Avalanche Forecast for Wednesday, March 6, 2019

This forecast was published 03/06/2019 at 7:23 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

Slopes with large areas of wind drifted snow could produce an avalanche from a human trigger today though natural avalanches are unlikely in all areas. The Headwall of Tuckerman Ravine and the Southern Gullies in Huntington hold the largest of these new wind slabs. These slabs are likely to be stubborn though a human-triggered avalanche on the larger side remains possible here following the wind loading that occurred yesterday and overnight. All forecast areas have MODERATE avalanche danger, with the Northern Gullies in Huntington Ravine as the exception with LOW avalanche danger. Be mindful that the soft snow you may be seeking is the avalanche problem today, and the old bed surface is firm requiring careful footwork with crampons.

2019-3-6 Printable PDF

Danger Rating by Zone

Mountain Weather

Just under and inch of new snow fell at higher elevations overnight on 40-50 mph W wind with cold temperatures that bottomed out at -15F. Today will be another unseasonably cold day with a high temperature in the teens below zero. The current 35-50 mph W wind will increase later this afternoon with gusts to 75 mph. Summits will remain mostly in the clouds with a chance of snow showers and up to an inch of new snow. Tomorrow is forecast to be cold as well with a high of -10F and another chance for snow showers.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

Wind slabs formed in the last 24 to 48 hours are the primary avalanche concern today. These slabs are generally firm and stubborn with softer and reactive pockets in wind sheltered terrain. These new slabs will be found primarily in start zones in the middle or lower areas of slopes and gullies in the ravines on the east side of the range.

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

Huntington Ravine March 5. A mix of new wind slab and old bed surface.

Our snowpack is a mix of new wind slab, and old bed surface. Stability tests yesterday low in Huntington Ravine and Tuckerman Ravine demonstrated moderate results, though only in the most wind protected locations. Generally the new slabs were firm (P) to the bed surface and likely to be unreactive in all but isolated areas in steepest terrain. Many places in our terrain are also wind scoured making skinning difficult and crampons useful. Pockets of wind slab can be a problem especially over steep or rocky terrain or terrain traps like you might find in west side gullies.

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.

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 03/06/2019 at 7:23 AM.

Jeff Fongemie
USDA Forest Service
White Mountain National Forest