|
Your Support Helps
|
|
Snowpack Summary March 24, 2023
Posted by Allen Giernet @ 6:05 am (this summary expires in 24 hours)
This summary applies to backcountry areas only.
The Bottom Line –
Wind Slab avalanches will be possible to human trigger today mainly near and above tree line on Northwest to North to Northeast aspects near ridges and on sides of gullies. The possibility exists for this problem on all aspects. We have received several reports over the past couple of days of both natural and human triggered winds slabs. Look for signs of transported snow, cornices, wind scouring, wind textured snow and pillowed hollow sounding snow to indicate areas of wind loading. Avoid slopes over 30° if you find these indications. Active wind loading will still be likely with moderate to strong West to Southwest winds forecast today and plenty of transportable snow available. Wet slabs may be possible in the San Gabrial mountains on southerly aspects such as the Baldy Bowl today as we expect warmer afternoon temperatures with sunnier skies.
Please share your observations with us at the avalanche center Submit Reports page.
Posted by Allen Giernet @ 6:05 am (this summary expires in 24 hours)
This summary applies to backcountry areas only.
The Bottom Line –
Wind Slab avalanches will be possible to human trigger today mainly near and above tree line on Northwest to North to Northeast aspects near ridges and on sides of gullies. The possibility exists for this problem on all aspects. We have received several reports over the past couple of days of both natural and human triggered winds slabs. Look for signs of transported snow, cornices, wind scouring, wind textured snow and pillowed hollow sounding snow to indicate areas of wind loading. Avoid slopes over 30° if you find these indications. Active wind loading will still be likely with moderate to strong West to Southwest winds forecast today and plenty of transportable snow available. Wet slabs may be possible in the San Gabrial mountains on southerly aspects such as the Baldy Bowl today as we expect warmer afternoon temperatures with sunnier skies.
Please share your observations with us at the avalanche center Submit Reports page.
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.
General Summary
#1 Wind Slab – A number of Wind Slab Avalanches have been reported over the past two days. Both natural and human triggered indicating both, touchy to somewhat stubborn and large in size. Mainly on Northern aspects near to above 8,000’ but possible on other aspects due to topographical influence. Wind Slabs will be found below ridges and on sides of gullies. Expect some bonding as we get warmer temperatures but with significant snow available for transport and moderate to strong winds forecast through the day active loading will still be likely. Reports have indicated a firm icy layer prior to this recent storm that has resulted in poor bonding with significant wind loading through the storm. Look for the signs of wind slab development as you travel. Watch for active wind transport, cornices, scoured areas on windward slopes, wind texture and be aware of pillowed hollow sounding snow as indications of wind slabs or where wind slabs have developed. Stick to lower angle terrain below 30° if you encounter any wind slabs or move to a slope where this problem does not exist.
Weekend Outlook: Clearer skies and some warming will bring slow settling of the snowpack to the recent storm accumulation. Wind slabs may continue to build with moderate winds although overall bonding will happen through the next few days and lower the possibility of triggering. Lower elevation southerly aspects will have the potential for wet loose avalanches mainly in the San Gabriel mountains with warm afternoon temps and solar input through the weekend. Another cold storm is forecast for next week.
Exercise caution if venturing out into the mountains and use avalanche protocols, travel with a partner and bring your beacon, shovel and probe.
Please share any information when you are out in the mountains. Even a photo is helpful. Submit observations to Submit Reports page.
#1 Wind Slab – A number of Wind Slab Avalanches have been reported over the past two days. Both natural and human triggered indicating both, touchy to somewhat stubborn and large in size. Mainly on Northern aspects near to above 8,000’ but possible on other aspects due to topographical influence. Wind Slabs will be found below ridges and on sides of gullies. Expect some bonding as we get warmer temperatures but with significant snow available for transport and moderate to strong winds forecast through the day active loading will still be likely. Reports have indicated a firm icy layer prior to this recent storm that has resulted in poor bonding with significant wind loading through the storm. Look for the signs of wind slab development as you travel. Watch for active wind transport, cornices, scoured areas on windward slopes, wind texture and be aware of pillowed hollow sounding snow as indications of wind slabs or where wind slabs have developed. Stick to lower angle terrain below 30° if you encounter any wind slabs or move to a slope where this problem does not exist.
Weekend Outlook: Clearer skies and some warming will bring slow settling of the snowpack to the recent storm accumulation. Wind slabs may continue to build with moderate winds although overall bonding will happen through the next few days and lower the possibility of triggering. Lower elevation southerly aspects will have the potential for wet loose avalanches mainly in the San Gabriel mountains with warm afternoon temps and solar input through the weekend. Another cold storm is forecast for next week.
Exercise caution if venturing out into the mountains and use avalanche protocols, travel with a partner and bring your beacon, shovel and probe.
Please share any information when you are out in the mountains. Even a photo is helpful. Submit observations to Submit Reports page.
