Avalanche Forecast for Wednesday, January 9, 2019

This forecast was published 01/09/2019 at 7:06 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

Heavy snow with growing wind speeds are the clear indicators of today’s avalanche problem. Unfortunately, low visibility will make direct observation of this growing avalanche problem difficult. Lower angled terrain may provide excellent riding conditions but avoiding the runouts of avalanche paths will be key for safe travel today, especially as wind picks up this afternoon. Periods of heavy snow today, combined with snow on the ground from yesterday, will provide plenty of snow for avalanches that will be large enough to easily bury a person. The newly formed slabs will likely be touchy as well. Avalanche danger will rise to CONSIDERABLE today, especially where wind slabs build. Lower elevation, wind sheltered terrain will have MODERATE avalanche danger with smaller human-triggered avalanches still possible in steep terrain.

2019-01-09 Printable PDF

Danger Rating by Zone

Mountain Weather

A few inches (7cm) of snow fell on Mount Washington yesterday with a couple inches more in the mountains south of the notches. Precipitation type remained snow at higher elevations with mixed precip and rain in the valleys and was accompanied by light wind from the south through west. The second low pressure system passing today will deepen offshore and create bands of snow which will bring up to 8” of snow to our forecast area by late afternoon with more falling into the evening. Temperatures will fall through the day as wind slowly ramps up and shifts to the northwest and reaches strong loading speeds in the afternoon. All the warm moist air in the region will keep conditions ripe for thick fog as well as continued upslope snow showers through the night and into tomorrow.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

Wind slab avalanches will grow in size as well as in likelihood of triggering today as new snow is loaded into slopes and gullies, generally on the east side of the range. Crossloading of other aspects will also be likely. Natural avalanches will become increasingly likely later in the day.

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.

Secondary Avalanche Problem – Dry Loose

Dry Loose

Aspect/Elevation

Likelihood

Size

Dry Loose avalanches, a.k.a. sluffs, could be a problem in steep terrain and may help trigger a larger wind slab avalanche where these exist from previous wind loading and sluffing. Examples of this would be in the middle of Sluice and below Headwall ice in Tuckerman Ravine.

What is a Dry Loose Snow Avalanche?

   Dry Loose avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.

Snowpack and Avalanche Discussion

The 3” of new snow which fell in the past 24 hours was barely affected by wind yesterday. That new snow fell on mostly stubborn wind slabs and some exposed ice crust in more wind hammered areas. The more dynamic winter weather at higher elevations over the past week has made for a more varied and dynamic upper snowpack. Most of the instabilities prior to today are stubborn wind slabs built over the weekend and while stubborn and primarily glued to underlying crusts, a heavy load today could break a larger slab loose.

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 01/09/2019 at 7:06 AM.

Frank Carus
USDA Forest Service
White Mountain National Forest