Avalanche Forecast for Sunday, March 1, 2020

This information was published 03/01/2020 at 6:41 AM.
A new forecast will be issued tomorrow.

NOT THE CURRENT FORECAST

This is an archived avalanche forecast and expired on 03/01/2020 at midnight.


The Bottom Line

Evaluate snow and terrain carefully today for the presence of wind slabs, some of which may be reactive to a human trigger and large enough to bury a person. Consider traveling on the firmer, scoured snow to avoid these wind slabs while reducing your exposure to overhead hazards such as other people triggering an avalanche on you. Avalanche danger is MODERATE today. Natural avalanches are unlikely but human triggered avalanches remain possible.

2020-3-1 Printable Forecast


Mountain Weather

Yesterday, upslope snowfall continued off and on through the day ultimately adding another 1.5” to the 2” which fell on Friday. Peak gusts on the summit hit 74mph from the NW though winds were generally moderate most of the day. 

Today, seasonably cold temperatures continue with wind diminishing further. Expect a high just above 0F with NW winds around 30-40mph on the summit. Summit fog and clouds should clear out by midday.

Tomorrow, high pressure will make way for another warm disturbance which may bring some rain to the forecast area. The freeze line is uncertain at this time but some rain seems likely at middle and lower elevations.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

Wind slabs should be on your radar today. Gusty and shifting winds over the past 48 hours have deposited the upslope snowfall in a patchwork of wind slabs over firm, challky snow. These slabs may be large on lee slopes and gullies downwind of a large fetch such as the Headwall of Tuckerman Ravine and across the Gulf of Slides. If you are on a slope over 30 degrees and see cracks shooting ahead in the snow or the snow is over your boot-tops, your risk of triggering a dangerous avalanche has increased substantially.

  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

Low visibility persisted yesterday with few observations from our forecast area though observations from Huntington and Gulf of Slides indicate that a patchwork of soft snow, firm and chalky snow, and some exposed ice crust is the norm. Wind sheltered areas low in east facing bowls provided some soft powder skiing yesterday and likely will today as well. Wind and more snow showers overnight likely refreshed some slopes but also may have made some of the pre-existing slabs thicker and possibly more dangerous. Ease into the terrain and bring a strong partner or partners. We’ve received no observations from the west but loading there seems likely to have occurred during the east winds the blew early in the storm last Thursday.

Additional Information

The Sherburne and Gulf of Slides ski trails are covered with soft snow 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 03/01/2020 at 6:41 AM.

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