The Mt. Shasta Avalanche Center - US Forest Service       

Avalanche Advisory issued:

Saturday, February 4th, 2012                   By: Keith Potts                                             

***Free Transceiver Clinic today, February 4. Click here for more information.***

Avalanche Danger Rating* for today:

24 hour trend:

	Avalanche danger is expected to increase.
	Avalanche danger is expected to continue at this rating
	Avalanche danger is expected to decrease

Where:   Expect LOW avalanche danger on all aspects above and below treeline.

Primary Concern:  Small, isolated areas of wind loading (wind slabs) above treeline on southerly slopes steeper than 35 degrees. Be mindful in bowls and ridge tops, above treeline

Secondary Concern: 

Size and Character:  Small slabs, chunky and blocky.

Sensitivity to Triggering:  Above and below treeline, slabs may be stubborn to unreactive to trigger.

Confidence in today's forecast:

The Details:

This Season:   Strikes and gutters...we started off the 2011 winter season with some early season snow, perking everyone's head in hope of a heavy winter. December and part of January were almost completely dry, dropping the jaws of all snow junkies...and then, a mid January blast lifted spirits and brought smiles as feet of snow fell on the area. Face shots were found and life was good...until our familiar friend, Mr. Rain on snow decided to stop into town! Mr. Rain squished our snowpack down to a hard, runneled mess and now, sunny skies and an expected dry beginning of February will likely return anxiety amongst a few folks. We currently sit in weak to moderate La Nina conditions and this is expected to continue through Spring of 2012. Models, however, do indicate the Madden/Julian Oscillation has strengthened and will be active for the next few weeks, possibly bringing a stronger jet and wetter conditions to the western US.(Click here to read about the Madden/Julian Oscillation) Mt. Shasta, for the month of February, is now just 26% of normal. Since September 1st, we have received 45% of our normal precipitation or 10.58 inches. January finished out at 76% of normal for 2012. 

Weather Observations at 5am:   In Mt. Shasta City this morning we have clear skies and a current temperature of 25 F.  No new snow fell in our forecast area in the last 24 hours.
On Mt. Shasta (South side):  In the Old Ski Bowl (7,600'), we currently have 38 inches of snow on the ground with an inch of settlement and a 5am temperature of 30 F. Yesterdays high reached 46 F at 10am and dipped to 28 F at 3am this morning.
On Grey Butte (8,000') variable winds have averaged 10 mph over the last 24 hours with gusts to 28 mph from the E. The current temperature is 30 F with a daytime high yesterday of 44 and a low of 29.
Castle Lake/Mt. Eddy (West side of I-5):   At Castle Lake (5600') we have 33 inches of snow on the ground with 1 inch of settlement and the current temperature this morning is 27 F. In the last 24 hours temperatures peaked at 39 F with a low of 27 F.  On Mt Eddy, we have 37 inches of snow on the ground with about a half inch of settlement in the last 24 hours. Temperatures have ranged between 23 F to 44 F with a current temp of 23 F. Winds have averaged 2 mph from the SW with gusts to 10 mph from the W.

Weather Forecast:  If you didn't catch the news yesterday, shadows were seen on official and unofficial groundhogs locally and nationally, so we can all relax- six more weeks of WINTER on the way...let's make it twelve! Punxsutawney Phil sees his shadow on Groundhog Day, 2012! (Click here).  Upper air temperatures this morning were 1 to 2 degrees F cooler than yesterday at this time with very calm winds even at 30,000 feet.  These conditions will be well represented on the ground with slightly cooler temperatures and mild winds throughout the Mt. Shasta forecast area today as high pressure sits overhead. Below treeline today expect sunny skies with temperatures in the low to mid 40's with light variable winds.  Above treeline and on the upper mountain expect temperatures in the low to mid 30's with calm east winds.  The next possibility for measurable precipitation will be Tuesday and a pacific low moves into our area. Unfortunately models indicate the system will lose its energy as it confronts our imbedded high pressure and give us little in the way of moisture.

Snowpack:  With temperatures up to 13 degrees F colder this morning on Mt. Shasta than yesterday at this time and below freezing temperatures for the first time in 2 days in some locations, expect surface conditions to be hard today and be slower to soften above treeline.  Bottom line: variable conditions will be found in the Castle Lake and Mt. Shasta area backcountry including exposed rocks and brush, grabby crusts, mid-day corn, isolated wind pillows, scoured pockets and areas of dry powder on low angle shaded aspects. The good news is a mostly bomber snowpack exists with no signs of instability observed or reported.
In the past 3 weeks we received 100 cm new snow followed by a rain on snow event that left elevations below treeline with a 25-40 cm crust and above treeline with 4 to 6 inches of new snow. With time these layers have bonded well and are continuing to strengthen with an active melt-freeze cycle. Moderate NE winds have transported some of this snow onto leeward, SW slopes above treeline. Pockets of wind slabs may be present above treeline, though will be stubborn to unreactive to trigger.

VIDEOS:.

Warming and rain on snow...Mt. Eddy area, 1-24-12

Gray Butte rutschblock test and a look at the new snow ! 1-22-12 !!

Castle Lake in the storm...windloading 1-19-12

Link to video of facet layer at Cliff Lake
 

PHOTOS:

A look down at the Powder Bowl slide path, South Side, Mt. Shasta...notice all the missing trees. Large avalanches have crossed the Everitt Memorial Highway in the past.  {Photo: Meyers 1-28-12}


The effects of RAIN ON SNOW, near Bunny Flat...Yuck....       {Photo: Meyers - 1-28-12}

The next three pictures are natural avalanches that occurred on 1-21-12 up near Castle Lake. All three were up above the lake near the ridge top of middle peak where we typically see a lot of wind loading. Wind loading on top of the old, rotten, faceted snow was the cause of these avalanches. The second avalanche in the picture set has a crown of about 4 feet! We will continue to see more wind loading and the faceted layer that these avalanches slid on is not going away anytime soon. More pockets of instability like we are seeing below most likely exist! Remember, mother nature gives up FREE warning signs of instability, and natural occurring avalanches are one of them! Be safe...                                                 {Photos: Kai Allen}

 
Example of faceted snow a.k.a. "sugar snow", notice angular, obtuse sides           Photo: Google Images

Pilgrim Creek Snowmobile Park:  OPEN - grooming will begin soon.  More snow is needed.

Please report weather and snow observations- you could help save a life:  (530)926-9614  Thanks!