Avalanche Forecast for Sunday, March 3, 2019

This forecast was published 03/03/2019 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

Wind slabs remain our primary avalanche problem today. LOW avalanche danger exists throughout the forecast area though the potential for small avalanches remains in isolated areas. Human triggered avalanches in these wind slabs are unlikely but not impossible. Normal precautions in your terrain management as well as in the gear that you carry is advised. The firm slabs in steep open terrain present a long sliding fall hazard so crampons, an ice axe, and an honest assessment of the consequences of a slip will also be useful today.

2019-3-3 Printable

Danger Rating by Zone

Mountain Weather

Around an inch of low density snow fell on the summit overnight and early this morning on moderate (40’s mph) summit winds from the WNW. Temperatures are starting in the single digits above zero and will rise to the teens on the summit and around freezing in Crawford Notch. Skies will clear and winds will diminish further today as high pressure passes by before tonight’s storm. Snow will begin shortly after dark tonight. Though most weather models show the low pressure tracking far enough off shore to keep snow totals on the modest side, between the storm and the upslope snow that follows we will have elevated avalanche danger tomorrow, especially as the west and northwest winds increase.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

Wind slabs may also be found at lower elevation locations and have presented clean shears though no sign of propagation has been evident since their formation in the extreme wind event on Feb 25th. At mid elevation areas, most of these wind slabs are firm and unreactive. There have been multiple observations of an upside down snow structure, particularly at lower elevations or some wind sheltered locations, but with no reports of significant cracking or collapsing. Wind sheltered terrain may contain softer wind slabs that are more stubborn than unreactive, so be increasingly cautious where hollow sounding snow and steep terrain intersect.

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

Snow that fell at higher elevations last night, like the light snowfall on Wednesday night, is unlikely to improve skiing conditions. The softest snow is found either at lower elevations or wind sheltered areas. Snow coverage has improved on the west side with an avalanche observation in the main gully of the Ammo recently which helped to fill in and cover some obstacles. The snowpack there remains thin with open water and the typical terrain traps in place. Lots of lines have been skied this week throughout the range, though no huge, soft snow induced grins have been observed. Technical ski mountaineering with careful crampon and ice axe equipped ascents, followed by cautious, short radius turns on the way down paints a clearer picture of what’s been happening. It’s not even close to spring yet at any elevation with a dynamic snowpack that continues to demand respect. Crowds of people on the Lion Head winter route are being reported so factor in wait times on the steep sections into your itinerary or consider an alternate route.

Additional Concerns

The Sherburne and Gulf of Slides ski trails are snow covered to Pinkham Notch. Thanks to those who have been submitting observations this week. These are very helpful to our forecast and the community so please keep them coming. Some issues involving iPhone photo uploads have been resolved so the sideways photo problem is no longer a problem.

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 03/03/2019 at 7:09 AM.

Frank Carus
USDA Forest Service
White Mountain National Forest