Avalanche Forecast for Monday, January 7, 2019

This forecast was published 01/07/2019 at 7:45 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

New snow and sustained extreme wind since yesterday afternoon have resulted in small to large wind slabs. Areas have also been scoured to older snow and melt-freeze crust. Drifted snow that is smooth and pillowy in appearance is of most concern today. Avoid travel on and below these features. All forecast areas have MODERATE avalanche danger today, with LOW avalanche danger in the Northern Gullies of Huntington Ravine and low elevation areas such as in Crawford Notch being the exceptions. Our avalanche problem varies greatly across the terrain, so be sure to make careful observations to guide your terrain decisions.

2019-1-7 Printable One-Page PDF

Danger Rating by Zone

Mountain Weather

Five inches of new snow and 0.39 inches of snow water equivalent were recorded on the summit in the past 24 hours, with nearly four at Hermit Lake and three at Gray Knob. Wind has blown from the NW, in the 70-90 mph range on the summit, with four hours early this morning sustained around 90 mph and stronger gusts. Snowfall stopped last night.Wind remains NW at 70 mph and should shift N while tapering dramatically to under 20 mph by dark today. An inbound storm will bring snow starting around midnight tonight and continue through much of tomorrow, with S and SW winds to 60 mph. Total snowfall may be around 6”.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

Expect wind slabs formed on last night’s extreme wind speeds to vary in size, distribution, and sensitivity. You are most likely to find these slabs on the eastern half of the compass rose and while largely stubborn to a human trigger, softer pockets may be reactive. Traveling on scoured areas to avoid the avalanche problem may be an option. Though many pockets will only be capable of producing a small avalanche today, large areas of new wind slab do exist and could combine with pre-existing snow to produce a large avalanche.

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

The past week has brought complexity back to our upper snowpack. Modest amounts of snow have been affected by multiple rounds of strong and extreme wind that has generally blown out of the west and northwest. We don’t expect an avalanche to initiate in these layers, but they could ultimately be entrained and contribute to the overall size of an avalanche in surface slabs. Surface wind slabs are the primary concern today, and determining their location following last night’s wind should be your primary field observation goal today. Wind last night has scoured a significant portion of our terrain, particularly on the west side of the range where the robust December 22 melt-freeze crust has recently been the dominant snow surface. A natural avalanche did occur sometime in the past 24 hours in Center Bowl of Tuckerman Ravine, and while we have passed peak instability, it’s certainly a day to make careful observations and terrain choices in and below avalanche terrain.

Additional Concerns

The Sherburne and Gulf of Slides ski trails are snow covered to Pinkham Notch.

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
05/20/19
05:30
0 CM 20.4 MM0CM68 CM11.0 C12.0 C3.5 CObscuredNo precipitation
05/19/19
05:25
0 CM 0.0 MM0CM72 CM4.0 C6.0 C2.0 COvercastNo precipitation
05/18/19
05:20
0 CM 7.6 MM0CM80 CM1.0 C6.0 C1.0 COvercastNo precipitation
05/17/19
05:25
0 CM 0.8 MM0CM84 CM4.0 C10.0 C0.0 CClearNo precipitation
05/16/19
05:20
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 01/07/2019 at 7:45 AM.

Ryan Matz, Snow Ranger
USDA Forest Service
White Mountain National Forest