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Avalanche Advisory for 2013-03-29 06:46:54
- EXPIRED ON March 30, 2013 @ 6:46 amPublished on March 29, 2013 @ 6:46 am
- Issued by Nick Meyers - Shasta-Trinity National Forest
Bottom Line
The avalanche danger today is low for all aspects and elevations. The forecast area has received 1" - 4" of wet snow (.28" water) at elevations above 6,500 feet in the past 48 hours with little wind. Temperatures today will be warm with a high near 50 F near treeline. A chance of scattered rain showers is possilbe in the afternoon. Conditions are WET and are going to continue to be wet through the weekend. A storm will let loose over the area on Saturday and Sunday bringing significant precipitation. We could see up to .5" of rain and snow levels at 7,500 to 10,000 feet. Loose-Wet Avalanches are going to be the main concern for the next few days and the avalanche danger will likely rise as this storm develops on Saturday.
Avalanche Problem 1: Wet Slab
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Likelihood ?CertainVery LikelyLikelyPossible
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Wet-Loose avalanches will be possible today and this weekend. A few inches of new snow in the past 48 hours with warm daytime highs could create areas of wet-loose activity. Southerly facing slopes steeper than 35 degrees should be most suspect. As our snowpack receives the forecasted precipitation this weekend, wet-loose avalanche activity could rise. Wet Loose slides involve the release of wet, unconsolidated snow or slush. These slides typically occur within layers of wet snow near the surface of the snowpack, though can gouge into lower snowpack layers. They usually start at a point and entrain more snow as they move downhill, forming a fan-shaped avalanche. Wet loose slides generally move slowly, but can contain enough mass to easily cause damage to trees, etc., not to meniton human life and limbs.
Recent Observations
Good skiing conditions were found yesterday with a couple inches of new snow fallen in the past 48 hours. New snow was very wet below treeline. Firm snow and a stabe, isothermic snowpack exists overall. Castle Lake area snow coverage is getting thin and most folks are not venturing onto the lake due to soft edges.
The main concern will be for the next two days. Significant precipitation and moderate southerly winds are expected for Saturday and Sunday. Upwards of .75" of water is predicted for areas west of the Cascades...we could see upwards of .5" in our area. This storm will be warm and host high snow levels, at times as high as 10,000 feet. This means wet, full winter conditions on Mt. Shasta. A summit attempt is not advised.
As spring approaches and temperatures begin to warm, spring skiers and climbers should keep WET-LOOSE AVALANCHES in mind. Sunny days and spring time can cause folks to forget their "avalanche awareness". Loose-wet slides occur every year on Mt. Shasta and can be very large and harmful to human life!
Significant rain can also cause WET-LOOSE AVALANCHES. Use caution this weekend.
This is a great video from the Gallatin Avalanche Center, Bozeman, MT demonstrating small loose-wet slides: http://www.youtube.com/watch?v=zWpRQzgtL3o&feature=share&list=PLXu5151nmAvT7gHqdNajDBGfGY4u5XMSL
Weather and Current Conditions
Weather Summary
A closed low moves into the area this weekend. Decent and dry weather should host today with temperatures warm...reaching 70 degrees for the first time this year at the Rogue Valley Int'l Airport! Scattered showers are posssible this afternoon. Of most importance will be the storm for Saturday and Sunday which will bring significant precipitation to the area and high snow levels. Up to .5" of water is forecasted with snow levels 7,500 to 10.000 ft. Winds look to be moderate with this storm. With spring break on tap, climbers thinking of a summit attempt of Mt. Shasta should take note of this weather. It's very likely that conditions will be wet and stormy with low visibility.
WEATHER STATIONS - (last 24 hours):
In Mt. Shasta City at 0500, we have clear skies and with and a current temperature of 39 F.
On Mt. Shasta: In the Old Ski Bowl (7,600') on the south side of Mt. Shasta, we have a current temperature of 29F. Snow on the ground totals 106" inches with 2" - 4" new snow in the last 48 hours. Temperatures have ranged from 29 F to 35 F. At Grey Butte (8,000') on the south side of Mt. Shasta winds averaged 10 mph from various directions with a few gusts to 21mph from various directions as well. The current temperature is 29F and temps have ranged 29F to 33F.
Castle/Mt. Eddy: Castle Lake - Castle Lake is hosting a current temp of 36F. Temperatures have ranged from 34F to 39F. Snow depth measures 38" inches with 1" new snow and 4" settlement since last weekend.. On Mt Eddy, we have 59" inches of snow on the ground with 2" - 4" new snow in the past 48 hours and little settlement since last weekend. The current temperature reads 32F with temps ranging from 32F to 36F. Winds have been averaging 1 mph from the SW and gusting to 13 mph - SW.
THIS SEASON: September and October were warm and dry with September recording exactly zero precipitation. November remained warmer than normal with precipitation almost double normal values, 9.16" vs. 5.08". A local weather COOP observed the 2nd wettest November on record. December started out wet and warm, but temperatures cooled and brought snow to very low elevations. Since our avalanche cycle near Christmas, we've had a few small storms that brought some amounts of snow to the area, but did not produced any notable avalanches. January was below normal for precipitation with a long period of high pressure and sun that kept skiing conditions somewhat meager. We've had a few storms for 2013 that have brought us glimpses of wintery weather, but nothing to write home about! California and the Sierra Nevada have recorded the driest January and February on record. We currently have 5'-8.5' feet of snow above 6,500 ft. Since September 1st, Mt Shasta sits at 69% of normal, 24.93" recorded; normal 35.74". For 2013, we sit at 21% of normal with 4.23" recorded and 19.86" normal.
| 0600 temperature: | 31 |
| Max. temperature in the last 24 hours: | 36 |
| Average wind direction during the last 24 hours: | Various |
| Average wind speed during the last 24 hours: | 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: | 58-106 inches |
Two Day Mountain Weather Forecast
Produced in partnership with the Medford NWS
| For 7000 ft to 9000 ft | |||
|---|---|---|---|
|
Friday (4 a.m. to 10 p.m.) |
Friday Night (10 p.m. to 4 a.m.) |
Saturday (4 a.m. to 10 p.m.) |
|
| Weather | Cloudy this morning, becoming partly cloudy with some sun as well! | Partly cloudy in the evening, then becoming mostly cloudy. Rain showers after midnight. | Cloudy, chance of rain in the morning, and rain likely in the afternoon. |
| Temperature (°F) | 50 | 32 | 50 |
| Wind (mi/hr) | South 5-10 mph | Southeast 5-10 mph | East, shifting to southwest 5-10 mph |
| Precipitation SWE / Snowfall (in) | / 0 | / 0 | / 0 |
| For 9000 ft to 11000 ft | |||
| Friday | Friday Night | Saturday | |
| Weather | Cloudy this morning, becoming partly cloudy with some sun as well! Breezy | Cloudy and windy | Mostly Cloudy and windy |
| Temperature (°F) | 31 | 28 | 33 |
| Wind (mi/hr) | Southwest 20-30 mph with gusts higher | South 0 | South, becoming ENE in the afternoon 20-30 mph with gusts higher |
| Precipitation SWE / Snowfall (in) | / 0 | / 0 | / 0 |
