Avalanche Forecast for Monday, March 16, 2020

This information was published 03/16/2020 at 7:10 AM.
A new forecast will be issued tomorrow.

NOT THE CURRENT FORECAST

This is an archived avalanche forecast and expired on 03/16/2020 at midnight.


The Bottom Line

Conditions that create a long sliding fall hazard persist. Warm rain followed by a re-freeze Friday night has left most of the open snowpack firm, icy and smooth where an unexpected stumble can lead to sliding downhill at an accelerating rate that quickly becomes too fast to self arrest.  Mitigate this hazard in steep terrain by using tools that keep you firmly connected to the snow including crampons, ice axe, and rope belay where appropriate.

For skiers and snowboarders looking for sun softened snow, south aspects may soften today, or they may not. If they do soften a little, it may not be enough to eliminate the sliding fall hazard, and remember that once the afternoon sun passes the softened snow will very quickly flash freeze. Avalanche danger is LOW today.

2020-3-16 Printed Forecast


Mountain Weather

Yesterday, an overcast morning cleared to blue skies with temperatures reaching 7F on the summit of Mt Washington and 28F at Hermit Lake. Wind from the NW was moderate and consistent at 35 to 45 mph for the daylight hours. Bright sun may not have been enough to soften snow on southern aspects.

Today, another day of clear skies and temperatures in the single digits F. North west wind will shift SW midday at 15-25 mph and increase to 30-45 mph and higher after dark. Up to an inch of snow is possible tonight from snow showers. 

Tomorrow snow is forecast to begin before sunrise and continue through the day with 1 to 3” or more at higher elevations from almost 0.5” of water. Wind is expected to be from the S for roughly the first half of the storm, shifting W for the second half of the storm. Temperatures on the summits will reach the lower 20sF. At this time, it looks like the freeze line will be around 3500’. Locations below 3500’ will see some rain as temperatures warm midday. Avalanche danger will increase if we see the upper end of possible snow totals.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

Thin wind slabs can be found in locations that were protected from the extreme winds Friday and Saturday. In some areas these wind slabs will be firm and unreactive, and in other locations they will be encased in an ice crust with a softer layer of snow beneath. Areas that were scoured from the wind will be very firm, icy and smooth.

  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.

Forecast Discussion

Long sliding falls are a significant hazard in our terrain after a rain and re-freeze.  We include a list of accidents on our website as a learning tool for others. It’s helpful for all of us to read about the mistakes of others, reflecting on the decisions we make, and maybe even exposing a bad habit or two such as not putting crampons early or leaving your helmet on your pack for the climb. We also have a separate list for long sliding falls, since we see them often, and can be especially dangerous: 

https://mountwashingtonavalanchecenter.org/long-sliding-falls/

Yet to be added to this list: yesterday afternoon the Hermit Lake Caretaker and a Snow Ranger assisted a skier who fell and slid the full length of Right Gully in Tuckerman Ravine. His injuries required transportation to the road and an ambulance to a local hospital. 

Please take a few minutes to read through this list and remember that the simple steps we talk about often, including using crampons, stiff boots, ice axe and understanding the limits of practiced self-arrest can help keep you safe, making your day more fun. 

Thanks to this observation that pointed out slick conditions above the ravines.

Additional Information

The Sherburne and Gulf of Slides ski trails are snow covered to Pinkham Notch.

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.

Snow Plot Information

DateHN24HN24W
(SWE)
Density (%)HSTTotalAir TT MaxT MinSkyPrecipComments
04/13/20
06:15
0 CM 0.1 MM0CM206 CM-3.5 C7.5 C-7.0 COvercastRain
04/12/20
06:20
Trace 1.8 MMTrace216 CM-7.0 C-4.0 C-7.0 CFewNo precipitation
04/11/20
06:20
14 CM 23.1 MM 14%62CM222 CM-8.0 C-6.0 C-8.0 COvercastNo precipitation
04/10/20
06:30
53 CM 49.5 MM 12%NC200 CM-6.0 C-2.0 C-6.5 COvercastSnowView
04/09/20
06:25
0 CM 0.0 MM0CM158 CM-1.0 C8.0 C-4.5 CClearNo precipitation

Avalanche Log and Summit Weather

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
05/25/2054 F46 F 0.0 in 0.0 in18.7 MPH44 MPH

260 (W)

05/24/2054 F40 F 8.3 in 21 in8.3 MPH21 MPH

280 (W)

05/23/2055 F43 F 0.0 in 0.0 in15 MPH45 MPH

300 (WNW)

05/22/2055 F40 F 0.0 in 0.0 in37.4 MPH67 MPH

290 (WNW)

05/21/2053 F38 F 0.0 in 0.0 in29.4 MPH59 MPH

280 (W)

05/20/2050 F34 F 0.0 in 0.0 in29.4 MPH59 MPH

280 (W)

05/19/2041 F27 F 0.0 in 0.0 in15.3 MPH36 MPH

100 (E)

05/19/2050 F34 F 0.0 in 0.0 in11.4 MPH25 MPH

30 (NNE)

05/18/2045 F30 F 0.0 in 0.0 in14.7 MPH36 MPH

70 (ENE)

05/17/2040 F30 F 0.0 in 0.0 in17 MPH35 MPH

270 (W)

05/16/2037 F28 F .16 in 0.0 in38.8 MPH101 MPH

310 (NW)

05/15/2042 F32 F .95 inTrace 31.5 MPH95 MPH

250 (WSW)

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 03/16/2020 at 7:10 AM.

Jeff Fongemie
USDA Forest Service
White Mountain National Forest