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

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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
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 12/24/2018 at 6:52 AM.

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