Avalanche Forecast for Saturday, March 14, 2020

This information was published 03/14/2020 at 7:04 AM.
A new forecast will be issued tomorrow.

NOT THE CURRENT FORECAST

This is an archived avalanche forecast and expired on 03/14/2020 at midnight.


The Bottom Line

The snowpack in our forecast area was wetted at most elevations yesterday before refreezing under falling temperatures creating a sliding fall hazard in steep terrain. Watch for isolated pockets of wind slab in sheltered terrain that will be masking the icy surface below. Stiff boots, crampons, ice axe and the skills to use them are required basic tools to be safe today. Avalanche danger is LOW. Natural and human triggered avalanches are unlikely.

2020-3-14 Printed Forecast


Mountain Weather

Yesterday, the summit of Mt Washington recorded a mix of precipitation types including snow, ice pellets, and freezing rain resulting in just 1.4” total snowfall from the 0.43” of liquid precipitation that fell. Hermit Lake recorded 2.3” of snow, noting precipitation went from snow to sleet to rain then back to snow/sleet with a 2cm ice crust. Temperatures peaked at 32F around 3pm on a 70-90 mph W wind, before falling sharply as wind shifted W at 70-100 mph through the night. 

Today, west wind will shift NW and continue to rage at 70-90 with gusts up to 120 mph early, then ease off slightly through the day. Temperatures will remain in the upper single digits F with a chance of snow showers producing a trace to 1”.

Tomorrow, expect clearing skies with continued cold temperatures in the single digits above. North west wind at 50-60 mph. No snow is forecast.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

Small wind slabs formed from the 1.4” of new snow yesterday may be found in sheltered terrain and are likely unreactive. While this is a seemingly small avalanche problem, it can be a big hazard when barely covering a slick bed surface in steep terrain. 

  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

Yesterday’s mixed precipitation at mid and upper elevations was unlikely to eliminate the frozen surface, sliding fall hazard since Tuesday’s warm rain and the subsequent re-freeze. It’s likely that patches of new snow can be found, and while in some places the snow may be thick enough to hold an edge, in others the snow will be thin and barely covering the icy surface. With strong wind trying to push you off your feet, and the fact that a stumble can result in a sliding fall, today is a good day to dial back expectations. 

Additional Information

The Sherburne and Gulf of Slides ski trails remain 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
03/22/20
05:07
0 CM 0 MM0CM145 CM-18.0 C-5.0 C-18.0 CClearNo precipitation
03/21/20
05:10
Trace 1.6 MMNC145 CM-9.5 C12.0 C-9.5 COvercastSnow
03/20/20
05:05
0 CMTrace 0CM154 CM7.0 C8.5 C-4.5 CClearNo precipitation
03/19/20
05:10
0 CM 0.0 MM0CM156 CM-1.5 C3.0 C-7.5 CClearNo precipitation
03/18/20
05:41
1 CM 3.0 MM1CM157 CM-8.0 C-2.5 C-10.0 CFewNo precipitationView

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
03/20/2043 F20 F 0.31 in 0.2 in66.5 MPH145 MPH

260 (W)

03/19/2036 F14 F 0.02 in 03 in26.5 MPH50 MPH

180 (S)

03/18/2021 F9 F 0.03 in 0.5 in39.7 MPH94 MPH

290 (WNW)

03/17/2021 F6 F 0.25 in 2.1 in52.4 MPH109 MPH

280 (W)

03/16/2014 F1 F 0 in 0 in21.3 MPH50 MPH

240 (WSW)

03/15/207 F-3 F 0.0 in 0.0 in42.1 MPH71 MPH

300 (WNW)

03/14/2014 F6 F 0.09 in 0.7 in76.9 MPH117 MPH

270 (W)

View
03/13/2032 F12 F .43 in 1.4 in64.3 MPH94 MPH

270 (W)

03/12/2022 F14 F .02 in .2 in27.4 MPH48 MPH

210 (SSW)

03/11/2024 F9 F 0.02 in 0.2 in47.3 MPH85 MPH

300 (WNW)

03/10/2035 F24 F 0.45 in 0.5 in52.1 MPH97 MPH

260 (W)

03/09/2034 F21 FTrace Trace 57 MPH84 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 03/14/2020 at 7:04 AM.

Jeff Fongemie
USDA Forest Service
White Mountain National Forest