Avalanche Forecast for Monday, December 24, 2018

This forecast was published 12/24/2018 at 6:52 AM.
A new forecast will be issued tomorrow.

NOT THE CURRENT FORECAST

This is an archived avalanche forecast and expired on 12/24/2018 at midnight.


The Bottom Line

Pockets of small wind slab that a human could trigger can be avoided by travelling on our widespread refrozen snow surface. All forecast areas have LOW avalanche danger. The hard, slick, refrozen snow present in our steep terrain makes long sliding falls a significant hazard today. Crampons, an ice axe, and your ability to use them effectively to avoid a fall are crucial for safe travel in the alpine. On our ice climbs, continue to be mindful of possible ice dams, or flowing water building pressure beneath recently frozen ice that could break with the placement of a tool or crampon.

2018-12-24_Printable_PDF

Forecast Area

Mountain Weather

Clear skies and temperatures in the teens F yesterday have given way to a weak low pressure system that is bringing cloud cover to the Presidential range. Clouds should persist all day, though we may see a few breaks this afternoon. Minimal to no precipitation is forecast as temperatures remain within a few degrees of the current 11F on the summit. Current summit wind is 25 mph from the W and may increase slightly while holding this general direction. For those planning to get into our mountains on Christmas, expect similar temperatures and slightly stronger wind than today under clear skies.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

Isolated wind slabs exist in the terrain and can generally be found on the eastern half of the compass rose. Formed Saturday night and into Sunday morning, these new pockets should range from stubborn to reactive to a human trigger. Plenty of opportunities exist to avoid these isolated slabs on our larger slopes, but it’s possible that our narrowest gullies could hold sections of wall to wall wind slab.

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

The 3” of rain and sustained above freezing temperatures last week were followed by the current cold temperatures that have solidly refrozen our snowpack. The Lip in Tuckerman Ravine produced a large wet slab avalanche sometime during the rain storm, possibly late Friday or early Saturday. Our refrozen hard snow surface is actually quite smooth in many areas. The minimal new snow Saturday had enough ability to stick to the older snow to make most of our snow surfaces bright white in appearance, but recently formed wind slabs are the exception rather than the rule.

Additional Concerns

The Sherburne and Gulf of Slides ski trails are mostly snow covered to Pinkham Notch, but expect melted out areas to provide challenging conditions.

Snow Plot Information

DateHN24HN24W
(SWE)
Density (%)HSTTotalAir TT MaxT MinSkyPrecipComments
03/22/19
05:20
Trace Trace NC213 CM-4.0 C3.0 C-4.0 COvercastSnowView
03/21/19
05:23
0 CM 0 MM0CM213 CM-1.5 C0.0 C-11.5 COvercastNo precipitation
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

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
03/20/1917 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)

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)

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 12/24/2018 at 6:52 AM.

Ryan Matz, Snow Ranger
USDA Forest Service
White Mountain National Forest