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Avalanche Advisory for 2016-01-12 06:51:32
- EXPIRED ON January 13, 2016 @ 6:51 amPublished on January 12, 2016 @ 6:51 am
- Issued by Nick Meyers - Shasta-Trinity National Forest
Bottom Line
LOW avalanche danger exists for all elevations and aspects this morning. The avalanche danger will increase later today as a wet and windy storm moves into the forecast area. A high wind warning is in effect from 10am this morning to 7am PST Wednesday. Up to 1.60" of precipitation is expected, translating into several feet of new snow above 7,000 feet. Wind/storm slab avalanche danger will rise to CONSIDERABLE/HIGH danger during and/or immediately after the storm.
Avalanche Problem 1: Wind Slab
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Wind slabs are far and few between this morning, however NEW winds slabs will form today and increasing danger will ensue. A good looking winter storm will move over the area bringing heavy precipitation and very strong southwesterly winds. Small to large wind slabs will form on leeward W-NW-N-NE-E facing slopes. Strong winds have the ability to load non-typical areas such as mid-slope starting zones. All terrain, near and above treeline, should be considered dangerous during this storm. One would likely not be able to see, let alone stand up anyways. It's immediately after the storm when skiers and riders venture above treeline and wind slabs could remain sensitive. Unsupported snow slopes above cliffs, wind loaded steep couloirs and other complex or extreme terrain will represent the best places to find sensitive wind slabs.
Avalanche Problem 2: Loose Dry
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Small surface sloughs triggered off ski cuts/turns could still be possible today due to some lingering light density snow that still sits on protected, northerly aspects. Slopes steeper than 37 degrees near and slightly above treeline will be the best places to trigger loose sloughs. It is possible for sloughs to trigger minor soft slabs which could break over a wider area where light wind has created soft slab properties. Remember, a slab only needs to be slightly stronger and more cohesive than the weak layer or less dense snow under it to cause a slab avalanche. Sloughs, while usually harmless, can certainly sweep a rider off their feet and into terrain traps, into a tree, over a cliff, etc.
Forecast Discussion
Batten the hatches, a windy storm is already at the coast this morning and will kick off a very active pattern to remain through the rest of the week. For this first front, 700mb southwest winds will crescendo across the entire region, nearing 80 knots over the Cascades this afternoon and this evening. Precipitation amounts over the next two days are forecasted to be near 1.60 inches of water. We've seen a warming trend with temperatures lately and this will start us off with a 5,500 to 6,000 foot snow level for the beginning of the storm, today and tonight. Wednesday temps will begin to drop as will the snow level, 4,800 feet Wednesday and 4,600 feet Wednesday night. Thursday, snow levels should drop to town. The mountain and forecast area west of I-5 will certainly get some snow, and a lot of it. We could see 1-2 feet of new snow near and above treeline by close of business Wednesday. Most notably with this storm system will be the wind. A high wind warning is in effect from 10am this morning to 7am PST Wednesday. Extreme winds above treeline are expected into Wednesday morning. South/Southwest in direction, 6,000 foot winds will blow 20-30 mph today, increasing to 40 mph tonight. Mid-mountain (10,000 ft) winds will blow 60-70 mph with gusts higher. Upper mountain winds will blow 70-80 mph with gusts to 90+.
THIS SEASON PRECIPITATION: Since October 1st (the wet season), we have received 11.94 inches of water, normal is 17.85 inches, putting us at 66% of normal. For the month of January and year of 2016 we've received 2.45 inches of water, normal is 2.64 inches, putting us at 92% of normal
Recent Observations
Several degrees of warming yesterday created for some mashed potatoe snow conditions for lower elevations. A sun crust formed in open, southerly aspects from the day prior creating somewhat challenging skiing in areas. However, southerly aspects in the shaded trees was better, though you had to watch out for firm, compacted snow around the base of trees where "tree bombs" have fallen. Northerly aspects are still holding good snow. One might be able to trigger more loose slough/point release avalanches only on steep, cold, shaded north slopes near and slightly above treeline where dry snow has preserved.
Instabilities in the snowpack have been few and no new observations were reported yesterday. Overall, the snow has consolidated about 2 inches over the forecast area and our right side up snowpack has been showing good stability. Loose sloughs and roller ball activity will be put on hold for now and we currently are most focused on the storm that sits on deck. This storm will certainly raised the avalanche danger and put wind and storm slabs as the top avalanche problems. We don't forsee any existing weak layers as problems for the additional weight of the new snow. Moreover, heavy precipitation rates with very windy conditions will create new, potentially large wind and storm slabs in the coming days.
