Sting jet signature associated with a high wind event in Scotland (storm Ulli, 3 January 2012)

by Scott Bachmeier (CIMSS)

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A rapidly intensifying mid-latitude cyclone was responsible for a high wind event as it moved over Scotland on 3 January 2012. Meteosat-9 WV7.3 images (below) revealed two notable signatures: (1) the formation of a pronounced area of warm/dry water vapor brightness temperatures (bright yellow to orange color enhancement) over the open water north of Ireland, which indicated a strongly forced region of rapidly descending middle-tropospheric air, and (2) a classic sting jet** signature (Monthly Weather Review | Wikipedia) which then moved eastward across Scotland. Just to the south of the sting jet signature, a wind gust of 78 knots was recorded at Glasgow at 08:20 UTC, followed by a wind gust of 70 knots at Edinburgh at 08:50 UTC. There were additional reports of wind gusts in excess of 87 knots at non-METAR sites in Scotland. A comparison of 1-km resolution NOAA-19 VIS0.6 channel and IR11.0 channel (animated GIF, 1057 KB, source: CIMSS) images at 12:54 UTC showed the structure of the cyclone as it was centered over the North Sea between the British Isles and Norway.

Amendement (Theo Steenbergen, 16 January 2012)

In the strong westerly flow, a cold front rapidly moved across the North Sea, passing the Dutch coast in the afternoon of 3 January (see Met-9 HRV Animation, 10:00-14:30 UTC, animated GIF, 5718 KB). The front was accompanied with a squall line, visible in the radar image as a narrow band of intense rain. The coastguard ('Rijkswaterstaat') reported a so called meteotsunami at the coast at Ijmuiden, with a sea level change (rise and fall) of over 1.5 meters in 30 minutes.

**Definition of a sting jet from Browning (2004): "The most damaging extratropical cyclones go through an evolution that involves the formation of a bent-back front and cloud head separated from the main polar front cloud band by a dry slot. When the cyclone attains its minimum central pressure, the trailing tip of the cloud head bounding the bent-back front forms a hook which goes on to encircle a seclusion of warm air. The most damaging winds occur near the tip of this hook–the sting at the end of the tail."

References

Browning, K.A. (2004): The sting at the end of the tail: damaging winds associated with extratropical cyclones. Q. J. R. Meteorol. Soc. 130: 375-399.
Martinez-Alvarado, O. (2010): Sting Jets in Simulations of a Real Cyclone by Two Mesoscale Models. Monthly Weather Review, 138, 4054-4075. DOI: 10.1175/2010MWR3290.1

Meteosat-9 WV7.3 Image
Met-9, 3 January 2012, 06:00 UTC
Channel 06 (WV7.3)
Full Resolution (GIF, 101 KB, source: CIMSS)
Animation (02:30-09:45 UTC, animated GIF, 3519 KB, source: CIMSS)

Meteosat-9 IR10.8 Image
Met-9, 3 January 2012, 06:00 UTC
Channel 09 (IR10.8)
Full Resolution (PNG, 723 KB)
Animation (03:00-06:00 UTC, animated GIF, 4073 KB)
Animation (02:00-23:00 UTC, MPG, 13757 KB)

Metop-A ASCAT Winds
Met-9 3 January 2012, 12:00 UTC
Channel 05 (WV6.2) and Metop-A ASCAT winds
Full Resolution (PNG, 420 KB, source: EUMeTrain)
4 January 2011, 00:00 UTC (PNG, 344 KB, source: EUMeTrain)
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