Evaluations by the ZAMG Weather Service show that meteorologically speaking this has been one of the warmest and driest in history. “In Innsbruck there has been 27 millimetres of precipitation (72 percent less than average) up till now this spring. It was drier than this only three times since the year 1877, when measurement-taking began: in 1879 (12 millimetres), 1946 (24 millimetres) and 1976 (24 millimetres).”
Current weather goes hand in hand with the dryness: predominantly sunny. Precipitation was registered, if at all, only in single-digit mm, most of it on Sunday, 19 April and Monday, 20 April.
 |
| The tiny amounts of precipitation in Tirol, 19 - 20 April. |
 |
| Inzinger Alm measurement station in the Stubai Alps is now bare of snow. The tiny blue bumps in the upper graph show the precipitation last week. |
Effects on the snowpack
The snowpack is becoming moister, even at high altitudes.
Let’s stick to precipitation for a minute: even if it was minor, the air moisture on these precipitation days was quite high, seen in absolute terms. The snowpack “sucked in” the moisture of the air like a sponge and rapidly became moist or wet. That is easy to recognize at the automated weather stations where there is still snow and where snowpack surface temperature, air temperature and air moisture are measured.
 |
| What is most significant is the thoroughly wet snowpack, visible through the flat snowpack-surface temperature at about 0°C. An additional important factor is the thawing point, which at times even was above 0°C. |
Highly significant is the extent to which the snowpack became thoroughly wet last week, particularly on north-facing slopes at high altitudes, and was thereby weakened.
Snow depths decreasing
The snow diminished further this week, on the one hand through melting, on the other, through sublimation (direct transformation from solid to gaseous form). The former occurred on 18.04 and 21.04 when the air was moist; the latter on 17.04 and 22.04 when the air was very dry.
 |
| The snow didn’t just decrease, in some places it touched a record-breaking minimum over long measurement periods. |
 |
| For comparison: snow depth on Furkajoch (Bregenzerwald) on 8 March 2020... |
 |
| and the same spot, today, on 23.04. |
A collage of photos from the foto-webcam.eu of this station, showing comparative shots from last winter, is also interesting:
 |
| Highly varied rates of snow decrease last winter |
 |
| Another aspect of snow-decrease (photo: 22.04.2020) |
"Summertime corn snow"
The repeated freezing-and-thawing of the snowpack has led to transformation of the snow towards stable summertime corn snow. This is the case at intermediate altitudes in all aspects, insofar as there is still snow at that altitude, and particularly on sunny slopes at somewhat higher altitudes.
Briefly higher avalanche activity on 19.04. and 20.04.
The thoroughly wet snowpack during the days with some rainfall plus cloudy nights subsequently led to higher avalanche activity. Typically, they were nearly all loose-snow and glide-snow avalanches; in very isolated cases, small slab avalanches.
 |
| Loose-snow avalanches on Nederkogel, Ötztal, photographed on 20.04 at 4:30 pm |
 |
| Additional loose-snow avalanches on Nederkogel, Ötztal, photographed on 20.04 at 6:30 pm, just two hours later |
 |
| Deposits from loose-snow avalanches, Zemmgrund (photo: 22.04.2020) |
 |
| Similar situation, Kalkkögeln (photo: 21.04.2020) |
What’s next?
Following the moist days, the air became much drier, and avalanche danger is again subject to a minor daytime danger curve. As the air masses destabilize and more clouds move in during the next few days, the air will moisten from region to region, the situation deteriorate somewhat.
 |
| Danger map for 24.04.2020 |
