Avalanche Forecast for Thursday, February 7, 2019

This forecast was published 02/07/2019 at 7:00 AM.
A new forecast will be issued tomorrow.

The Mount Washington Avalanche Center will no longer issue daily avalanche forecasts for the 2018/19 season. Read more

The Mount Washington Avalanche Center will no longer issue daily avalanche forecasts for the 2018/19 season. Instead, we will post an updated General Bulletin as needed, in case of significant snow or weather events that might vary from the typical daily changes that come with spring weather. We will also keep you informed about the official closure of the portion of the Tuckerman Ravine Trail from Lunch Rocks through the Lip and Headwall as well as the switch from the Lion Head Winter Route to the summer trail. Observations from the field will continue to be a valuable resource, so please keep submitting photos, videos and observations here and we will do the same. Check the Forecast page for update on Sherburne Trail closures, which are imminent as spring snowmelt continues.

The switch to a General Bulletin does NOT mean that the mountains are now a safe place to ski. The hazards which emerge in the spring are significant and require careful assessment and strategic management. If you have never skied Tuckerman, peruse our Incidents and Accidents page for spring related incidents involving avalanches, long sliding falls, icefall, crevasse and moat falls, and other incidents related to diurnal changes in the snowpack. These will help you understand and plan for these hazards.


The Bottom Line

A mixed bag of hazards will face anyone heading into the mountains today. On the list of concerns are a refrozen, long-sliding-fall type of snow surface, new sleet and freezing rain, and temperatures hovering around freezing. To top it off, fog will reduce visibility up high. New precipitation and warm temperatures keep some concern for wet slab avalanches on the radar. Wet slab and loose wet avalanches are unlikely today, though warmer than forecast conditions could increase the potential a bit. You’ll find microspikes really helpful today on area trails, with crampons, ice axe and a strong ability to stay on your feet necessary for safe travel in steeper terrain. LOW avalanche danger will exist at all elevations and aspects today.

2019-2-7 Printable

Danger Rating by Zone

Mountain Weather

Yesterday, sunny skies and warm temperatures prevailed until mid-afternoon allowing a few folks to enjoy an early corn harvest. Snow only softened on sunny aspects at mid and upper elevations as temperatures reached only to around 30F on the summit. Last night temperatures dipped to 23F as clouds and another round of mixed, but mostly frozen, precipitation fell last night. At this time, it looks like half an inch of snow fell on the summit and the rest was sleet, totaling .24” liquid. Today will bring a mixed bag of sleet and freezing rain and possibly snow, though only a trace amount is expected. A high of 33F on the summit along with light winds from the W then SW at 25-40 mph then 10-25 mph. Summit fog and clouds will hamper visibility through the day. Rain returns tonight before cold weather returns Friday with some snow and high winds.

Primary Avalanche Problem – Wet Slab

Wet Slab

Aspect/Elevation

Likelihood

Size

If you have to pick an avalanche problem today, wet slabs would be the closest fit. Temperatures rising above freezing will keep this on the list of hazards but the potential for long-sliding-falls is jockeying for first place on the list. The largest and steepest slopes carry the greatest potential for a larger, though still unlikely, avalanche in what have proven to be unreactive surface slabs.

What is a Wet Slab Avalanche?

  Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.

Snowpack and Avalanche Discussion

Someone threw the brakes on the snow train after the mountain received 60” of snow during the month of January. Average for the month is 44”, with 40” average in February. So far, one week into the new month, we’ve received just 2.8” of snow. Though the sun tracked across the sky in a winter-like trajectory yesterday, sunshine and warm temperatures allowed some softening on sunny aspects. Signs of the recent warm-up were everywhere with glide cracks beginning to open and tracks on the surface from falling ice in the Headwall. While some dry snow existed deep in the snow, it was beneath a thick ice crust in the limited number of areas that we dug in Tuckerman and Huntington Ravine. While we aren’t fully isothermal yet, given the refrozen surface and stout crusts deep in the snowpack, our avalanche problems would require significant amounts of rain or meltwater to raise concerns.

Avalanche Safety Information Study

Please contribute to the effort to improve backcountry avalanche forecasts! Researchers in Canada devised a study to better understand how we communicate the avalanche risk, and we need your help. Please fill out this survey. It will take a few minutes, but it will help us as we work on new ways to give you the most important avalanche information.

Snow Plot Information

DateHN24HN24W
(SWE)
Density (%)HSTTotalAir TT MaxT MinSkyPrecipComments
05/22/19
05:25
Trace 6.2 MMTrace60 CM0.5 C2.0 C-1.0 CClearNo precipitationView
05/21/19
05:25
0 CM 4.2 MM0CM60 CM2.0 C15.0 C2.0 COvercastNo precipitation
05/20/19
05:30
0 CM 20.4 MM0CM68 CM11.0 C12.0 C3.5 CObscuredNo precipitation
05/19/19
05:25
0 CM 0.0 MM0CM72 CM4.0 C6.0 C2.0 COvercastNo precipitation
05/18/19
05:20
0 CM 7.6 MM0CM80 CM1.0 C6.0 C1.0 COvercastNo precipitation

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
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)

05/18/1934 F26 F 0.06 in 0.5 in39 MPH74 MPH

300 (WNW)

05/17/1940 F28 F .22 in .05 in37 MPH81 MPH

300 (WNW)

05/16/1932 F25 F .03 in 04 in22.8 MPH40 MPH

310 (NW)

05/15/1926 F20 F .05 in .4 in32.1 MPH67 MPH

330 (NNW)

05/14/1928 F17 F .2 in 2 in19.1 MPH57 MPH

100 (E)

05/13/1928 F19 F .07 in 0.9 in34.6 MPH67 MPH

100 (E)

05/12/1931 F17 F 0 in 0 in20.5 MPH47 MPH

330 (NNW)

05/11/1932 F18 F .1 in 0 in53.6 MPH84 MPH

300 (WNW)

05/10/1944 F27 F .85 in 0 in50.1 MPH88 MPH

220 (SW)

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 02/07/2019 at 7:00 AM.

Frank Carus
USDA Forest Service
White Mountain National Forest