Avalanche Forecast for Friday, January 18, 2019

This forecast was published 01/18/2019 at 7:06 AM.
A new forecast will be issued tomorrow.

NOT THE CURRENT FORECAST

This is an archived avalanche forecast and expired on 01/18/2019 at midnight.


The Bottom Line

The recipe for small wind slabs is on the table today with a ripe wind direction and speed for loading. However, it’s likely we will lack the snow which serves as the crucial ingredient, at least during daylight hours, to build those slabs. If you are out climbing (recommended) or skiing (not so much) bring your crampons for the rugged, hard snow and keep an eye on the weather, especially later in the day. Overall stable conditions today, even with a small amount of new snow, should keep us at a LOW danger rating today. If we receive the upper end of the forecasted 1-3” of snow, the potential for small, human-triggered avalanches may exceed that rating, especially as evening approaches.

2019-1-18 Printable

Forecast Area

Mountain Weather

Low tide conditions continue with no new snow recorded in the past 24 hours around the range. Summit temperature at 6 am is 0F with wind from the southwest near 40 mph. A weak cold front will pass through this afternoon and bring snow shower activity with it. Accumulations should be light, with forecasts ranging from one inch up to three inches. Wind will shift west and ramp up into the 45-60 mph range in the afternoon. Dry air in place and limited moisture in the system seem likely to keep snow accumulations low. Temperatures will fall again tonight to near -10F with wind remaining from the northwest in the 40-55 mph range. After a fairly calm but seasonably cold day tomorrow, a significant winter storm arrives in the evening with temperatures staying quite cold through the storm. Low density snow will likely create challenging conditions for a number of reasons with “postholing” through thigh-deep snow, even with snowshoes, being among them.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

Wind slabs have been unreactive for several days now bringing generally safe avalanche conditions to the range. Some pockets of softer snow exist but also seem to present generally stable conditions. The possibility of finding and triggering a thin spot in a hard wind slab resting on the ice crust is unlikely but not impossible. New wind slabs could develop late in the day, especially if we receive 3” of new snow.

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

Remnants of the 1.5” of snow that fell Wednesday and developed small but softer wind slabs are scattered around in the most sheltered locations of the terrain. Overall, the snow surface in avalanche paths is dominated by thick hard wind slabs or avalanche debris from the widespread January 10/11 avalanche cycle. Facets have been observed around the ice crust under the hard wind slabs that remain, though triggering these tough slabs remains unlikely. The incoming snowstorm will be greeted by fully developed avalanche paths, at least in the eastern half of the compass rose. This includes slopes and gullies with a more south-easterly aspect.

Additional Concerns

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

Thanks to the 72 people that came out to LL Bean in Freeport for the avalanche awareness talk last night. We’ll see you there next year. Check our events page for two more talks coming up at REI stores in Reading and Boston.

Snow Plot Information

DateHN24HN24W
(SWE)
Density (%)HSTTotalAir TT MaxT MinSkyPrecipComments
03/26/19
05:30
0 CM 0 MM0CM245 CM-16.0 C-7.0 C-16.0 CClearNo precipitation
03/25/19
05:20
3 CM 1.7 MM 9%3CM249 CM-12.0 C-2.0 C-12.0 CBrokenNo precipitation
03/24/19
05:19
0 CM 4.0 MM32CM250 CM-10.5 C-5.0 C-13.0 CClearNo precipitationView
03/23/19
05:17
38 CM 38.6 MM 12%NC253 CM-5.5 C-2.5 C-5.5 COvercastSnowView
03/22/19
05:20
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)

View
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 01/18/2019 at 7:06 AM.

Frank Carus
USDA Forest Service
White Mountain National Forest