If you follow ski racing, you know that this Friday and Saturday should each have featured a men's downhill and Sunday a slalom on the famed Hahnenkamm in Kitzbuhel, Austria. Instead, the meteorologists won the day and the Saturday downhill and Sunday slalom were switched due to anticipated heavy snowfall on Friday night and Saturday.
Indeed the Saturday snow did materialize and Dave Ryder won Great Britain's first world cup race as he unleashed a great second run and the top skiers from the first run flailed in the difficult conditions.
It's GOLD for @daveryding in the Kitzbühel Slalom @fisalpine World Cup!!
— GB Snowsport (@GBSnowsport) January 22, 2022
BRITAIN'S FIRST EVER ALPINE SKIING WORLD CUP GOLD - laying down a marker for @Beijing2022 next month!
👏👏👏👏👏 pic.twitter.com/HVvz2ceaKE
Ryder learned to ski on plastic slopes in England and has been knocking at the door for a win for a long time. Great to see him get his first win at the age of 35, a day after Johan Clarey of France came in 2nd in the downhill at 41. I believe Clarey is the oldest skier to podium in world-cup history.
Getting back to meteorology, the snow was produced by a common eastern Alps storm type know as Nord Stau or northern blocking. These storms occur when there is a high pressure west of the Alps and low pressure to the east, resulting in moist, northerly flow directed towards the Alps. Often, the flow is stable and the low-level airmass is unable to surmount the massive Alpine barrier. As a result, the low-level flow is blocked and becomes westerly near the Alps. This can yield heavy snowfall upstream of the Alpine foothills and terrain near the northern Alpine Rim. Often there is a dramatic weather near the Alpine Divide, with dry conditions or even clear skies to the south.
This is precisely what happened today. I've provided a sketch below on the MODIS imagery from midday. Northerly flow over Germany to the north of the Alps and low-level westerly flow near the Alps, with a transition from cloudy and snowy near and north of the Alpine Divide to clear skies to the south.
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| Source: NASA |
Evidence for this flow pattern is apparent in the 1200 UTC sounding from Munich, which is about 50 km north of the Alpine foothills. The low level flow is westerly, but veers to northerly at about 900 mb, or 1000 meters above sea level.
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| Source: University of Wyoming |
Nord Stau can produce more in the lower terrain near the northern Alpine Rim than on the much higher Alpine Divide to the south. Below is the 6-hour difference in snow depth analysis for the region for the period ending at 5 AM local time this morning. Snowfall is clearly greatest near and along the Austrian-German border north of Kitzbuehel where peaks are generally around 1500-2500 meters high. Snowfall declines to the south along the Alpine Divide where there are many peaks over 3000 meters. Practically no snow fell south of the Alpine Divide.
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| Source: https://avalanche.report/ |
If you woke up this morning in Innsbruck, you could have elected to ski powder near the northern Alpine Rim or traveled through the Brenner Pass for sunny skies. Your choice.
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