Avalanche Forecast for Tuesday, January 8, 2019

This forecast was published 01/08/2019 at 7:07 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 may form small wind slabs today, however the small to large wind slabs formed Sunday night remain the main concern today. Respect these areas of drifted snow that can be identified by their smooth and pillowy appearance. These relatively hard wind slabs are notoriously tricky to assess, so don’t let your guard down. Avalanche danger is MODERATE today for a majority of our forecast areas, with the Northern Gullies of Huntington Ravine and low elevations having LOW avalanche danger due to a lack of recently deposited snow.

2019-1-8 Printable One-Page PDF

Danger Rating by Zone

Mountain Weather

After mostly clear skies and diminishing wind yesterday, snow has begun to fall this morning. Just under an inch of snow has accumulated at Hermit Lake. Overnight winds reached 50 mph out of the S and have shifted SW. Snowfall should taper off by noon, with another inch or two accumulating. Wind should remain SW and begin to diminish late morning today, ultimately to around 20 mph by dark. Our terrain may receive up to a tenth of an inch of freezing drizzle this afternoon. Tonight, precipitation should intensify again and fall as all snow. Heaviest snowfall is expected tomorrow morning.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

New snow overnight and this morning may form small new wind slabs, but the larger avalanche problem remains the wind slabs formed Sunday night into yesterday morning. These slabs can specifically be found on the eastern half of the compass rose and vary from inches to possibly several feet thick. Areas of scouring and heavily wind textured sastrugi snow can be found, and we expect scouring to be prevalent on the west side of the range. The smooth and generally smooth wind slab will be stubborn to a human trigger today, though it is the dominant snow surface in select easterly terrain and remains capable of producing a large avalanche in such terrain.

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

Several layers of wind slab formed over the past week comprise our upper snowpack. Those formed Sunday and into early Monday remain the primary concern, though are generally hard and therefore stubborn to a human trigger. The extreme wind speeds early yesterday also resulted in scoured areas and heavily textured snow. Visually locating the smooth wind slabs which are the avalanche problem remains a key field observation. It may be possible to avoid the avalanche problem given good visual observations. With more snow on the way, be aware that while stubborn to a human trigger these slabs may contribute to the overall size of potential avalanches tomorrow. Further, the chance of freezing drizzle this afternoon will proceed tonight’s heavy snowfall and may result in an icy crust beneath new slabs tomorrow.

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 01/08/2019 at 7:07 AM.

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