Tue, March 14, 2023 Turnagain Pass Avalanche Forecast

Tue, March 14th, 2023

Alpine

Above 2,500'

1 - Low

Treeline

1,000'-2,500'

1 - Low

Below Treeline

Below 1,000'

1 - Low

0 - No Rating

1 - Low

2 - Moderate

3 - Considerable

4 - High

5 - Extreme


Travel Advice	Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.	Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.	Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential.	Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.	Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches	Natural and human-triggered avalanches unlikely.	Natural avalanches unlikely; human-triggered avalanches possible.	Natural avalanches possible; human-triggered avalanches likely.	Natural avalanches likely; human-triggered avalanches very likely.	Natural and human-triggered avalanches certain.
Avalanche Size and Distribution	Small avalanches in isolated areas or extreme terrain.	Small avalanches in specific areas; or large avalanches in isolated areas.	Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.	Large avalanches in many areas; or very large avalanches in specific areas.	Very large avalanches in many areas.

Recent Avalanches

Yesterday skiers reported a small natural avalanche on the Eddie’s Headwall. It looks like it may have been triggered by a falling cornice, and is probably a few days old. More details in this observation.

Photo of the Eddie’s Headwall, taken yesterday. The avalanche looks to be a few days old. Photo: Eric Steinfort, 03.13.2023

Avalanche Problem 1

Normal Caution

Normal Caution

Normal Caution means triggering an avalanche is unlikely but not impossible.

More info at Avalanche.org

The biggest factor driving the avalanche danger today is the timing of the approaching storm. It is looking like we won’t see very much precipitation until shortly before sunset today, which means the avalanche conditions should stay generally safe for most of the day. It will be important to pay attention to changing conditions as the weather picks up, and look out for increasing avalanche danger if the storm arrives sooner than expected.

Until it starts snowing, the main thing to watch out for will be small avalanches in isolated upper-elevation terrain. It is important to remember that although the danger is low, it is not impossible to trigger an avalanche. With a few hours of gusty winds yesterday afternoon, there may be some lurking pockets of reactive wind slabs. Stay smart with your travel habits- only exposing one person at a time to steep terrain and watching partners from safe spots out of avalanche runout zones. With deteriorating weather conditions expected today, it is probably a good idea to plan on getting out of the mountains a little earlier so you don’t get stuck in an uncomfortable situation as the storm ramps up and avalanche danger starts to rise.

It’s not much, but it is something! Snowfall is expected to start this afternoon and continue through Wednesday. There is high uncertainty with timing, and some areas may see higher snow totals. Be on the lookout for increasing danger as the storm ramps up. Graphic courtesy of NWS Anchorage. 03.14.2023

Additional Concern

Persistent Slabs

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

More info at Avalanche.org

We are still concerned with the possibility of triggering a larger avalanche on a layer of weak facets buried about a foot deep down in the southern edge of our forecast area. This layer is most problematic between Pete’s North and Johnson Pass, and was the culprit in a large skier-triggered avalanche last Monday (3/6). These stubborn persistent weak layers can be difficult to predict, so the best way to manage them is by avoiding steep slopes in this area.

Weather

Tue, March 14th, 2023

Yesterday: Skies were mostly sunny with a few clouds moving in later in the day. Winds were 5-10 mph out of the west for most of the day, with a few hours in the afternoon of speeds around 10-15 and gusts as high as 30 mph on Max’s. Portage recorded stronger easterly to northeasterly winds at around 5-15 mph with gusts around 25 mph. Temperatures reached the low to mid 20’s at lower elevations, staying in the single digits to low teens near ridgetops during the day, and dropped down to single digits above and below zero overnight. No precipitation was recorded yesterday.

Today: A pattern change is underway as a low pressure system in the Gulf brings increasing cloud cover and winds switching back to the east at 5-10 mph with gusts of 10-20 mph. The weather is looking to get more active late in the afternoon, with increasing winds and snowfall expected to start around 4 pm. We will likely only see a trace to 2” snow during daylight hours today, with another 2-4” possible tonight. Precipitation during this storm is expected to be spotty and difficult to predict, so some areas may see more than double those precipitation totals. Temperatures are expected to get into the mid to upper teens F during the day before dropping slightly to the low to mid teens early tonight. It is looking like snow line should stay down to sea level for this first round of precipitation.

Tomorrow: Snowfall should continue tonight into tomorrow, with another 1-2” likely during the day tomorrow. Easterly winds are expected to pick up tonight, blowing 15-25 mph with gusts of 20-30 before backing off slightly during the day tomorrow. Skies should be mostly cloudy during the day and high temperatures are expected to be in the low to mid 20’s F with lows in the low to mid teens F.

PRECIPITATION 24-hour data (6am – 6am)

	Temp Avg (F)	Snow Depth (in)
Center Ridge (1880′)	16	64
Summit Lake (1400′)	13	37
Alyeska Mid (1700′)	16	64
Bear Valley – Portage (132′)	15	–

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	3	WNW	4	15
Seattle Ridge (2400′)	9	NW	4	14

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
04/16/24	Turnagain	Observation: Cornbiscuit	Krueger / Matthys Forecaster
04/15/24	Turnagain	Observation: Taylor Pass	John Sykes Forecaster
04/15/24	Turnagain	Observation: Seward Highway – Tern Lake to Portage	Joel Curtis
04/14/24	Turnagain	Observation: Sunburst	T. Olsen-Lund, R. Sullivan I. Adams
04/14/24	Turnagain	Observation: Turnagain Pass Snomo	K. Gallaher
04/13/24	Turnagain	Observation: Spokane Creek	Everet Megli
04/11/24	Turnagain	Observation: Tincan	John Sykes Forecaster
04/10/24	Turnagain	Avalanche: Seattle Ridge	Schauer/ Keeler Forecaster
04/10/24	Turnagain	Observation: Cornbiscuit South Face	Todd Kelsey
04/10/24	Turnagain	Avalanche: Tincan	N. Dumont J. Carlberg

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