also available on spring weekends.

Posted 11/24/2018 at 7:00 AM.

Frank Carus, Lead Snow Ranger
USDA Forest Service
White Mountain National Forest