WeatherBlog 21 2020/21 | Accompanying blog to the April alarm

Current situation and outlook

The details on the snowfall can be found in the PowderGuide.com. Today (Wednesday) it is still cloudy in the north and it continues to snow, although not necessarily everywhere, but often more as showers that occur here and there. Accordingly, the amounts of fresh snow in a small area will vary considerably.

From tomorrow (Thursday), it will gradually become sunnier. This will happen faster in the western Alps than in the northeast, where clouds may continue to accumulate for longer. It will remain relatively cool for the time of year, but will become milder as the day progresses. The very cold air masses that are still affecting us today will be pushed aside and warmer air will flow in from increasingly westerly directions. The low pressure in the north will remain for the time being, but the center will shift slightly to the west so that the Alps will slide more to the front of the trough than at present. While Friday is likely to be very sunny everywhere in the morning, clouds will soon gather again from the west. The current will turn from west to SW over the course of Friday and the weekend is likely to be characterized by south föhn in the north and accumulating precipitation in the south, although it is still unclear how heavy the latter will be.

When, as is currently the case, cold air from the still wintry Arctic Ocean flows southwards and meets the comparatively warm land masses, a strong vertical temperature gradient sets in. The ground is warm, at altitude it is very cold. This is virtually the opposite of the inversion known from high winter, where the cold air hangs like a large lake in the valleys and cannot rise. While an inversion is a very stable stratification (hardly any vertical air exchange), the current situation is very unstable. This means that warmer air close to the ground tends to rise. The higher it rises, the more it cools down. At some point, the water vapor contained in the air parcel condenses and turns into clouds and then snow showers, as we are currently experiencing.

However, a few other factors are also important for the May flowers. If they bloom too early due to the summery March temperatures, frost in April is obviously not good for them. The current weather is endangering the fruit blossom wherever the trees are already in bloom. In some cases, the always spectacular-looking frost irrigation has been resorted to.

Depending on the region, it is also very dry - this affects parts of Germany, for example, that do not benefit from the congestion of the mountains. This considerable deficit cannot be compensated for by a few April showers and will probably accompany agriculture throughout the year. There has also been little to no precipitation in the Southern Alps for a long time; skiers and bodies of water have to make do with the existing snow cover. We're keeping our fingers crossed for supplies at the weekend!