Avalanche Forecast for Wednesday, February 19, 2020

This information was published 02/19/2020 at 7:05 AM.
A new forecast will be issued tomorrow.

NOT THE CURRENT FORECAST

This is an archived avalanche forecast and expired on 02/19/2020 at midnight.


The Bottom Line

Howling wind will move snow from the ground into eastern ravines and gulfs. Wind slabs will exist today on multiple aspects due to the shift in wind direction. CONSIDERABLE avalanche danger exists on northerly through easterly aspects of the range. Very large and far running dry slab avalanches are possible in Tuckerman Ravine, Hillman’s Highway and to a lesser extent in the Gulf of Slides. In these and similar locations, slopes could avalanche naturally due to the stress of continued wind loading. 

  • Dangerous avalanche conditions exist in and below wind loaded terrain.
  • Human triggered avalanche are likely today.
  • Keep your terrain choices conservative, or better yet ski, ride or climb in wind sheltered lower elevation areas.
  • Avalanche danger is likely to be reduced by tomorrow as slabs become stubborn.

2020-2-19 Printable forecast


Mountain Weather

Yesterday, the passing low favored the southeastern part of the range 7” or more snow falling there, 4” recorded on the summit of Mount Washington and 5” at Hermit Lake. Wind yesterday was from the south in the 50-70 mph range from noon to midnight but was much lighter in the 20-40 mph range at the beginning of the snowfall.

Today, howling winds which shifted from the south to the west around midnight, will shift again to the northwest and increase in speed even more mid-day. Wind is currently blowing near 80 mph with gusts over 100 mph. Continued snow showers and blowing snow will reduce visibility with another inch or so expected to fall. Temperatures are currently cool but will grow much colder, bottoming out at -21F on the summit tomorrow morning. Currently it is 8F on the summit and 30F at Pinkham Notch.

Tomorrow, wind will continue from the northwest and will subside to the 70-90 mph range in the morning, 50’s mph around midday. 

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

The wind speeds that are forecast will eventually pound snow into stubborn, hard wind slabs but not until we pass through a period of peak instability. Wind slabs exist on multiple aspects due to the southerly wind direction followed by a shift to the west and northwest. Blowing snow will make it challenging to identify areas of scouring versus loading. Hollow snow or areas of deep accumulation could fail under your weight.

  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

Snow rangers responded yesterday to a solo hiker in Tuckerman Ravine who sprained his ankle after a night out on Nelson Crag. This person hiked down Right Gully and beneath the Lip of the Tuckerman Ravine headwall. I bring this up because vacation week and Presidents Day weekend brings lots of visitors to the area who may not know the area very well. If you decide to brave the wind today in an attempt to thread the proverbial needle of our avalanche paths, remember that there may be other triggers on slopes above you. The bright and shining red flag signaling avalanche danger today may not be noticed by the unaware. Today isn’t the day to go have a look around and put yourself in the crosshairs of avalanches from above.

Additional Information

The Sherburne and Gulf of Slides ski trails are snow covered with fine riding 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
04/03/20
05:10
4 CM 30.6 MM 37%NC168 CM-1.0 C-0.5 C-1.0 COvercastRain
04/02/20
05:25
Trace 0.1 MMTrace165 CM-0.5 C0.0 C-11.5 COvercastSnow
04/01/20
05:30
0 CM 0.0 MMTrace166 CM-10.5 C6.5 C-11.0 CClearNo precipitationView
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

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 02/19/2020 at 7:05 AM.

Frank Carus, Lead Snow Ranger
USDA Forest Service
White Mountain National Forest