Avalanche Forecast for Friday, December 28, 2018

This forecast was published 12/28/2018 at 7:18 AM.
A new forecast will be issued tomorrow.

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

Expect freshly forming wind slabs to be touchy to human triggers today. As new snow and wind drifts accumulate through the morning, natural avalanches will become likely, and may become more likely as snow turns to sleet and rain this afternoon. Avalanche danger may rise to CONSIDERABLE today in all mid and upper elevation forecast areas not facing directly southwest.

You can avoid these avalanches by staying on low angle or lower elevation terrain that does not have deep new snow or wind drifted snow. Travelling in longer avalanche paths will expose you to the risk of natural avalanches from above. Gusty and erratic wind that loads slopes with more snow could trigger these avalanches unexpectedly.


Danger Rating by Zone

Mountain Weather

Light snow began falling around 2am this morning and has picked up in intensity with sleet mixing in already, despite the ground level air temperature of 7F. Snow will continue through the morning on westerly then southwesterly wind around 60 mph. So far this morning, wind has been gusty and a bit erratic. Sleet will likely continue to mix in this morning, adding weight to the forming wind slabs, before a change over to freezing rain and rain later in the day. Precipitation will switch back to snow tonight with upslope snow showers delivering another couple of inches tomorrow.

Primary Avalanche Problem – Wind Slab

Wind Slab




Small to medium sized wind slab avalanches will be able gather enough snow to be dangerous, particularly considering the icy bed surface beneath. These wind slabs will grow increasingly unstable through the day as new mixed precipitation types falling on the snow adds stress to the weak snow near the icy bed surface.

What is a Windslab Avalanche?

  Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Snowpack and Avalanche Discussion

Air and upper snowpack temperature recordings this morning are not favorable for new snow to bond to the existing, icy snow surface. This hard rain crust is widespread through our terrain and was the result of the 3” rain event on December 21-22. Despite losing almost 25cm of snow during that event, our avalanche paths are still well developed but with rocks, boulders, and ice cliffs now showing again. Given the glazed over snowpack and cold temperatures associated with this morning’s new snow, it would be wise to view the exposed boulders, bushes and cliffs in our avalanche paths as potential obstacles and not as anchors. Today’s avalanche problem is more of an angry badger backed into a corner than a burly grizzly bear.

Additional Concerns

The Sherburne and Gulf of Slides ski trails have patches or water ice and some recently exposed rocks mixed with the refrozen rain crust. New snow will obscure these obstacles.

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

Density (%)HSTTotalAir TT MaxT MinSkyPrecipComments
0 CM 20.4 MM0CM68 CM11.0 C12.0 C3.5 CObscuredNo precipitation
0 CM 0.0 MM0CM72 CM4.0 C6.0 C2.0 COvercastNo precipitation
0 CM 7.6 MM0CM80 CM1.0 C6.0 C1.0 COvercastNo precipitation
0 CM 0.8 MM0CM84 CM4.0 C10.0 C0.0 CClearNo precipitation
0 CM 0.0 MM0CM84 CM1.0 C1.5 C0.0 CFewNo precipitation

Avalanche Log and Summit Weather

Daily Observations

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
05/18/1934 F26 F 0.06 in 0.5 in39 MPH74 MPH

300 (WNW)

05/17/1940 F28 F .22 in .05 in37 MPH81 MPH

300 (WNW)

05/16/1932 F25 F .03 in 04 in22.8 MPH40 MPH

310 (NW)

05/15/1926 F20 F .05 in .4 in32.1 MPH67 MPH

330 (NNW)

05/14/1928 F17 F .2 in 2 in19.1 MPH57 MPH

100 (E)

05/13/1928 F19 F .07 in 0.9 in34.6 MPH67 MPH

100 (E)

05/12/1931 F17 F 0 in 0 in20.5 MPH47 MPH

330 (NNW)

05/11/1932 F18 F .1 in 0 in53.6 MPH84 MPH

300 (WNW)

05/10/1944 F27 F .85 in 0 in50.1 MPH88 MPH

220 (SW)

05/09/1942 F20 F .04 in 0 in18.6 MPH44 MPH

190 (S)

05/08/1927 F18 F 0 in 0 in38.3 MPH65 MPH

330 (NNW)

05/07/1939 F26 F .54 in 0 in40 MPH66 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 12/28/2018 at 7:18 AM.

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