Below: Pits and photos from recent days
Pits from the west side of the forecast area.
Cliff Lake area, 1.11.16
Castle Lake area, north facing, 1.11.16
Avalanche Gulch, 1.11.16 Photo: Rathbun
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LOCAL AREA ROAD, NORDIC and SNOWMOBILE PARK STATUS:
The Sand Flat cross country ski trails are in great shape and ready for your cross country skis or snow shoes. These are backcountry trails marked with blue diamonds on trees. Trails are not groomed. Snow shoers, please blaze a parallel trail to cross country skiers staying out of the skin track. These trails can be accessed via the Everitt Memorial Highway. Thank you, and enjoy!
The Mt Shasta Nordic Center is open! These beautiful, groomed trails can be accessed via the Ski Park Highway. http://www.mtshastanordic.org
The Pilgrim Creek & Deer Mountain Snowmobile Parks are open! Trails are being groomed currently. Head to our "Education" tab on our website and find the snowmobile section for trail information, grooming status and other sledder resources!
The Castle Lake road is plowed to the Vista Point. The Everitt Memorial Highway is plowed to Bunny Flat.
The Five Red Flags of Avalanche Danger any time of year include: 1) Recent/current avalanche activity 2) Whumpfing sounds or shooting cracks 3) Recent/current heavy snowfall 4) Strong winds transporting snow 5) Rapid warming or rain on snow.
Weather and Current Conditions
Weather Summary
Good Morning! In Mt Shasta City at 0500, we have a current temperature of 38 F, 2 degrees warmer than yesterday at this time, with obscured skies and light wind.
On Mt Shasta (South Side) in the last 24 hours...
Old Ski Bowl - 7,600 feet, the current temperature is 29 degrees F. Snow on the ground totals 72 inches with no new snow and 2 inches settlement. Temperatures have ranged from 24 F to 30 F.
Grey Butte - 8,000 feet, the current temperature is 28 degrees F. Temperatures have ranged from 22 F to 28 F. Winds have been averaging 5-10 mph and westerly in nature with a max gust to 21 mph.
Mt Eddy Range (West side of Interstate-5)...
Castle Lake - 5,600 feet, the current temperature is 31 degrees F. Temperatures have ranged from 27 F to 33 F. Snow on the ground measures 50 inches with no new snow and 2 inches settlement.
Mt Eddy - 6,500 feet, the current temperature is 30 degrees F. Temperatures have ranged from 27 F to 31 F. Snow on the ground measures 56 inches with no new snow and 2 inches of settlement. Winds have averaged 2 mph and southerly in direction, with a max gust to 10 mph, south.
Always check the weather before you attempt to climb Mt Shasta. Further, monitor the weather as you climb. Becoming caught on the mountain in any type of weather can compromise life and limb. Be prepared.
| 0600 temperature: | 32 |
| Max. temperature in the last 24 hours: | 33 |
| Average wind direction during the last 24 hours: | Westerly |
| Average wind speed during the last 24 hours: | 5-10 mi/hr |
| Maximum wind gust in the last 24 hours: | 21 mi/hr |
| New snowfall in the last 24 hours: | 0 inches |
| Total snow depth: | 63 inches |
Two Day Mountain Weather Forecast
Produced in partnership with the Medford NWS
| For 7000 ft to 9000 ft | |||
|---|---|---|---|
|
Tuesday (4 a.m. to 10 p.m.) |
Tuesday Night (10 p.m. to 4 a.m.) |
Wednesday (4 a.m. to 10 p.m.) |
|
| Weather | Snow before 4pm, then rain and snow, chance of precip 90% | Rain and snow, becoming all snow after 10pm, windy, chance of precip 100% | Snow showers, breezy, chance of precip 100% |
| Temperature (°F) | 33 | 29 | 31 |
| Wind (mi/hr) | South/Southeast 15-20 mph, increasing to 20-30 mph | South 20-30 mph with gusts higher | South/Southwest 15-20 mph |
| Precipitation SWE / Snowfall (in) | / 3-7 | / 9-13 | / 4-8 |
| For 9000 ft to 11000 ft | |||
| Tuesday | Tuesday Night | Wednesday | |
| Weather | Snow, increasing winds becoming very windy. High wind warning in effect 10am this morning to 7am Wednesday | Snow, very windy | Snow showers, very windy |
| Temperature (°F) | 24 | 22 | 14 |
| Wind (mi/hr) | Southwest 25-35 mph, increasing | South/Southwest 5-9 | West/Southwest 50-60 mph with gusts higher |
| Precipitation SWE / Snowfall (in) | / 5-9 | / 15-21 | / 10-14 |
