Avalanche Forecast for Thursday, January 24, 2019

This forecast was published 01/24/2019 at 7:11 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

Rain falling on existing wind slabs will make wet slab avalanches possible today. These wet slabs will be most likely in our steepest terrain where the upper snowpack is thinnest and resting on an icy bed surface. Human-triggered avalanches will be possible in these specific steep areas and earn a MODERATE danger rating.  Avalanches aren’t expected to be large except in the Lip/Headwall area of Tuckerman Ravine. That area has a history of producing larger natural avalanches during this kind of weather and so earns a CONSIDERABLE danger rating today. Avalanche risk, cold rain, an increasingly unsupportable snowpack, and wind blowing 70 mph and gusting to 90 mph make travel into avalanche terrain seem like an unattractive option.

2019-01-24 Print version

Danger Rating by Zone

Mountain Weather

The current warming trend began yesterday morning and brought balmy conditions in the morning until mixed wet snow, sleet and freezing rain arrived in the early afternoon. The temperature on the summit at 6am is 34F with 42F at 4000’ and rain now falling at all elevations. The summit temperature will continue to rise today and seems on track to easily reach 40F by early afternoon. By late afternoon or evening, precipitation should change back over to snow as temperatures fall with the arrival of a cold front. The summit temperature will drop to 7F by tomorrow morning.

Primary Avalanche Problem – Wet Slab

Wet Slab

Aspect/Elevation

Likelihood

Size

Rain and warm temperatures will combine to create a threat of wet slab avalanches. Water flowing through the upper layers of snow may impact weak, soft snow beneath. The increased risk of wet slab avalanches will remain as long as water flows through the snow today.

What is a Wet Slab Avalanche?

  Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.

Snowpack and Avalanche Discussion

Extreme wind on Monday night built wind slabs on the eastern half of the compass rose. These wind slabs are not especially thick in most higher start zones due to the scouring action of the wind there. Snow was pushed down into lower start zones such as the low angle ice in Odell Gully and the Lower Snowfields below Duchess. Field time was limited due to poor visibility since the extreme wind event but the theme of deposition in lower start zone or into the trees on the eastern half of the compass rose is a safe bet. Stiff wind slabs were even built in the woods, though it took a snow tractor to cause them to crack any distance. Higher in the terrain widespread avalanche debris was barely discernible due to the scouring action of the wind. Small and smooth wind slabs were visible in upper start zones, though they were likely very stubborn. The Dec 23rd ice crust remains a concern as a bed surface and remains the bed surface beneath the more recent wind slabs though at wildly varying depths.

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 01/24/2019 at 7:11 AM.

Frank Carus
USDA Forest Service
White Mountain National Forest