Avalanche Forecast for Thursday, January 17, 2019

This forecast was published 01/17/2019 at 7:03 AM.
A new forecast will be issued tomorrow.

NOT THE CURRENT FORECAST

This is an archived avalanche forecast and expired on 01/17/2019 at midnight.


The Bottom Line

Wind slabs in steep terrain should remain on your radar today. Older, stubborn and large slabs plus newer but smaller wind slabs are the main avalanche concern and earn a LOW danger rating. Both wind slabs are stubborn to a human trigger, but some exceptions may exist in the form of softer pockets. All of these slabs are resting on a smooth ice crust on which the last avalanche cycle occurred. If you brave the frigid and windy weather, bring your avalanche rescue gear along with crampons and an ice axe.

2019-1-17 Printable

Forecast Area

Avalanche Safety Information Study

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Mountain Weather

An arctic clipper brought an inch and a half of snow to higher terrain yesterday, with west wind averaging 60 mph and gusting to 108 mph. The temperature dropped 25 degrees in the past 24 hours to a brisk -17F. The mercury will rise to, but fall short of, the 0F mark with wind remaining in the 55-70 mph range under clear skies through the daylight hours. No snow is forecast today, though more snow may fall late tonight with more tomorrow which may bring 1-3” total.  

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

Wind slab that formed on January 10th and 11th remain a concern, primarily due to the icy bed surface that they are resting on. Though it would be unlikely for a person to trigger one of these slabs, the resulting avalanche could be large. Isolated pockets of wind slab formed yesterday due to new snow and a strong west wind. Areas in the Gulf of Slides and the Headwall of Tuckerman Ravine are most likely to contain the greatest concentration of this wind slab. These will be mostly firm and stubborn to trigger.

  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

Cold, clear conditions and a strong ice crust from Dec 23rd should keep you thinking about low probability and high consequence hard slab avalanches if you brave the cold weather and head into steep, high elevation terrain today. Triggering any type of firm slab that we grow so readily here usually takes some bad luck to find the thin spot in the slab. Stability tests of this type of avalanche problem generally show moderate strength weak layers but little propagation potential. Continue to dig but remember to limit your exposure to the risk by managing your terrain, moving one at a time and carrying your avalanche rescue gear. As we move forward in the season, realize that all our main avalanche paths are now fully developed with around 5’ of snow on the ground and multiple avalanche cycles filling in our paths.

Additional Concerns

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

Come to a free avalanche awareness presentation at the LL Bean store in Freeport tonight, 7-8:30pm. Frank will be presenting a Know Before You Go program followed by information on the new forecast area with time for a Q&A session.

Snow Plot Information

DateHN24HN24W
(SWE)
Density (%)HSTTotalAir TT MaxT MinSkyPrecipComments
05/31/19
05:20
0 CMTrace 0CM0 CM8.0 C11.0 C0.5 CBrokenNo precipitation
05/30/19
05:25
0 CM 0.0 MM0CM0 CM7.5 C7.5 C1.0 CScatteredNo precipitation
05/29/19
05:25
0 CM 22.3 MM0CM0 CM1.5 C4.0 C0.0 COvercastNo precipitation
05/28/19
05:25
0 CM 0.0 MM0CM0 CM0.5 C11.0 C0.5 CClearNo precipitation
05/27/19
05:15
0 CM 0.0 MM0CM10 CM8.0 C15.5 C8.0 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
05/30/1946 F36 F 0 in 0 in27.9 MPH55 MPH

290 (WNW)

05/29/1947 F33 F 0 in 0 in20 MPH48 MPH

290 (WNW)

05/28/1934 F28 F .71 in 3.7 in20 MPH48 MPH

290 (WNW)

05/27/1940 F27 FTrace 0 in38.9 MPH68 MPH

300 (WNW)

05/26/1948 F39 F .77 in 0 in48.7 MPH75 MPH

290 (WNW)

05/25/1947 F31 F .42 in 0 in17.7 MPH63 MPH

240 (WSW)

05/24/1942 F32 F .66 in 0 in44.8 MPH105 MPH

05/23/1944 F30 F .16 in 0 in26.8 MPH71 MPH

270 (W)

05/22/1934 F21 F 0 in 0 in36.2 MPH115 MPH

330 (NNW)

05/21/1934 F23 F .57 in 1.9 in73 MPH135 MPH

330 (NNW)

05/20/1951 F33 F 0.57 in 0.0 in48 MPH82 MPH

250 (WSW)

05/19/1951 F34 F .6 in 0 in34.2 MPH66 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 01/17/2019 at 7:03 AM.

Frank Carus
USDA Forest Service
White Mountain National Forest