Avalanche Forecast for Friday, January 11, 2019

This forecast was published 01/11/2019 at 7:14 AM.
A new forecast will be issued tomorrow.

NOT THE CURRENT FORECAST

This is an archived avalanche forecast and expired on 01/11/2019 at midnight.


The Bottom Line

Continued wind loading raises the threat of large natural avalanches in specific east facing areas of the range today. Avalanche danger is teetering between ratings with the potential large size of natural avalanches pushing the rating to CONSIDERABLE in a few areas with the largest wind slabs. Human triggered avalanches remain possible in MODERATE rated areas due to the potential for reactive but smaller wind slabs. Remember that active wind loading can be the heavy trigger needed for a large slab to fail but the weight of a passing skier or climber may also be enough. Cautious route finding will be required to evaluate snow and terrain today.

2019-01-11 Printable

Forecast Area

Mountain Weather

In the past 24 hours, 7.5” of new snow brought our three day total to 21” at higher elevations. Yesterday’s new snow was accompanied by strong winds averaging around 70 mph from the NW. New snow shut off shortly after dark last night but wind slowly increased through the night and is currently blowing in the 80-90 mph range. Wind seems likely to increase further with gusts over 100 mph. Skies may clear but count on blowing snow and passing fog and clouds to create challenging conditions for gathering visual observations. The current summit temperature is -9F and won’t warm much before falling further overnight.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

The strongest wind since Wednesday evening will add more snow load to existing wind slabs today. Confidence is high that these wind slabs will be firm and stubborn in most areas but continued snow loading keeps the threat of large natural avalanches real, particularly in specific areas like the Headwall of Tuckerman Ravine. Other east facing terrain with sufficient fetch downwind could also harbor these large but stubborn wind slabs.

What is a Windslab Avalanche?

  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.

Snowpack and Avalanche Discussion

Three days of snow, wind loading and zero visibility have left us with little direct observation of our avalanche paths. A history of observations of our primary forecast terrain leads us to our current forecast. The strong wind on tap will scour and wind pack some zones while further loading sheltered areas. Continued sluffing will also build wind slabs beneath steep features like the approach to Pinnacle, the big ice slab in Odell and below chokepoints in the Chute. Both loading conditions will occur in the Headwall area of Tuckerman Ravine.

Additional Concerns

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

Snow Plot Information

DateHN24HN24W
(SWE)
Density (%)HSTTotalAir TT MaxT MinSkyPrecipComments
03/20/19
05:28
0 CM 0 MM0CM214 CM-11.0 C-4.5 C-14.0 CClearNo precipitation
03/19/19
05:25
0 CM 0.0 MMNC215 CM-13.0 C-9.5 C-15.0 CFewNo precipitation
03/18/19
05:20
Trace 0.1 MMNC216 CM-15.5 C-13.0 C-15.5 CBrokenSnowView
03/17/19
05:26
4 CM 3.7 MM 9%4CM218 CM-14.5 C-2.5 C-15.0 CBrokenNo precipitation
03/16/19
05:22
0 CMTrace 0CM215 CM-2.5 C8.5 C-2.5 CBrokenNo precipitationView

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
03/19/194 F-4 FTrace Trace 43.4 MPH63 MPH

300 (WNW)

03/18/193 F-6 F 0.03 in 0 in52.1 MPH82 MPH

280 (W)

03/17/192 F-6 F 0.07 in .5 in61.5 MPH110 MPH

270 (W)

03/16/1925 F2 F 0.24 in 2.3 in67.5 MPH97 MPH

280 (W)

03/15/1941 F25 F 0.04 inTrace 54 MPH105 MPH

250 (WSW)

03/14/1940 F17 F Trace in Trace in27.7 MPH75 MPH

200 (SSW)

View
03/13/1924 F11 F .07 in .8 in29 MPH52 MPH

290 (WNW)

03/12/1911 F-1 F 0.14 in 1.9 in65 MPH104 MPH

280 (W)

03/11/1917 F6 F 0.35 in 4.4 in77 MPH114 MPH

280 (W)

03/10/1925 F4 F .35 in 3.7 in47.2 MPH94 MPH

150 (SSE)

View
03/09/1919 F0 F 0 in 0 in36.1 MPH70 MPH

290 (WNW)

03/08/199 F-12 F 0 in 0 in49.5 MPH74 MPH

300 (WNW)

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 01/11/2019 at 7:14 AM.

Frank Carus
USDA Forest Service
White Mountain National Forest