Avalanche Forecast for Wednesday, January 23, 2019

This forecast was published 01/23/2019 at 7:10 AM.
A new forecast will be issued tomorrow.


This is an archived avalanche forecast and expired on 01/23/2019 at midnight.

The Bottom Line

Hard, wind slabs built during the extreme wind that followed the MLK weekend winter storm remain a concern today. Settlement and bonding that usually occurs after a snowfall were put on hold as temperatures hovered well below zero. Use normal precautions if you go looking for smooth snow for skiing today. Crampons and an ice axe may be useful on the more wind exposed steep areas near ridgetops. The combination of hard wind slabs, some smaller but softer and possibly more reactive wind slabs, and warming temperatures keep our range-wide rating elevated at MODERATE today. It remains possible for a person to trigger an avalanche on specific terrain features today. Evaluate snow and terrain carefully. Rain on snow conditions tomorrow will likely keep avalanche danger elevated with challenging travel conditions.

2019-1-23 Printable

Forecast Area

Mountain Weather

A frigid air mass moved in after the recent winter storm deposited 13” of increasingly dense snow on the range. That cold air was ushered in on extreme NW wind that raged over 100 mph for close to 12 hours in the early hours of Tuesday morning. After reaching a low of -31F just prior to the wind event, the mercury is continuing its upward journey from Arctic to temperate through the day and into tomorrow. This warm up will bring sleet and freezing rain late this afternoon, with rain later tonight. Some snow showers will fall today but shouldn’t amount to much more than an inch. Temperatures on the summit will climb from the current 10F to 29F by dark to close to 40F tomorrow. Rain tomorrow seems likely to fall all the way to the summit.

Primary Avalanche Problem – Wind Slab

Wind Slab




Winds over 100 mph pounded snow into our primarily east facing terrain. Extreme winds often scour ridgetops while depositing snow and building stubborn slabs lower down the slope, especially beneath steep features and along gully walls. Softer slabs may have formed as wind was slowing so look for more reactive slabs further around the terrain rose. Lower elevation areas weren’t as wind affected but most of the snow was capped by a temperature crust which is likely unreactive.

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

Numerous crown lines were observed during the brief period of clear conditions yesterday afternoon with most avalanche activity likely having occurred Sunday night. Refilled and eroded crown lines indicate that easterly aspects avalanched more than once. Significant scouring occurred in the higher elevation, but small fetch, Huntington Ravine with similar effects likely in other high elevation areas. The upside down nature of the storm made for touchy conditions on Sunday but this wetter layer has refrozen since then and is likely lacking the energy to propagate a crack anywhere. As stated earlier, the biggest concern is the low probability, high consequence hazard of finding and triggering a thin, weak spot in a large wind slab. The human-triggered avalanche in the Lower Snowfields avalanche in 2013 followed similar weather and wind conditions. The MLK weekend storm and more specifically the wind that followed, filled in and developed many of the more ephemeral east and south east facing avalanche paths like the ‘69 slide path on the Summer Lion Head trail.

Additional Concerns

The Sherburne and Gulf of Slides ski trails are snow covered to Pinkham Notch. Several large trees were down yesterday on the Tucks and Sherburne ski trails with wind damage likely elsewhere around the range.

Snow Plot Information

Density (%)HSTTotalAir TT MaxT MinSkyPrecipComments
0 CM 0 MM0CM245 CM-16.0 C-7.0 C-16.0 CClearNo precipitation
3 CM 1.7 MM 9%3CM249 CM-12.0 C-2.0 C-12.0 CBrokenNo precipitation
0 CM 4.0 MM32CM250 CM-10.5 C-5.0 C-13.0 CClearNo precipitationView
38 CM 38.6 MM 12%NC253 CM-5.5 C-2.5 C-5.5 COvercastSnowView
Trace Trace NC213 CM-4.0 C3.0 C-4.0 COvercastSnowView

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
03/25/1911 F-3 F .15 in 1.7 in56.5 MPH86 MPH

270 (W)

03/24/1914 F1 F .21 in 3.4 in74 MPH123 MPH

310 (NW)

03/24/1918 F4 F Trace in 0.1 in63.2 MPH98 MPH

290 (WNW)

03/23/1914 F1 F 0.21 in 3.4 in74.4 MPH123 MPH

310 (NW)

03/22/1924 F12 F 1.09 in 15.2 in38.9 MPH79 MPH

330 (NNW)

03/21/1926 F15 F 0.02 in 0.3 in28.8 MPH60 MPH

160 (SSE)

03/20/1917 F1 F 0.0 in 0.0 in32 MPH58 MPH

270 (W)

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)

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 01/23/2019 at 7:10 AM.

Frank Carus
USDA Forest Service
White Mountain National Forest