Friday 31 May 2019

No news – gray skies, lots of snow at high altitude, also avalanche danger

Last week’s weather: variable. Mostly gray skies and rainy, with brief intervals of improvement and dispersed clouds (23-25 May).

Weather station Hahnenkamm (Reutte): for a station at 1670m, still enormous amounts of snow

The predominantly gloomy, cold, wet weather will persist for a bit.

Rainfall up to about 2500 m in most parts of Tirol. Tirol’s highlands (photo: 28.05.2019)

The ZAMG weather service published a report of special precipitation events on Monday, 27 May: “A low over Scandinavia and a low over Italy will bring moist air masses to the Alps from the north and from the south. Until Wednesday, gray, wet, cold weather will prevail in Tirol with sometimes heavy rainfall in the northern barrier-cloud regions from Ausserfern to the Wilder Kaiser. In the mountains, significant amounts of fresh snow are anticipated above the timberline. On Thursday, Ascension Day, slight high-pressure zone influence and slightly improved weather conditions.”

24-hour precipitation 2019-05-28 at 2:00 pm

From the Stubai Alps to the Venediger Massif, ample amonts of snowfall are anticipated.

Starting on Ascension Day (30 May) the weather will steadily improve. With regard to possible avalanches, the same scenario is expected as following the intensive period of precipitation last week: as solar radiation increases, including daytime warming, numerous loose-snow avalanches, some of which will be superficial slab avalanches, will trigger. Following a swift settling impulse, the frequency of avalanches will then decrease noticeably.

Numerous loose-snow avalanches (in foreground, also a superficial slab avalanche) triggered between 23 and 25 May. Wilder Leck in the Stubai Alps (photo: 26.05.2019)
Characteristic of this winter and the generally stable old-snowpack layering is the complete lack of large-sized slab avalanches which fractured in deep-down layers. Still theoretically possible in very isolated cases in high alpine regions on very steep, shady slopes are fractures immediately beneath the glacier ice see blog.

Still not to be ruled out: isolated gliding snow over smooth ground. Arlberg region  (photo: 26.05.2019) 
Incidentally, the winter also brought about some forest damage....

Snapshot from the region on the border to the Salzburg province: pressure created by the weight of snow bent and mangled the trail signs and (in background) the trees.  (photo: 23.05.2019)

Wednesday 22 May 2019

Results of Euregio Avalanche Bulletin Survey

At the end of March we carried out an online survey to determine reader satisfaction with the new Euregio Avalanche Bulletin. We would like to thank everyone who participated in this survey, who took the time to answer the questions. We have studied the results carefully. Based on your responses, we are taking appropriate measures to improve the Euregio Avalanche Bulletin.

We received a total of 3555 filled out questionnaires within two weeks. In general, those who took part in the survey were quite satisfied with the Euregio Avalanche Bulletin and viewed the change as positive. An additional query about avalanche-specific knowledge revealed that survey participants who are active in outlying terrain are very well informed about the given avalanche situation. The Euregio Avalanche Bulletin is very important to most of them when planning a variety of winter activities, e.g. snowshoe hiking, freeriding, backcountry skiing tours and ice climbing. That includes persons aged 14 to 81 from all three regions.

Nevertheless, those who took part in the survey are not a representative cross-section of all those who actively engage in winter sports in outlying terrain away from secured and marked ski runs. Most survey respondents were from Tirol, speak German, are backcountry skiers, male, on average 41 years old, very active, and have a relatively high level of education.


PRIZE GAME
The winners of the prize game were drawn and have been notified via e-mail. We extend warm congratulations to all of them!


RESULTS IN DETAIL
The questionnaire was sub-divided into several sections. They included questions about the quality of the Euregio Avalanche Bulletins and about the education levels of the participants.

