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
04/13/20
06:15
0 CM 0.1 MM0CM206 CM-3.5 C7.5 C-7.0 COvercastRain
04/12/20
06:20
Trace 1.8 MMTrace216 CM-7.0 C-4.0 C-7.0 CFewNo precipitation
04/11/20
06:20
14 CM 23.1 MM 14%62CM222 CM-8.0 C-6.0 C-8.0 COvercastNo precipitation
04/10/20
06:30
53 CM 49.5 MM 12%NC200 CM-6.0 C-2.0 C-6.5 COvercastSnowView
04/09/20
06:25
0 CM 0.0 MM0CM158 CM-1.0 C8.0 C-4.5 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
05/25/2054 F46 F 0.0 in 0.0 in18.7 MPH44 MPH

260 (W)

05/24/2054 F40 F 8.3 in 21 in8.3 MPH21 MPH

280 (W)

05/23/2055 F43 F 0.0 in 0.0 in15 MPH45 MPH

300 (WNW)

05/22/2055 F40 F 0.0 in 0.0 in37.4 MPH67 MPH

290 (WNW)

05/21/2053 F38 F 0.0 in 0.0 in29.4 MPH59 MPH

280 (W)

05/20/2050 F34 F 0.0 in 0.0 in29.4 MPH59 MPH

280 (W)

05/19/2041 F27 F 0.0 in 0.0 in15.3 MPH36 MPH

100 (E)

05/19/2050 F34 F 0.0 in 0.0 in11.4 MPH25 MPH

30 (NNE)

05/18/2045 F30 F 0.0 in 0.0 in14.7 MPH36 MPH

70 (ENE)

05/17/2040 F30 F 0.0 in 0.0 in17 MPH35 MPH

270 (W)

05/16/2037 F28 F .16 in 0.0 in38.8 MPH101 MPH

310 (NW)

05/15/2042 F32 F .95 inTrace 31.5 MPH95 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 12/17/2019 at 9:45 AM.

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