Avalanche Forecast for Tuesday, February 26, 2019

This forecast was published 02/26/2019 at 7:09 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 wind slabs that are possible to trigger should be your primary avalanche concern if you brave the extreme wind and frigid temperatures today. Continued wind loading on these new slabs should also keep natural avalanches initiating in steep overhead terrain on your radar. While unlikely, recent snow and loading make it prudent to assume a natural avalanche could occur in locations with the greatest upwind fetch until you can determine otherwise. Wind affected snow can be found at lower elevations where you’re most likely to find reactive wind slabs today. MODERATE avalanche danger exists for all forecast areas. Make careful observations of our variable upper snowpack to guide your terrain decisions today.

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Danger Rating by Zone

Mountain Weather

Snowfall yesterday and last night ended around midnight, totaling over 8 inches at the summit with less at lower elevations. Wind from the W and NW has been sustained at over 100 mph on the summit for all but a few hours since late Sunday night. Several hours last night were in the 120-140 mph range with a peak gust of 171 mph. Today and tonight wind should remain NW around 80 mph with temperatures in the teens below 0F. A trace to one inch of snow is forecast as clouds decrease today. Expect no snowfall tomorrow as wind speeds finally drop significantly.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

Fresh wind slabs are the primary avalanche problem for all elevations today. You’re most likely to find them on the eastern half of the compass rose, with stubborn slabs at middle elevations and the potential for reactive but smaller wind slabs at lower elevations. No recent visual observations of higher terrain combines with wind continuing to affect the upper snowpack to provide a healthy dose of uncertainty today. Look for smooth wind drifted snow to identify the avalanche problem wherever you travel today and expect great variability in the wind’s effect on the snow 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

The notable wind event that is tapering slightly but continuing today will make for varied upper snowpack conditions of hard wind slab, heavily wind textured snow, and scouring to old crusts. You can also expect to find wind affected snow at low elevations which is also where you’re most likely to find reactive wind slab today. The unique recent weather factor was continued snowfall with significant accumulation on the extreme wind yesterday and last night. This somewhat rare occurrence of significant snowfall through peak wind speeds of a storm lends uncertainty to today’s forecast. We will undoubtedly have an interesting aftermath of this snow and wind event when visibility returns. Continued wind loading today should couple with potentially wide spatial variability in motivating you to carefully and continually assess snowpack if you venture into steep 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
05/22/19
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 02/26/2019 at 7:09 AM.

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