Old-style Avalanche Bulletins/Forecasts vs. Euregio Avalanche Bulletins
In winter 2018/2019 the old-style Avalanche Bulletins and Forecasts of the Avalanche Warning Services of Tirol, South Tirol and Trentino were bundled together and completely re-designed. So of course, we want to know whether these changes are being viewed as improvements.
More than half of the respondents were of the opinion that the Euregio Avalanche Bulletins are, in general, “somewhat better” or “a lot better” whereas 22.9% viewed the change as having brought about neither improvement nor deterioration and 8.4% were of the opinion that the new Euregio Avalanche Bulletins are worse than the old-style Avalanche Bulletins (Fig. 1). It was interesting that not just design and comprehensibility, but also contents were judged to be somewhat “better” or “a lot better” by 63.8% of the respondents, compared to the old-style Avalanche Bulletins and Forecasts.

Fig. 1 Percentage of survey participants (n=3555) who found the contents, comprehensibility, design and informational value of the new Euregio Avalanche Bulletin “much worse,” “worse,” “about the same,” “somewhat better” and “a lot better” than the old-style Avalanche Bulletins.

Satisfaction with the Euregio Avalanche Bulletin
The majority of respondents assessed the Euregio Avalanche Bulletin contents in particular as “very good.” However, the visualization and the language quality of both sections, Danger Assessment and Snowpack, were judged merely as “rather good.” Only very few respondents found the bulletin to be “very bad” or “rather bad” (Fig. 2).

Fig. 2:  Percentage of survey participants (n=3555) who rated the contents, comprehensibility, design, language quality of Danger Assessment and language quality of Snowpack Description as “very bad,” “rather bad,” “neither bad nor good,” “rather good,” and “very good.”

Quality of the forecasts
Respondents were asked to judge the quality of the avalanche forecasts. The were of the opinion that the forecasts were correct about 85.9% of the time during the winter season.

Criticism
Lots of people initially had trouble navigating the newly designed website. These problems were resolved swiftly after a short introductory phase.
Often criticized on the new website:
  • Technical problems, website downloaded too slowly, compatibility problems with mobile devices.
  • Presentation of morning / afternoon situations on the avalanche danger map was often not clear in the beginning phase.
  • Visualization of automated measurements was not optimal.
  • General handling of snow maps and weather maps was criticized.
  • Some users missed direct access to avalanche events, since they could only be called up indirectly via www.lawis.at.
Some of the problems have been solved in the interim. We are working on the other points, as well as other improvements which go beyond the things criticized, e.g. an additional version of the website in case of poor Internet connection; measurement station diagrams included in the snow maps and weather maps, etc.


PERSONAL DATA
The respondents were users of the Euregio Avalanche Bulletins. Accordingly, their answers did not supply representative responses of all users of Avalanche Warning Service products.

Age
The age spectrum of participants was huge (Fig. 3A). The oldest participant was 81 years old, the youngest was 14. The median age was 41.

Gender
Women were severely underrepresented in the survey. The overall percentage of female respondents was 16.6% (South Tirol: 17.3%; Tirol 16.6%; Trentino 9.6%). A Swiss study showed that 45% of total days spent backcountry touring are undertaken by women.

Fig. 3: (A) Age-distribution of survey participants, depicted in five-year steps (n=3555). Red line: median age. (B) Gender distribution of survey participants.  

Language and preferred touring region
Most of the questionnaires were filled out in German (Fig. 4A). Most of the survey participants reported that they were most frequently on tours in Tirol, i.e. North Tirol and East Tirol (Fig. 4B).

Fig. 4: Percentage of survey participants (n=3555) according to (A) language the survey was answered in; (B) preferred touring region of survey participants.

Information gain for individual tour planning
Most of the survey participants reported they always (80.8%) or usually (18.11%) informed themselves about avalanche danger before they ventured into backcountry terrain.

Knowledge of Euregio Avalanche Bulletin
Most survey participants are acquainted with the individual sections of the Euregio Avalanche Bulletin “very well” or “well.” General information is better known than details. Accordingly, knowledge of the avalanche danger level was known “very well” or “rather well” to nearly all survey participants (98.5%). Description of the snowpack layering, on the other hand, was known “less well” to many of the survey participants (Fig. 5).

