Avalanche Forecast for Monday, December 24, 2018

This forecast was published 12/24/2018 at 6:52 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

Pockets of small wind slab that a human could trigger can be avoided by travelling on our widespread refrozen snow surface. All forecast areas have LOW avalanche danger. The hard, slick, refrozen snow present in our steep terrain makes long sliding falls a significant hazard today. Crampons, an ice axe, and your ability to use them effectively to avoid a fall are crucial for safe travel in the alpine. On our ice climbs, continue to be mindful of possible ice dams, or flowing water building pressure beneath recently frozen ice that could break with the placement of a tool or crampon.

2018-12-24_Printable_PDF

Danger Rating by Zone

Mountain Weather

Clear skies and temperatures in the teens F yesterday have given way to a weak low pressure system that is bringing cloud cover to the Presidential range. Clouds should persist all day, though we may see a few breaks this afternoon. Minimal to no precipitation is forecast as temperatures remain within a few degrees of the current 11F on the summit. Current summit wind is 25 mph from the W and may increase slightly while holding this general direction. For those planning to get into our mountains on Christmas, expect similar temperatures and slightly stronger wind than today under clear skies.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

Isolated wind slabs exist in the terrain and can generally be found on the eastern half of the compass rose. Formed Saturday night and into Sunday morning, these new pockets should range from stubborn to reactive to a human trigger. Plenty of opportunities exist to avoid these isolated slabs on our larger slopes, but it’s possible that our narrowest gullies could hold sections of wall to wall wind slab.

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 3” of rain and sustained above freezing temperatures last week were followed by the current cold temperatures that have solidly refrozen our snowpack. The Lip in Tuckerman Ravine produced a large wet slab avalanche sometime during the rain storm, possibly late Friday or early Saturday. Our refrozen hard snow surface is actually quite smooth in many areas. The minimal new snow Saturday had enough ability to stick to the older snow to make most of our snow surfaces bright white in appearance, but recently formed wind slabs are the exception rather than the rule.

Additional Concerns

The Sherburne and Gulf of Slides ski trails are mostly snow covered to Pinkham Notch, but expect melted out areas to provide challenging conditions.

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 12/24/2018 at 6:52 AM.

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