The latest in a string of storms impacting western and northern Europe this winter rapidly intensified into a bomb cyclone as it swarmed Norway this week, strengthening into one of the strongest storms to hit the country in 30 years.
Storm Ingunn, named by the Norwegian Meteorological Institute, intensified by around 35 millibars over 24 hours as it passed the Faroe Islands, several hundred miles north of Scotland, while racing in the direction of Scandinavia. Already a strong storm before the process, it easily made bomb cyclone status, which requires about 24 millibars of intensification over the course of a day.
“Ingunn is one of the strongest storms to hit Norway in 30 years,” wrote Copernicus EU, a wing of the E.U. Space Program, in its wake Thursday.
Tens of thousands were left without power in Norway, according to local media. Train, air and road travel has also been disrupted across the region. The longest delays and most flight cancellations over recent days were in airports across Europe, including Oslo and Helsinki.
The central pressure dropped to an incredible 944 millibars, which is on par with the central pressure of a strong hurricane in the tropics.
Ingunn was named when red alerts were hoisted for much of Norway’s coast as it approached Scandinavia.
“From Wednesday afternoon to Thursday morning, a hurricane is expected on the coast,” warned the NMI.
Wild winds and massive waves
Even for a region used to intense windstorms, Ingunn is something else.
Norway set a record for average wind speed during the pre-dawn Thursday, according to the NMI. A maximum of 122 mph (54.4 meters per second) was observed in Sømna-Kvaløyfjellet, on a hillside along the northern coast. Gusts as high as 140 mph were reported there.
Farther inland in the mountains, at around 3,500 feet in Stekenjokk, Sweden also provisionally set an all-time wind speed record with a 10-minute average of 115 mph (51.8 meters per second), according to Mika Rantanen of the Finnish Meteorological Institute.
On the Faroe Islands, a gust of 155 mph was reported by a private weather station in Heltnin amid other gusts of 120 mph or so. Scotland saw a peak gust of 106 mph in Aonach Mor, a mountain in the highlands.
Gusts of 80 to 110 mph-plus were widespread in Norway, with the strongest near the coast and in the north. Most of Sweden and into Finland also observed gusts of 50 to 60 mph or greater.
Typically, the strongest winds are not directly observed by weather stations, but some additional gusts from government locations include:
114 mph at Heidrun oil field, Norwegian Sea108 mph at Vagar Airport, Faroe Islands93 mph in Fornebu, Norway (just southwest of Oslo)91 mph in Leknes, Norway87 mph in Tonsberg, Norway83 mph in Røst, Norway80 mph in Sykkylven, Norway78 mph at Sumburgh, Scotland
Shoreline and harbor areas were slammed with damaging winds that produced dangerous seas amid a deafening roar.
Near-shore waves in the Norwegian Sea were as high as 65 to 85 feet, according to Kairo Kiitsak, a meteorologist from Estonia. Waves as high as 30 feet were expected along shorelines through Thursday.
Other impacts from Ingunn also continued Thursday across parts of the region, including northern Finland, where a red alert was in effect for snow and high winds.
It is likely that a “sting jet” enhanced the swath of extreme wind from near the Faroe Islands to the coast of Norway.
Sting jets form in the most powerful mid-latitude cyclones. While they do not happen in all storms, they are a relatively common aspect of low-pressure areas that hit Europe. They have been part of some of the continent’s most memorable events, like the Great Storm of 1987.
As a storm intensifies rapidly, cold air from the jet stream — sourced miles above the surface — can be entrained into the frontal structures surrounding the low center. As the jet stream wind gets drawn in and pulled to the surface, wind speeds escalate further.
This wind maximum will occur near the tip of the wraparound “comma head” that develops with mature storm systems. Sting jets tend to occur when the storm is reaching its peak intensity and they typically last only a few hours.
Studies have shown that sting jets may become more common in a warming climate.
Ingunn comes on the heels of recent bout of storms hitting western and northern Europe. It was the fourth named during January, including three that were named by the United Kingdom’s Met Office.
Met Office has named 10 storms this season, the most to date since the convention became official in 2015-2016, and just shy of the full-winter record of 11 in that season.
While much of the central and southern portion of Europe has been dealing with unusual warmth to start the year given the persistent storm track well to the north, signals point to colder and stormier risks growing continent-wide heading deeper into February.