Fig. 5  Percentage of survey participants (n=3555) who know various sections of information contained in the Euregio Avalanche Bulletin “not at all,”, “only slightly,” “rather superficially,” “rather well,” and “very well.”

The results tend to reflect the information pyramid (Fig. 6) which is used for the contents of the Euregio Avalanche Bulletin and, incidentally, which is also recommended by the European Avalanche Warning Services (EAWS). According to this structure, users first absorb the easily grasped, clearly presented information, and study the details only at the end.

Fig. 6: Information pyramid used by the EAWS

Snow and avalanche education
As can be seen in Fig. 7A, about 40% of survey participants have had some formal avalanche education, e.g. mountain guides, ski instructors, etc.

Self-assessment in evaluating avalanche danger
As reflected in Fig. 7B, the majority of respondents who were asked to evaluate their own abilities described them as “medium” (53.6%) or “great” (32.2%). This evaluation is of course subjective, yet it correlates with the high percentage of survey participants who have had some avalanche-specific  education.
It is likely that interested and better educated winter sports activists also use the website more often and for that reason are more likely to supply answers in a survey. In addition, such people are presumably more likely to fill out a survey questionnaire since this subject is highly interesting to them; perhaps they also see a possibility of submitting their own input.

Fig. 7:  Percentage of survey participants who (A) have had some avalanche-specific education and who (B) evaluate their experience in assessing avalanche danger as “very little” (0.7%), “little” (8.8%), “average” ( 53.6%), “great” (32.1%) and “very great” ( 4.7%). 

Avalanche courses completed
As illustrated in Fig. 8, most of the survey participants (88%) have taken at least one avalanche course, e.g. an avalanche course sponsored by the Alpine Club, etc. However, most have taken several courses (most often 2-3). This result corroborates the fact that for the most part, well educated persons who are interested in this subject are also the ones who took part in the survey.

Fig. 8: Number of survey participants who have taken zero, one, two-to-three, four-to-five, 6-10, 11-20, more than 20 avalanche courses and number of survey participants who were involved in such courses as an instructor.

Type and length of winter sports activities in outlying terrain
Survey participants consider themselves to be enormously active. Accordingly, the average number of days they were engaged in sports in outlying terrain, i.e. on backcountry skiing or freeriding tours away from secured and marked ski runs, was about 34 days.

The majority (68.4%) of days spent in outlying terrain was for backcountry skiing tours. One fifth of the days spent in outlying terrain (20.8%) was for freeriding with skis and 3.7% for freeriding with snowboard (Fig.9).


Fig. 9: Percentage distribution of winter sports in outlying terrain.

Individual responsibility

92.9% of survey participants reported they undertake backcountry tours on their own responsibility. The remaining 7.1% join other experienced persons or remain on secured and marked ski runs.

(The survey results were evaluated by our apprentice Clara Bertel.)

Friday 17 May 2019

Wintery conditions persist in the mountains – weather remains variable

Still unstable and cool

The variable weather conditions, rather cool and moist for this juncture of the season, persist.

Weather review: highly variable!

A comparative review: the winter’s greatest snow depths are frequently being measured in high alpine regions currently.

Impressive amounts of fresh snow in the mountains

Conditions as in deep winter at Regensburger Refuge (photo: 12.05.2019)

As reported in the last blog, fresh snow is swiftly weakened when the weather improves. This is due to radiation energy, which is far greater than in deep winter. We are currently observing numerous avalanches in the mountains for that reason. These are generally loose-snow, in isolated cases glide-snow avalanches.

