Avalanche Forecast for Saturday, January 19, 2019

This forecast was published 01/19/2019 at 7:21 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

The coming winter storm will create conditions that might meet avalanche warning criteria, but today is a different story. Small pockets of wind slab formed last night add some spice to generally stable conditions. You could trigger one of these new small slabs, but they should be easy to avoid. All forecast areas have LOW avalanche danger. Widespread areas of hard snow will make long sliding falls as much of a concern in your travel this morning, and consider that visibility will generally deteriorate through the day. Using normal caution for avalanche terrain and remembering that Low doesn’t mean no avalanche danger should make today the safest conditions of the holiday weekend.

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Danger Rating by Zone

The USDA  Forest Service Mount Washington Avalanche Center has issued a backcountry avalanche watch for the Presidential Range.  Avalanche Watch criteria may also be met in other areas outside those forecast by the avalanche center. This avalanche watch does not apply to operating ski areas.

Avalanche danger will increase through Sunday and Monday,  January 20-21, 2019 creating dangerous avalanche conditions. Widespread natural avalanche activity will be possible, especially on Monday, January 21.

A potent winter storm arrives this evening  and will continue through Sunday, January 20. Expected heavy snowfall will combine with strong winds to create unstable conditions. Strong NW winds on Monday, January 21 will create conditions for very large avalanches.

Mountain Weather

Around 1” of new snow yesterday was affected by westerly wind that increased to the 60-80 mph range for much of last night. Wind is currently diminishing and will continue to do so through daylight hours. High temperature should be a few degrees colder than yesterday’s summit high of 10F, with summit temperatures in the lower single digits. Increasing cloud cover today will ultimately bring heavy snow that will begin falling in light amounts this afternoon and intensify nearer to midnight. Heavy snow should continue continue through most of tomorrow, tapering to lighter precipitation rates by evening. Snow totals currently look to be around 15” but could be more. Through the snow storm, wind is forecast to shift from SW at dawn tomorrow through E and NE by afternoon, ultimately blowing from the NW by tomorrow night. Wind speeds will increase with this shift, from 25 mph tonight to around 50 mph or stronger by tomorrow night.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

New wind slabs formed overnight should be reactive to a human trigger but small in size. While either of relatively little concern or easily avoidable, remember that small avalanches in the wrong place can be a big deal. We expect you’ll find these isolated pockets on the eastern half of the compass rose.

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

A mixed bag of upper snowpack and surface conditions precede the inbound winter storm. Most of our avalanche start zones have a relatively smooth snow surface, with a few exceptions of heavily wind textured snow and less developed paths on the west side. Snow and wind last week created this mix of layered wind slabs which vary in density and are generally quite hard and unreactive. Pockets of softer wind slab do exist in the terrain, both in the form of reactive but small new wind slabs and more stubborn, older pockets. For Sunday and Monday, consider our current mix of relatively smooth bed surfaces on thick hard slabs, some potential for an avalanche to step down to deeper layers in softer pockets, and that the December 22 crust is still present at or near the surface in some scoured locations.

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
05/22/19
05:25
Trace 6.2 MMTrace60 CM0.5 C2.0 C-1.0 CClearNo precipitationView
05/21/19
05:25
0 CM 4.2 MM0CM60 CM2.0 C15.0 C2.0 COvercastNo precipitation
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

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
05/21/1934 F23 F .57 in 1.9 in73 MPH135 MPH

330 (NNW)

05/20/1951 F33 F 0.57 in 0.0 in48 MPH82 MPH

250 (WSW)

05/19/1951 F34 F .6 in 0 in34.2 MPH66 MPH

250 (WSW)

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)

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 01/19/2019 at 7:21 AM.

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