This information is a Conditions Update. Danger ratings are only issued with avalanches advisories. The next avalanche advisory is scheduled for Saturday March 16, 2019.
Previous avalanche advisories HERE
MIDWEEK SNOW AND AVALANCHE CONDITIONS SUMMARY
Moderate to strong E to ESE winds yesterday afternoon and overnight have picked up 6-9" of low density snow that fell Monday March 11th and transported it to leeward aspects forming fresh wind slabs 6" to 16" thick. Human-triggered wind slab avalanches will be likely and natural avalanches will be possible in leeward and cross-loaded terrain, on predominantly W to N aspects, in mid and upper elevations. It may be possible, but is generally unlikely, for a wind slab avalanche to step down to buried persistent weak layers, triggering an avalanche up to 2' thick at mid and upper elevations. Human-triggered avalanches will be unlikely at lower elevations. Careful snowpack evaluation, cautious route-finding, and conservative decision-making will be essential while we give the snowpack time to adjust to the new load.
Numerous human-triggered avalanches occurred on Tuesday March 12, including:
Several natural loose dry and wet loose avalanches were observed Tuesday March 12 across Hatcher Pass.
Hatcher Pass received 4" new snow (0.24" SWE) over the weekend, another 9" snow (0.6") SWE Monday March 11th, and trace snow Tuesday March 12th overnight. The 4" of snow falling over the weekend fell during moderate to strong winds. The 9" of low-density snow that fell Monday March 11th blanketed the landscape nicely, falling under light gusting to moderate winds. This low density snow has since been redistributed across Hatcher Pass due to E to ESE moderate to strong winds overnight.
This report is a mid-week conditions update, so please be sure to check hpavalanche.org for advisories on Saturdays and follow the HPAC Facebook for updates. Help us keep tabs on the Hatcher Pass area! If you see any avalanche activity send us an observation HERE. Thank you to everyone who has already submitted observations this season - you can see those HERE!
Above: 9" new low-density snow fell with light winds Monday the 11th. Since then moderate to strong E>ESE winds have picked up much of this new snow and transported to W to N aspects, forming fresh wind slabs.
Problem 1: Wind Slab
East and Southeast winds gusting moderate to strong yesterday afternoon and overnight have formed fresh wind slabs 6-16" thick in leeward and cross-loaded terrain, on predominantly W to N aspects. Southeast winds are expected to continue at 20-30 mph at ridgetops throughout today, which will continue to transport snow. Human-triggered wind slab avalanches will be likely and natural wind slabs will be possible on W to N aspects, in mid and upper elevations. These avalanches could be large enough to bury, injure, or kill a person.
Pole tests will easily reveal stiffer snow sitting over weaker snow and will be a good indicator for the presence of wind slabs and slab thickness.
Above: Moderate to strong E to ESE winds Wednesday afternoon and night have built wind slabs 6" to 16" deep on leeward W to N aspects.
Problem 2: Persistent Slab
It will be generally unlikely, but may be possible, to trigger an avalanche on deeper, buried persistent weak layers, SW to NE aspects, in mid to upper elevations, on slopes steeper than 35 degrees. Small avalanches in isolated areas or extreme terrain. These avalanches may be up to 2' thick and large enough to bury, injure, or kill a person.
Additional Concern: Cornices
13" new snow and moderate to strong winds this week have built large cornices that have proven sensitive to trigger. Give cornices a wide berth as they can break back much further back then they appear and cornices can trigger larger avalanches below.
Above: New snow and moderate to strong winds over the last week have built large cornices. Pictured here are large cornices above Rae Wallace Chutes.
The last human-triggered avalanches occurred Tuesday March 12th. These included several small and large storm slab avalanches, wind slabs, loose dry avalanches, two cornice triggered avalanches, and a wet loose avalanche. The last natural avalanches observed occurred Tuesday March 12th, including several long running wet loose and loose dry avalanches on slopes steeper than 40 degrees. There were also several human-triggered and natural wind slab avalanches reported during the wind event on March 9 and 10 including a large wind slab human-triggered avalanche on a N aspect of Hatch Peak above $1000 run reported March 10.
Above: 2 larger (D1.5 to D2) slab avalanches, 3500', estimated 6-12" deep on NW aspect of Arkose (Punk Spines, due N of Stairstep), one of which looked to have sympathetically triggered another small slab avalanche below.
Above: Several small (D1) soft storm slab avalanches, 4500', 6-12 inches deep, on steep SW to W aspects of spines of Rae Wallace Chutes
Above: Cornice-triggered loose dry avalanche on SW aspect of Marmot at 4300'.
Above: Cornices have grown quite large along Marmot ridgeline and were sensitive to trigger on March 12. This cornice was easily triggered resulting in a long running loose dry avalanche on the SW aspect of Marmot at 4300'.
Above: Numerous long-running dry loose natural avalanches off steep (>40 degrees) S aspect of Microdot at 4600'.
Above: Long running loose dry avalanche on NE/E aspect of Skyscraper, 4500', that ran from ridge into Eldorado Bowl about 700 ft.
Above: 100' wide propagating human-triggered small (D1) wind slab avalanche on NE aspect of Lower Eldorado Bowl test slope at 3200'. 6-16" deep soft slab. Observed on March 9th during wind event.
Above: Natural wind slab avalanches in NE aspect of cross-loaded Martin Mine Gully at 4000' that is believed to have occurred overnight on March 8 during the wind event.
Above:Wind slab in W side of Hatcher Pass at 3900' reported on March 9 during wind event.
Above: Natural wind slab that stepped down into buried persistent weak layers and failed at the ground in April Bowl at 4500' on W aspect. Reported on March 10 during the wind event. This path is a repeat offender and has avalanched many times this season.
Weather at 3450' since Saturday 3/9:
Temperatures averaged 26°F, with a low of 13°F and a high of 3°F.
Winds averaged S 4 mph, max 13 mph. Max gusts recorded were S 30 mph .
There has been 13" new snow recorded at Independence Mine since 3/9.
Weather at 4500' since Saturday 3/9:
Temperatures averaged 19°F, with a low of 10°F and a high of 23°F.
Winds averaged ESE 11 mph, max 24 mph. Gusts averaged ESE 18 mph, max gust 39 mph.
Stay tuned to the NOAA point forecast for an updated weather forecast each day. The best way to see if it's snowing in Hatcher Pass is to look at the webcam snow stake HERE and the Independence Mine SNOTEL site HERE
State Parks Snow Report and Motorized Access information can be found here.
Get the full HPAC summary HERE for Thursday, March 14, 2019.
Forgot your password?
Lost your password? Please enter your email address. You will receive mail with link to set new password.
Back to login