Avalanche Forecast for Monday, April 22, 2019

This forecast was published 04/22/2019 at 6:59 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

Wet avalanches and springtime hazards will present equal danger to those traveling in avalanche terrain today. Wet loose avalanches, commonly known as sluffs to skiers and riders, will be possible to initiate in steep terrain, but can easily be managed by moving to the side and letting debris pass. The outside threat of a wet slab, while unlikely, makes lingering under avalanche paths a poor choice. All forecast areas have LOW avalanche danger. Holes where  the snowpack in undermined by flowing water, both obvious ones and others that may open today, horizontal glide cracks near cliffs, and falling ice and rock will further complicate travel. Many of these spring hazards can be avoided by travel management, particularly if you can see where the hazards will present themselves.

Printable 2019-04-22

Danger Rating by Zone

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.

Mountain Weather

After a wet weekend, today looks like we’ll get a break, though the April showers weather pattern will likely continue this week. High temperatures yesterday were 45F on the Summit and 50F at Hermit Lake. Rain in the morning produced 0.21”. Today, light wind from the SE may increase to 20mph from the NE this evening. Fog interspersed with sunshine to start the day will give way to increasing clouds. Rain should hold off until the evening hours, with up to ¼” arriving tonight. Mostly cloudy skies with possible rain Tuesday will give way to a chance of below freezing temperatures overnight tomorrow.

Primary Avalanche Problem – Wet Loose

Wet Loose

Aspect/Elevation

Likelihood

Size

Wet loose avalanches will be small and slow moving. These are likely to be caused by skier induced sluff and can be managed by waiting off to the side and letting this sluff move downhill first. Such sluffs are often small enough that they won’t bury you, but could easily carry a person towards other hazards like an opening glide crack or over an ice bulge if they catch you unaware.

What is a Wet Loose Avalanche?

  Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

Secondary Avalanche Problem – Wet Slab

Wet Slab

Aspect/Elevation

Likelihood

Size

The wet slabs that remain a relevant avalanche problem are largely driven by our concerns of significant water running under the snowpack. A thorough soaking of the snowpack this past weekend penetrated deep into the snow and likely stabilized most deep layers of concern. Today’s weather will continue to drive warmth into the snow, but we are likely close to a fully isothermal snowpack, making deeply buried weak layers less likely to drive a wet slab.

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

For those who have not had eyes on the snowpack since last week, expect to see major changes the next time you visit. Falling apart or shrinking rapidly are accurate ways to describe what’s currently going on in avalanche terrain. Springtime hazards are appearing and the following should be discussed equally with avalanche hazards today:

  • Opening creeks and streams
  • Holes near trees, rocks, and cliffs
  • Undermined snow that could easily collapse
  • Glide cracks on wide open snow slopes
  • Falling ice

We believe the time of rapid change has passed and the snowpack is becoming more stable. That being said, the weather pattern we are currently experiencing (above freezing temperatures since Thursday evening) could be described as a little weird. Weird weather has the potential to create weird avalanches. A freeze will help, but a solid freeze looks far off at the moment. All this indicates the snowpack is trending toward stable, but the time to let your guard down has not yet arrived.

Additional Concerns

The Sherburne and Gulf of Slides ski trails are deteriorating quickly. Expect water crossing to be the big challenge, along with bare patches, exposed rocks, and ice.

Details on daily snowfall totals, precipitation type, total depth of snow and other information can be found on our page devoted to snow study plot data. Click here to check it out.

Recent snowpack and avalanche observations can be found here and on Instagram. Your observations help improve our forecast product. Please take a moment and submit a photo or two and a brief description of snow and avalanche information that you gather in the field.

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
05/19/1951 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)

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)

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 04/22/2019 at 6:59 AM.

Helon Hoffer
USDA Forest Service
White Mountain National Forest