Loose-snow avalanches in the Northern Massif (photo: 17.05.2019)

Glide-snow avalanche in the Northern Massif (photo: 11.05.2019)

As regards slab avalanches, the explanation in the last blog still holds true. We assume that weak layers exist at high altitude which can be triggered due to danger pattern 4 (cold on warm). However, due to a lack of current snowpack analysis in the areas where slab avalanches are likeliest, based on dp 4, there are no further details to be reported.
In addition. following fresh snow one needs to focus attention on other potential weak layers: loosely-bonded fresh snow covered by snowdrifts; graupel; surface hoar in shady terrain adjacent to ridgelines (Nigg-Effect).

Frequent at this juncture of the season: graupel. Here in Defereggental. Graupel can form a weak layer whenever it covers a centimetres-deep layer. Central East Tirol  (photo: 15.05.2019)

En route near the Franz-Senn Refuge. Just like in deepest winter!

It will be awhile before the high-alpine pasture roads are free of snow...  Tux Alps (photo: 02.05.2019)

Warned often this year: do not underestimate the danger of cornices!  Silvretta (photo 01.05.2019)

Clearly displeased at the still snow-covered meadows: marmottes (in foreground). Silvretta (photo: 01.05.2019)

Friday 10 May 2019

Above average snow depths in the mountains – Avalanches still threaten

Winter still reigns in the mountains

Since the end of April, extremely variable, moist and unseasonably cold weather conditions have prevailed.

An atypical “melting display” for this juncture of the season: increasing snow depths in May at 2060 m altitude in the Tux Alps. In addition, the plummeting temperatures at the end of April are visible, including subsequent, highly variable weather.

The overall snow depths in Tirol’s mountains are above average for this juncture of the season.

A typical picture of Tirol: lush green in the valley, satin white in the mountains.

For comparison: a picture from the Lienz Dolomites in East Tirol  (photo: 07.05.2019)

Fresh snow reacts very rapidly to diffuse radiation and rising temperatures in this season. For that reason, over the last few days numerous loose-snow avalanches were observed releasing from rocky terrain and glide-snow slides and avalancahes over grass-covered slopes which were already bare in April and have now been blanketed in deep snow.

Loose-snow avalanches in “Inner Floiten Valley” in the Zillertal Alps (photo: 07.05.2019)

In the very brief time windows, the true snow fans were able to enjoy fantastic powder-snow adventures.

No, not an error. This photo was taken on 7 May, showing the ascent tracks towards the Marchreisenspitze in the Kalkkögeln...

...a similar photo from 5 May, in southern East Tirol, en route to the Golzentipp.

Wintery character persists

According to weather forecasts of ZAMG, conditions can be expected to remain variable and unseasonably cold. Tomorrow, Saturday the 11th of May, a cold front will arrive, bringing hefty rain showers, isolated thunderstorms and intensifying winds. The snowfall level will descend to intermediate altitudes, it is expected to lie between about 1000 m in northern regions and at 1400 m on the Main Alpine Ridge on Sunday.

In the mountains it will remain wintery.

Caution: avalanches

Following the expected snowfall, we will be able to observe a very similar pattern, compared to what has happened with recent snowfall: numerous naturally triggered loose-snow avalanches, increasingly frequent slides over grass-covered slopes. Whoever is en route at high altitudes and in high alpine regions needs to expend special care towards the freshly-generated snowdrift accumulations in the regions where precipitation is heavy, especially in very steep terrain adjacent to ridgelines. The weak layer will tend to have graupel in it, as can be deduced from weather forecasts, as well as covered powder snow. Surface hoar near ridgelines (Nigg), particularly in shady ridgeline terrain cannot be ruled out, but will probably be eliminated by wind impact before it becomes a real threat.

Comparably more dangerous are the faceted weak layers which have formed since the end of April as a result of the danger pattern cold-on-warm. They are now covered over by deeper layers of bonded snow and continue to be prone to triggering.  We assume, based on our own observations and incoming reports, this will apply to altitudes above about 2700 m. Initially, rather the shady slopes will be touched, with increasing altitude then to an increasing degree also west-facing, east-facing and south-facing slopes. This is a treacherous, not-to-be-underestimated threat of slab avalanches, especially because the fracture zones are area-wide and avalanches ultimately can grow to dangerously large size for backcountry skiers.

