Fwd: [emergency-comment] Request for "polar low" as event term

Dear committee,
This is a request from the Norwegian Meteorological Institute to add "polar low" to the Event Terms List.

Polar Lows are small but rather intense lows that occur in the coastal Arctic regions during the winter season. They give a combination of gale or storm force winds (OET-221), heavy snowfall (OET-184) and snowstorm (OET-185) with rapidly changing weather conditions (incl OET-222), that if not headed can pose a severe threat both to the general public on land and to maritime operations. The consequences are widespread disruptions to road traffic, coastal ferries and air traffic. Because polar lows can deposit large amounts of snow, they give locally severely increased risk of avalanches (OET-018), which in recent years have been the main cause of fatalities due to natural hazards in Northern Norway. In northern sea areas polar lows will often give freezing spray (OET-091). In sea areas polar lows will often give high waves.

A Polar Low that affected Northern Norway on the 16th December 2022. This low gave 1 to 1,5 meters of snow locally on the Andøya and Senja islands.

Polar lows occur in most of the European maritime arctic, and are most common at the coast of Scandinavia north of 65 degrees north, but are known to affect all areas around the North Sea. While they are a maritime or coastal phenomenon, polar lows will still produce a significant amount of snowfall also further inland where the lows make landfall.

Wintery weather with snow showers and gale force winds is relatively commonplace in Northern Norway during the winter, and will normally not affect the public significantly. Polar lows however, are at the most intense end of the winter weather spectrum and will typically give stronger wind and more intense snowfall, and thus have a larger impact on coastal communities. For this reason MET Norway is issuing dedicated weather alerts for Polar Lows, adhering to the definition of the European Polar Low Working Group (EPLWG), but with the constraint that the 10m wind is expected to be above 21 m/s or severe gale force.

Relevant CAP categories are “Meteorological” and “Transport”. The most relevant grouping is "winter weather".

The broad term “polar low” collectively subsume a number of smaller events, as mentioned earlier. The term is used to service multiple user communities.

Tromsø, August 8th 2023
Gunnar Noer

References:
Polar Lows Explained: Barentswatch.no,https://www.barentswatch.no/en/articles/polar-lows-explained/

Stoll, P. J.: A global climatology of polar lows investigated for local differences and wind-shear environments, Weather Clim. Dynam., 3, 483–504, https://doi.org/10.5194/wcd-3-483-2022, 2022.https://wcd.copernicus.org/articles/3/483/2022/

Best regards,
Gjermund Haugen
Deputy head of Division for Forecasting Tromsø
Norwegian Meteorological Institute

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