Prolog: The annual “weather summit” took place in Tyrol in 2017. On three days the weather summit is an international meeting point for meteorologists and TV presenters with the background “weather and climate”. For 2017, the Obergurgel-Hochgurgel region in the Ötztal valley was chosen as the venue. At the event I talked to Oliver Schwarz, the managing director of Ötztal Tourism. When he heard that I was riding a racing bike and had already taken part in the Ötztal 2016, the idea was born that I could act as a “weather girl” at the Ötztal 2018 cycling marathon. Because what is more authentic than a meteorologist, who has to “suffer through” his own weather forecast later.
The weather was anything but rosy for an alpine bike marathon. Already one week before, the weather models for the race weekend announced an almost wintry weather in the mountains. Unfortunately the forecast remained persistent: A trough, which reaches over Central Europe to Italy and from which a drop of cold air is strangled at the weekend, should shape the weather of the Ötztal track. The days before the race, it rained frequently and partly in streams and in the higher altitudes there was – like the day before on the Timmelsjoch – snowfall. According to models, the rainfall should decrease from Saturday to Sunday morning and the Sunday morning should become more friendly for a while before a new labilization starts in the course of the day. In these weather conditions, however, only one thing is clear: everything can be completely different. Well, what do you do as a meteorologist? Stand up and say: no matter what I say now, it can arrive completely different? No, nobody wants to hear that. So you dig through the models and sound out the limits of the weather situation in order to assess extremes correctly and select the weather with the greatest probability for the forecast. Already at breakfast on Saturday at the hotel I unpacked my laptop to analyze the latest model calculations. In the early afternoon the press meeting was scheduled at the James Bond World of Experience, 007 Elements. The building is located at 3040 meters above sea level inside the Gaislachkogl. Above everything was wintery and the journalists waited eagerly for my presentation on the weather forecast. Although I emphasized the natural uncertainty of the weather situation, the probability for snowfall was extremely low, because both temperature and dew point only allowed rain as a possible aggregate state for precipitation.
After the press conference I had a short time to get all my stuff ready for the race before I called up the new model data to make possible changes to the forecast for the driver briefing. In the new model runs the different weather models drifted a bit apart. It was unclear how long the nightly rain would continue into the morning. To make ONE prediction at the Ötztal Bike Marathon is almost impossible, considering that the participants’ driving time differs by up to 7 hours towards the end. So the front field can experience a completely different weather than the slower part of the drivers. Since the probability of rain for the 2018 race was not less than 30 percent at any time or on any section of the track, but much higher, one could have set a rain symbol everywhere as a weather symbol for a forecast. But that would have drawn too gloomy a picture, because it was quite probable that the riders would be completely dry throughout the day based on the forecast data. In the morning rain was still possible, but it should go away. And then the probability for showery rain and thunderstorms rose again in the course of the day.
Dominic Kuen (left)
No question about it, the weather in the Alps can vary completely from valley to valley and from mountain to valley. Knowledge is what virtually everyone does, only so really consciously we only do it when we experience it ourselves. At the Ötztaler 2018 this was shown to the participants in a wonderful way. The start was dry and also the descent to Ötz and the foot of the Kühtai had only rarely wet road sections to offer. The lowest probability of rain was estimated by the models for the later morning towards Innsbruck. And at the weather station in Innsbruck it was dry most of the time. Only between 10 a.m. and 11 a.m. CEST a meager 0.1 litres per square metre were registered. Between Innsbruck and Kühtai, on the other hand, it had rained heavily on the descent and the evaporation cooling had reduced the temperatures to 4 degrees in the upper part of the Kühtai. At the Brenner the first showers already started in the morning and not at noon, so that especially the fast cyclists got wet. For a meteorologist, these deviations from the model forecast are not surprising given the weather conditions. Looking back, the weather forecast must seem like a mockery to a racing cyclist, especially when he is exposed to wetness and cold. The afternoon, on the other hand, was not very spectacular. At times it was friendly with sunshine, before more showers and thunderstorms came from Italy.
Looking back, as a meteorologist I have to say that the weather situation and the resulting weather were absolutely identical and the forecast of the models – regarding the general conditions with weather situation and forecast region “Alps” – did not overstretch the expected uncertainty. As a participating cyclist I would call the whole thing merciless.