Slab avalanche in “Inner Floiten Valley” in the Zillertal. North-Northwest 2700 m (We received additional reports of avalanches on 7 May from Main Ridge NE at 3000 m, E at 2900 m and SE at 3150 m). (photo: 07.05.2019)

Thursday 2 May 2019

Winter just doesn’t want to give up...

Onset of winter at the end of April, short improvement at the beginning of May, and then winter will be back again:

Following heavy foehn impact, winter struck again on 26 April.

Lots of fresh snow in some parts of Tirol

The southern regions won the prize: between Friday 26.04 and Monday 29.04, there was 75 cm of fresh snow registered. Strong winds were blowing in the heights.

Onset of winter at the end of April: above Lienz in East Tirol (photo: 28.04.2019)

Wind-transported snow from previous days on the Carnic Ridge (photo: 01.05.2019)

Southern Ötztal: the start of the bad-weather phase with lots of precipitation and unseasonably low temperatures, some heavy wind impact. On 1 May, improvements, rising temperatures, but with increasing humidity.

And now, at the beginning of May, the ZAMG weather forecasters predict another outbreak of winter. In wide-ranging parts of Tirol, up to 50 cm of fresh snow is anticipated in the heights. Plummeting temperatures will bring snowfall down to low lying areas. Strong winds are expected over widespread areas.



Effects of the anticipated fresh snow on avalanche danger levels:

First, let’s have a look at the current situation: at high altitudes there are still above average masses of snow for this juncture of the season, while spring long ago made its entrance in low lying areas.

View of Serles from Navistal in the Tux Alps (photo: 02.05.2019)

Avalanche releases are currently limited to small loose-snow avalanches, mostly triggered by external impulses, isolated glide-snow avalanches and isolated slab avalanches (the latter especially in high alpine regions at present - 2nd May).

Loose-snow slides in the Silvretta at the end of April (photo: 01.05.2019)

Avalanche release initiated by a breaking serac in the southern Ötztal Alps (photo: 01.05.2019)

These avalanches were artificially triggered by explosives at the end of April. (photo: 01.05.2019)
The winter is fulfilling all wishes with regard to snow quality: just recently there was terrific powder snow in shady terrain at high altitudes, in many places on 1st and 2nd of May, even corn snow was to be had.

Descent from Mittlere Sonnenkogel in the southern Ötztal Alps (photo: 01.05.2019)

Due to a brief interim of very dry air, particularly on 1 May, there was corn snow well into the afternoon.
Tux Alps (photo: 02.05.2019)

The low number of registered avalanches and stability tests showcase a very favourable situation. Only in high alpine regions does the danger pattern cold-on-warm (dp.4) threaten in some regions starting on 26 April, where a weak layer has formed in the surface layers. Reports of fresh releases come mostly from the regions along the Main Alpine Ridge where recent snowfall has been heaviest, especially on very steep, sunny slopes at 3000-3300 m, also adjacent to ridgelines.

Snow profile, north, from 2 May in the Tux Alps: the sequence of crusts and softer layers is visible near the surface. Stability tests show stable layering. Fractures could not be propagated. The picture about 1000 m higher up is quite different, particularly on sunny slopes where the snowpack previously was moist or wet and was covered by cold, fresh snow at the end of April. Faceted crystals between crusts were probably the cause of avalanche releases involving persons.
Weak layers near the surface at high altitude will probably also be the main problem in the coming snowfall. In addition, the loosely packed fresh snow could generate a weak layer for a brief interim if it gets blanketed over by snowdrifts.

As was observed last week, fresh snow can glide on grass-covered slopes, especially when there is ample snowfall on bare ground.

Gliding snowslides from the end of April. Similar things can be expected this coming weekend. (photo: 02.05.2019)
To sum up, winter is not yet over. Avalanche danger still needs to be given serious consideration, apart from other mountain risks.