Avalanche Forecast for Wednesday, April 15, 2020

This information was published 04/15/2020 at 6:40 AM.
A new forecast will be issued tomorrow.

NOT THE CURRENT FORECAST

This is an archived avalanche forecast and expired on 04/15/2020 at midnight.


The Bottom Line

Today, the freezing elevation mark exists at mid elevation. The summit and upper portions of the ravines are likely to have received enough time to re-freeze and create conditions that could be a catalyst for a long sliding fall. Lower in elevation, snow is likely to remain wet and difficult to travel through without floatation. While in avalanche terrain a checkerboard of softer wet snow and hard refrozen surface may exist. The impact of solar gain is uncertain today, if clouds part and the sun begins to heat the snow surface it could decrease surface stability. Wet loose avalanches are unlikely in isolated terrain but worth keeping on your radar. The avalanche danger is rated LOW today.

A plethora of travel conditions exist today. Ice axe, crampons and snowshoes or skis will ease travel in certain locations with warm snow of breakable crust. Although unlikely, a person may be able to trigger a small point release in small isolated pockets.


Mountain Weather

Yesterday, temperatures dipped below the freezing mark for the first time after Monday’s rain event. Temperatures at the summit were in the high teens and a high of 39F was recorded at Harvard Cabin. Wind speed gradually decreased from nearly 90 mph in the morning to the 30 mph at nightfall. Overnight the OBS recorded trace amounts of snowfall.

Today,  summit temperatures will be in the low teens while on and off again clouds create uncertainty on how much solar gain will impact today. Wind will be from the W between 30-45mph, gusts may reach up to 60mph.

Tomorrow, similar weather conditions will continue. Temperatures in the low teens, increasingly cloudy skies and a NW wind between 35-50mph.

Primary Avalanche Problem – Wet Loose

Wet Loose

Aspect/Elevation

Likelihood

Size

Wet loose avalanches are unlikely today in mid elevation terrain. Rain has loosened bonds in the snowpack and at some elevations freezing temperatures have not been consistent enough to refreeze the snow surface. Small avalanches in isolated terrain today may be able to push you off course into undesirable terrain.

  Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

Forecast Discussion

Today, the freezing elevation lies somewhere between the bottom of the ravines and the summit. Uncertainty lies in how much heat from the rainfall still exists in the snowpack and how much solar gain we receive today. If you find yourself in the mountains today, come prepared with gear to mitigate the hazards of a long sliding fall and flotation to combat the difficulties of post holing on the approach.

Additional Information

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

The Lion Head Winter Route remains the easiest route to the summit from Pinkham Notch but requires an ice axe, crampons (not just micro-spikes) and possibly a rope. This is a mountaineering route and requires solid skills for a safe, timely ascent.

Details on daily snowfall totals, precipitation type, total depth of snow and other information can be found on our page devoted to snow study plot data. Click here to check it out.

Snow Plot Information

DateHN24HN24W
(SWE)
Density (%)HSTTotalAir TT MaxT MinSkyPrecipComments
04/13/20
06:15
0 CM 0.1 MM0CM206 CM-3.5 C7.5 C-7.0 COvercastRain
04/12/20
06:20
Trace 1.8 MMTrace216 CM-7.0 C-4.0 C-7.0 CFewNo precipitation
04/11/20
06:20
14 CM 23.1 MM 14%62CM222 CM-8.0 C-6.0 C-8.0 COvercastNo precipitation
04/10/20
06:30
53 CM 49.5 MM 12%NC200 CM-6.0 C-2.0 C-6.5 COvercastSnowView
04/09/20
06:25
0 CM 0.0 MM0CM158 CM-1.0 C8.0 C-4.5 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
05/25/2054 F46 F 0.0 in 0.0 in18.7 MPH44 MPH

260 (W)

05/24/2054 F40 F 8.3 in 21 in8.3 MPH21 MPH

280 (W)

05/23/2055 F43 F 0.0 in 0.0 in15 MPH45 MPH

300 (WNW)

05/22/2055 F40 F 0.0 in 0.0 in37.4 MPH67 MPH

290 (WNW)

05/21/2053 F38 F 0.0 in 0.0 in29.4 MPH59 MPH

280 (W)

05/20/2050 F34 F 0.0 in 0.0 in29.4 MPH59 MPH

280 (W)

05/19/2041 F27 F 0.0 in 0.0 in15.3 MPH36 MPH

100 (E)

05/19/2050 F34 F 0.0 in 0.0 in11.4 MPH25 MPH

30 (NNE)

05/18/2045 F30 F 0.0 in 0.0 in14.7 MPH36 MPH

70 (ENE)

05/17/2040 F30 F 0.0 in 0.0 in17 MPH35 MPH

270 (W)

05/16/2037 F28 F .16 in 0.0 in38.8 MPH101 MPH

310 (NW)

05/15/2042 F32 F .95 inTrace 31.5 MPH95 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 04/15/2020 at 6:40 AM.

Joe Soccio
USDA Forest Service
White Mountain National Forest