General Bulletin for Tuesday, December 17, 2019

This information was published 12/17/2019 at 9:45 AM.
A new bulletin will be issued when conditions warrant.


The Bottom Line

New snow and wind loading over the next several days will combine to form wind slabs that may be sensitive to a human trigger as the new snow struggles to bond to the frozen bed surface resulting from the deep freeze after Saturday’s warm rain.

Even a small avalanche can be deadly if it turns into a long sliding fall especially in an early season snow pack filled with rocks, trees and exposed cliffs. With up to 10” of new snow possible this week, newly formed wind slabs may be large enough to bury a person.

Safe traveling in and around avalanche terrain with this early season snow pack should include an extra dose of caution, keeping in mind the increased chance for bodily trauma will not be mitigated by your avalanche beacon and partners with shovels. Be continuously mindful of the terrain below you and objectively evaluate the consequences of a fall along your way. Get your crampons and axe out early, rope up before you think necessary, or look for ski terrain with a safe run-out.

2019-12-27-General Bulletin Printable

Danger Rating

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, January 15 or earlier, if possible. Please remember that avalanches can and do occur before 5-scale avalanche forecasts are issued.

Mountain Weather

Tuckerman Ravine 12/16/19

Tuckerman Ravine  12/16/19

Well over an inch of rain fell on across the Presidential range on Saturday, followed by a deep freeze creating a very hard frozen bed surface. A low pressure system on Tuesday followed by upslope snow showers at least into Wednesday brings the potential for up to 10” of new snow.

Wind on Tuesday will be moderate by Mount Washington standards, under 30 mph as it shifts through the SE before wrapping back around to the NW on Wednesday and ramping up with gusts Wednesday night expected to top 100 mph. Strong winds and very cold temperatures Wednesday night through Friday will make any travel challenging especially above treeline.

In addition to avalanche hazards, be mindful of 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, heightening the consequences of a fall or small avalanche.
  • Long sliding falls are a threat despite the appearance of new, soft snow on your approach. Wind can easily scour parts of your climb or hike down to a hard bed surface. What you thought would be a mellow snow climb can turn into something much more exciting. Consider using a rope in third class terrain or sooner than normal due to the slick surface.

The summer Lion Head Trail remains a preferred east side route to the summit over the Tuckerman and Huntington Ravine Trails, though watch for our recommendation towards the Winter Route that will come with additional snowpack development.

Snow Plot Information

DateHN24HN24W
(SWE)
Density (%)HSTTotalAir TT MaxT MinSkyPrecipComments
01/19/20
05:15
8 CM 7.3 MM 10%NC112 CM-6.5 C-6.5 C-15.0 COvercastSnow
01/18/20
05:15
0 CMTrace 0CM103 CM-18.5 C-12.0 C-22.0 COvercastNo precipitationView
01/17/20
05:11
22 CM 16.6 MM 9%26CM107 CM-20.0 C-4.0 C-22.0 CFewNo precipitation
01/16/20
05:15
3 CM 2.9 MM 11%NC85 CM-7.0 C-4.0 C-7.0 COvercastSnow
01/15/20
05:16
2 CM MM 16%NC82 CM-4.0 C-3.5 C-7.0 COvercastSnowView

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
01/17/204 F-18 F .03 in .4 in75 MPH110 MPH

320 (NW)

01/16/2018 F-11 F .048 in 6.1 in43.3 MPH117 MPH

330 (NNW)

01/15/2020 F11 F 0.25 in 1.8 in9.3 MPH74 MPH

290 (WNW)

01/14/2020 F10 F 0.03 in 0.7 in32 MPH69 MPH

280 (W)

01/13/2022 F14 F .04 in .8 in49.5 MPH81 MPH

240 (WSW)

01/12/2045 F8 F .84 in .4 in58.4 MPH104 MPH

260 (W)

01/11/2042 F29 F .32 in 0 in68.8 MPH119 MPH

230 (SW)

01/10/2030 F12 F .22 in 1.3 in63.4 MPH102 MPH

260 (W)

01/09/2015 F-14 F .04 in .4 in50.1 MPH114 MPH

310 (NW)

View
View
01/08/2013 F-8 F .52 in 5.2 in43.5 MPH95 MPH

290 (WNW)

01/07/2016 F1 F .17 in 1.6 in41.8 MPH90 MPH

280 (W)

01/06/2010 F3 F .2 in 2.2 in32.8 MPH71 MPH

270 (W)

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 12/17/2019 at 9:45 AM.

Jeff Fongemie, Snow Ranger
USDA Forest Service
White Mountain National Forest