Reports are coming of more than 130,000 homes, businesses and farms without power after Storm Ellen swept over Ireland last night. Some significant damage was left in its wake. Ellen’s impact also spread across Northern Ireland, Wales, southwestern England, and Scotland. Destructive winds up to 180 km/h were reported just off the coast of southern Ireland!

Peak wind gusts across Ireland and the UK. Graphics: Meteociel
 

Pressure analysis

 

Actually, Storm Ellen was, before hitting Ireland, classified as a so-called “weather bomb” or bomb cyclone. Such cyclone is characterized by an explosive/rapid intensification led by explosive cyclogenesis process. It such systems, the air pressure drops by more than 24 millibars in the 24-hour period. Pressure dropped for nearly 30 mbar with Ellen. Attached are the pressure analysis of Ellen traveling from the Bay of Biscay into and across Ireland.

North Atlantic surface analysis. Graphics: NOAA
 

Wednesday, 21 UTC analysis

 

Surface pressure at 21 UTC. Graphics: Meteociel
 

Thursday, 00 UTC analysis

 

Surface pressure at 00 UTC. Graphics: Meteociel
 

Thursday, 05 UTC analysis

 

Surface pressure at 05 UTC. Graphics: Meteociel
 

Storm Ellen has, later on, brought unseasonably windy weather across Wales as well.

Category 1 hurricane-force winds

 

As we can see from the sustained and peak gusts wind data from the oceanic buoy #62023, the average wind speed between 8 and 9 pm local time was around 133 km/h. This is a solid Category 1 on the Saffir-Simpson hurricane scale. Peak gusts reached 180 km/h minutes later!

Buoy #62023 data. Graphics: Meteociel
 

Such winds can only be possible with the sting jet wind maximum. A sting jet is a relatively localized jet of rapidly descending cold air inside a deep extratropical cyclone. Sting jets are associated with the strongest and most damaging windstorms and cause extremely severe hurricane-force winds.

What exactly is the sting jet?

 

A sting jet phenomenon is a narrow zone of strong winds, originating from within the mid-tropospheric cloud head of explosive cyclogenesis.
 
Winds are enhanced further as the jet descends, drying out and evaporating a clear path through the precipitation. The evaporative cooling leads to the air within the jet becoming much denser, causing the acceleration of the downward flow towards the tip of the cloud head when it wraps around the cyclone center.

Example of sting jet on the North Atlantic. Graphics: Vedur

 

 

Windspeeds in excess of 90 mph (150 km/h) are often associated with the sting jet. This cloud, hooked like a scorpion’s tail, gives the wind region its name the “sting jet”.

140-180 km/h along the southern Ireland

 

Peak gusts measured along the southern Irish coast and on the oceanic buoys ahead of the coast last night:

180 km/h at the Buoy #62023, Ireland
144 km/h at the Roche’s Point, Ireland
113 km/h at the Shannon Airport, Ireland
108 km/h at the Cork airport, Ireland
108 km/h at the Malin Head, Ireland
108 km/h at the Mace Head, Ireland
104 km/h at the Sherkin Island, Ireland

Ireland station data. Graphics: Meteociel
 

Peak gusts reports across Northern Ireland:

115 km/h at the Glenanne, Northern Ireland
100 km/h at the Thomastown, Northern Ireland
93 km/h at the Portuglenone, Northern Ireland

Peak gusts reports across Scotland:

151 km/h at the Cairngorm, Scotland
119 km/h at the Cairnwell, Scotland
115 km/h at the Bealach Na Ba No2, Scotland
112 km/h at the Glen Ogle, Scotland

Peak gusts reports across Wales:

128 km/h at the Capel Curig, Wales
105 km/h at the Pembrey Sands, Wales
100 km/h at the Aberdaron, Wales

Peak gusts reports across southwestern England:

109 km/h at the Buoy #62107, England
89 km/h at the Cult Rose, England
87 km/h at the Camborne, England

Sting jet visible on satellite

 

We can see a rather textbook feature on the satellite. Sting jet was clearly evident given the very pronounced dry intrusion being forced into the center creating violent gusts. Usually, a cloud signature like a scorpion tail is seen.

Sting jet visible by satellite. Graphics: Vedur
 

 

 

Radar imagery revealed an impressive passage of the storm Ellen and its directly across Ireland, curving towards the Atlantic in the second half of the night.

Radar imagery of Ellen’s passage. Graphics: Met.ie
 

 

 

Reports during storm and aftermath

 


 


 


 


 

Severe winds and flooding warnings remain in effect today and tonight. Threats should gradually vanish on Friday as the main extratropical depression vanishes while drifting northeast. Stay alert!

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