Avalanche Forecast for Thursday, January 10, 2019

This forecast was published 01/10/2019 at 7:08 AM.
A new forecast will be issued tomorrow.

NOT THE CURRENT FORECAST

This is an archived avalanche forecast and expired on 01/10/2019 at midnight.


The Bottom Line

Recent avalanche activity, new snow and wind loading are the red flags that continue to highlight avalanche danger today. It’s likely that natural avalanches occurred overnight in the eastern ravines, which if they haven’t slid yet, they may slide today. Slopes and gullies on the eastern half of the compass rose will continue to be stressed by new snow and wind loading today and are rated CONSIDERABLE. Natural avalanches in these areas may be large and run far into low angled terrain. Limit your exposure to these runouts today, even if these slabs appear to be firm and stubborn. Better yet, enjoy the snow in sheltered low angled glades or trails until new snow and wind slabs have settled and bonded. Be wary of wind drifted snow on slabs of ice or in gullies at lower elevations as well.  These areas have a MODERATE danger rating due to the possibility of a human-triggered avalanche.

2019-01-10 Printable PDF

Forecast Area

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Mountain Weather

Around 12” of new snow fell at 3800’ and above yesterday with only slightly less at lower elevations. Initially this storm began with a light easterly wind but as the low passed, the more typical howling northwest wind began, ultimately reaching into the 90’s mph for a three hour period late yesterday afternoon. The wind fell off slowly through the night, reaching the current 55 mph while upslope snow continued, bringing a few more inches to the summits overnight. Another 2-4” is expected to fall today and be driven by strong northwest winds in the 70 mph range. Clouds, fog and blowing snow will reduce visibility through the day. Cold temperatures arrive today as well and will stick around for the weekend with highs in the single digits and lows reaching into the negative teens on Friday night.

Primary Avalanche Problem – Wind Slab

Wind Slab

Aspect/Elevation

Likelihood

Size

Wind slabs will continue to form today and add stress to the slabs built with the 20+” of snow which fell over the past five days. Look for firm, smooth pillows of snow which may be  distributed widely around the terrain due to shifting wind directions and velocity. Recent wind slabs may be stubborn to a human trigger but natural avalanches will continue to be a threat as long as the wind keeps moving snow onto slopes and gullies.

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

There is little doubt that east facing ravines experienced an avalanche cycle last night but the extent of the activity remains to be seen. In question is the depth of the slabs which may have failed. Prior to yesterday’s storm, unreactive wind slabs a meter or more thick were found in many areas of Tucks and Huntington. Observations and stability tests indicated that they were well bonded to the ice crust or the older firm wind slabs beneath but a large, heavy trigger such as a hand charge, which we don’t have, or a new load of snow may be what’s needed to break them loose. Low visibility and elevated avalanche danger won’t allow many of the missing pieces of the ongoing avalanche puzzle to be put in place today, but you can be sure that the puzzle has changed dramatically since yesterday morning.

Additional Concerns

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

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 01/10/2019 at 7:08 AM.

Frank Carus
USDA Forest Service
White Mountain National Forest