|
General Mountain Weather Forecast |
Weather Page Link
Click on the links below for the latest information
Click here for this Season's Snow Pack Summaries
To better understand the challenges and potential variability over the large area we are producing information for please read our Snowpack Summary - Format and Limitations
Disclaimer:
This Bulletin is designed to generally describe conditions where local variations always occur. Travelers are advised to exercise caution and make slope specific evaluations. As always, please treat this bulletin with appropriately guarded skepticism and make your own assessments. Help to provide more information to the community by reporting your observations
This Bulletin is designed to generally describe conditions where local variations always occur. Travelers are advised to exercise caution and make slope specific evaluations. As always, please treat this bulletin with appropriately guarded skepticism and make your own assessments. Help to provide more information to the community by reporting your observations
Latest Observtions
Click on the observation to go to the full report
|
Observation type
Snowpack Location - Baden Powell Date (yyyymmdd) - 20230323 Comment - Obvs on BP. March 23, 2033. Early morning, 8am, while breaking trail on BP we noticed a poor bonding interface with recent snow from the day before. At 6700’ there was 35cm of new snow over a older, heavy and dense 35cm base. Respective bonding between the old base and new snow did not show any instability and was bonding cohesively. Recent precip came right side up, with the last 15cm of fist dense snow sitting on a interface of graupel. Beneath the weak graupel interface was 20cm of four finger, with a gradual transition to 1 finger snow. CTM 12, SCQ1 at 15cm graupel interface. This grapuel interface showed with the same result at another pit dug at 7800’, CTM 12 SCQ1 at 20cm interface, but did not present itself within the snowpack above this elevation The north face drainage/couloir did have substantial debris from an obvious wet slab avalanche, most likely due to last weeks heavy rain event. R3/D3 with very large swaths of snow that were ripped from canyon walls approx 12’ high and large fields of snow/ice debris that were covered with new snow from day before. I would estimate this slide started at approx 8k and ran the course of the drainage to the bench on highway 2 at 6800’, at a distance of 3/4 of a mile. No other evidence of avalanche or instability was observed. Snow depths as we climbed were as follows.. 6.7k 90cm 7.9k 170cm 8.1k 215cm 8.6k 230cm 9.2k >280cm |
Observation type
Avalanche Location - Wrightwood Date (yyyymmdd) - 20230323 Comment - Spotted a large crown on the upper reaches of Wright Mountain midday Thursday. Most likely a natural slide that occurred in the past 24hrs. Location is at approximately 8450ft on a ~40deg NNE slope. Difficult to assess exact crown height, but given its prominence as viewed from 6100ft and wind-loading prone area, I would estimate >1 meter. Probably a wind slab sliding on a slick, rain saturated melt/freeze later. Did not see any evidence of recent slides in adjacent gullies. |
Observation type
Avalanche Location - Wright Mountain SG Date (yyyymmdd) -20230322 Comment Toured up the acorn trail to the top of the Wright mountain slide path with the intention of gaining more information about the recent snowfall, and hoping for some good turns. There were some signs of localized surface wind slabs on the tour up on the lee of the ridge and other terrain features. I got some small pockets to move in the first 15 cm of the snowpack, but nothing more than a ski length. I observed no other signs of instability other than than the recent loading from the storm. At the top of the north slide path, I saw some cornicing on north east aspects, and was able to drop some chunks of cornice with no result from a few good kicks. I planned to dig a snow pit on the upper section of the bowl to see how the new snow was bonding to the old surface layer. As I stepped down onto the slope, I gave some good hard jumps on a slight convexity at the top. On the 3rd or 4th jump, the entire soft slab of new snow gave way to a D2R3 avalanche that broke at my feet. The crown was approximately 250ft wide and ran 200 vertical feet down to the bench. Observing the crown, I found a slab depth of about 55cm. This consisted of 15cm of wind deposited (4f) on top of 40cm of unconsolidated (fist hard) storm slab. All of this rested on a knife hard rain crust bed surface from our last storm which was quite warm. Apparently the new snow has NOT been bonding well, and will likely need a few warm days to get it to stick. I rode back down the acorn trail ridge and scored some of the best turns I’ve ever had in that area. |
Observation type -
Snowpack Location - Wrightwood Date (yyyymmdd) - 20230322 Comment - Morning tour after the Tuesday system let up, which delivered a decent amount of late season snow. Ascended ridge to approximately 7500'. Snow coverage was good, supportable, and right side up. Cool temps, wind and clouds rolling in kept surface soft and glop-free. Snow turned on again around 1pm, adding a another 3-5cm at 6400ft. Pit summary: 170cm height of snow Fist 170-155 4F 155-138 1F 138-135 (layer where storm warmed up Tuesday AM) 4F 135-127 P 127-124 (melt/freeze crust) 1F 124>ground (saturated rounded grains) CT did not yield any failures, nor did I observe any red flags. The denser spring pow seems to be bonding well with the remnants of the February blizzard and subsequent AR rain storms in this area. However, winds were absolutely howling over the ridgelines throughout the storm, so wind slabs on leeward slopes seem likely at/above treeline. |
General Caution
You should always use safe terrain management and carry avalanche rescue equipment in the backcountry. Most avalanches are triggered by someone in the party or the victim. Practice with your rescue gear often and be prepared should the worst happen. Though we do not have an avalanche forecast center in this area as of yet, the information posted and shared here as well as the resources available on this site will help to make informed decisions for your backcountry travels. Use avalanche forecasts in your travels wherever available and be aware that avalanche ratings are general information. Elevation, location, geographic variability’s, slope aspect and angle all have effects on the particular area you travel in. This is only one piece of the information you should use in your decision making process. There is no substitute for avalanche education, for more resources and information as well as education please refer to our resources page.
You should always use safe terrain management and carry avalanche rescue equipment in the backcountry. Most avalanches are triggered by someone in the party or the victim. Practice with your rescue gear often and be prepared should the worst happen. Though we do not have an avalanche forecast center in this area as of yet, the information posted and shared here as well as the resources available on this site will help to make informed decisions for your backcountry travels. Use avalanche forecasts in your travels wherever available and be aware that avalanche ratings are general information. Elevation, location, geographic variability’s, slope aspect and angle all have effects on the particular area you travel in. This is only one piece of the information you should use in your decision making process. There is no substitute for avalanche education, for more resources and information as well as education please refer to our resources page.
