2019 - 2020 Season Snowfall So Far...

As we move into 2020, we thought it might be a good time to recap the end of 2019 and where we stand so far. We've had some really good skiing and riding so far, that got off to a late start in the end of November but since then has been a steady parade of storms through December.

The first snowfall of the year that had any impact for us was October 25th with 2" of snow and .2" of SWE.  Another storm October 29th into the 30th left us with an additional 4 to 6" and .3 to .4" of water.  This snow lingered on Northerly aspects above 11,000' while we went through a high and dry period for the first three weeks of November. The first snowfall in November was on 20th but in the mean time warm temperatures and sunny skies filled the first three weeks of the month.

Long Canyon on Nov 18th before the Nov 20th storm.  Faceted snow lingers on northerly and shady aspects above 11,000'

The first snow in the month of November fell on 20th going into the 23rd.  This storm brought 20.5" of snow with 2.15" of water. This storm started out warm with temperatures of 35 degrees at 10AM at 9000’ and precipitously dropped during the storm.  Winds were out of the WSW during the duration of the storm.  This was a right side up storm coming in wet and warm and leaving cold and dry.  Winds were in the 20 MPH range at ridge tops and dropped into the single digits as the storm made its exit.  This storm left us with quite a base, falling on bare ground on most slopes or 1-3mm facets on northerly aspects above 11,000'. We did not observe any natural avalanche activity.

The November 25th Storm:  This storm had less to do with precipitation and more to do with the strong winds.  This storm came in warm and only dropped 2-3” of snow with .15-.25” SWE by the morning but continued to see orographic showers throughout the day with low density snow as temperatures dropped and winds diminished.  Winds were out of the SW (20 – 30 MPH) with gusts in the 60’s during the first part of the storm overnight, which left stiffening wind slabs and 4” of low density snow on top. In total we had 6 to 8” of snow with this storm and about .35 to .45” of SWE.

Start of the Thanksgiving Day Storms:  The 27th started out sunny with clouds rolling in during the afternoon and snow starting in the evening.  This started as a warm storm that brought 4-6” of new snow with about .6” of SWE.  Winds picked up in front of and during the initial bit of the storm with SW winds in the (20-30 mph) range gusting in the 50’s. 

Thanksgiving day brought a lull in storms with mostly cloudy weather before the final of the storms arrived 11/29 at 1PM with strong WSW winds and good amount of precip.  Snow and SWE measurements surely were skewed by the wind transported snow.  8-10” of snow fell with what was measured as 1.7” of SWE (very much skewed) .  This was the storm that tip the scales with our lingering weak faceted snow from October.

The first avalanche event of the season was during the evening of 11/29 or early morning 11/30 when we went through Peak Instability.  There were many naturals on North facing aspects ATL in the backcountry.  These slopes harbored the weak basal facets from lingering October snow.  Stability tests were indicating moderate force to initiate these basal facets with full propagation.  Strong winds in the 80’s with over an 1” of water was enough to tip the scales.

Photo Taken: November 30th in the morning. Natural avalanche on Sin Nombre 

DECEMBER:

The first storm of December arrived on the night of 12/4 and continued into mid day on the 5th. The storm arrived at 11:00pm with temperatures below freezing, 30 degrees approximately. Temperatures slowly dropped into the mid 20’s by the end of the storm. Winds were from the southwest between 15-20 MPH, and gusted into the 30’s. This storm deposited 4-6” of mostly graupel with .2” of SWE. This was the first of many graupel storms that we had during the month of December.

Storm 12/8-12/9

The storm deposited 6-10” of new snow, with .7-1.1 inches of SWE. Post storm western winds produced wind slabs near and above tree line. These wind slabs ranged from 10cm to 60cm in depth. They formed on top of a variety of surfaces, from a weak graupel layer to sun crusts. While we did not observe any natural avalanches in the backcountry, snow safety teams were getting these storm slabs to avalanche with several stepping down into older layers.

Storm 12/15-12/16

Storm totals of 10-14” of snow with .8 to 1.2 inches of SWE. The storm came in warm, and left cold with moderate western winds. We observed several small D1 natural storm slab avalanches, with a couple larger slides which may have stepped down into our mid pack faceted layers. We saw repeat runners for avalanche paths during this natural avalanche cycle.

Avalanche Debris off the backside of Kachina Peak that ran naturally on December 16th

Christmas Storm 12/25-12/26

The Christmas eve storm brought 5-8” and .5 to .7 inches of SWE, along with steady SW winds in the 20’s and gusts into the 40’s.  These winds created stiff cohesive slabs on North through East aspects, on the leeward side of ridges as well as cross-loaded slopes. A natural storm slab avalanche was observed above tree line, but we did not have any reports of avalanches stepping down into older layers. Avalanche control teams reported wind slab avalanches below ridgelines with ski cuts and small explosives. These slabs were not bonding well to the old existing surface. 

Storm 12/27-28

The two separate storms totaled 12-16” of low density snow, along with .9 to 1.2 inches of SWE. The first storm 12/27 brought 5 to 8” of new snow with moderate to strong WSW winds. Gusts climbed into the 60’s. This wind formed cohesive slabs on the surface near and above tree line. The Saturday storm brought an additional 8-10” of low density snow, along with calm winds. Instabilities came in the form of loose dry avalanches and soft surface storm slabs, but we did not have any natural avalanches stepping down into older weak layers. We did get reports of avalanche mitigation teams getting avalanches to step down into old layers like the buried graupel layer from 12/5 that wasn't showing signs of healing. 

JANUARY

As of January 6th our last significant snowfall was from the 12/28 storm.  We had a small storm on January 3rd of 2 to 3" of low density snow.  This prolonged high pressure has brought lots of sun and for the most part cold temperatures, especially at our higher elevations.  

Except for January 4th and 5th we've had below freezing temperatures with cold clear nights.  Overall our snowpack is not impressively deep, for the amount of snow we've received since the end of November.  Many slopes are well under 2 meters and have mid-pack weak layers from faceting crusts that formed during high pressure periods of December 1st - 4th, 9th - 14th and 17th - 24th. 

The Depth Hoar that we are so accustomed to, was mostly flushed during the 11/30 and 12/16 avalanche cycles. Even though we are not dealing with this persistent weak layer, we have several mid-pack and basal facet layers that may rear their ugly head once we get additional snow and these layers become reactive again.