Storm Angus

Storm Angus

19 November 13:00 UTC–21 November 2016 13:00 UTC

Storm Angus
Storm Angus

Storm Angus, the first named UK storm of Autumn 2016, brought high winds and flooding to southern parts of the country.

Last Updated

14 November 2020

Published on

19 November 2016

By Djordje Gencic, Jochen Kerkmann, Phil Nolan and Sancha Lancaster (EUMETSAT) and HansPeter Roesli (Switzerland)

Storm Angus brought wet and windy weather to England and Wales on 20 November, with 59mm of rain recorded in Exeter, Devon and maximum gusts of 81mph at recorded in Langdon Bay, Kent (Credit: Met Office).

 Airmass RGB, 20 November 05:00 UTC
Figure 1: Airmass RGB, 20 November 05:00 UTC
 
 Metop-B Natural Colour RGB, 20 November 09:27 and 11:07 UTC
Figure 2: Metop-B Natural Colour RGB, 20 November 09:27 and 11:07 UTC

This autumn's first Atlantic storm developed near the Bay of Biscay and moved towards the coast of Bretagna and UK.

The Meteosat-10 Airmass RGB imagery, Figure 1, above right, and animation clearly shows the storm as it passed over southern parts of the UK overnight 19/20 November, bringing torrential rains to many areas.

A very clear hook can be seen on the Airmass image from 05:00 UTC (Figure 1) this is indicative of strong convection.

The storm system can also be seen on the Metop-B Natural Colour RGB composite of two swathes, 20 November 09:27 and 11:07 UTC (Figure 2) sitting over the south-eastern parts of the UK.

Sometimes it is better to use colour enhanced images, instead of grayscale. In this specific case it is easier to see different shapes using the water vapour channels, especially small scale eddies, swirls, etc.. The water vapour imagery also shows the existence and movement of dry air from the upper troposphere and lower stratosphere — important for the future development of mid-latitude storms.

On the Meteosat-10 Water Vapour animation, the dry air appears as the black/brown coloured areas.

On its front side the convective system had a strong southwesterly flow, transporting a lot of unseasonably warm/mild air from Africa over central and eastern Europe.

This strong flow also triggered the formation of lee clouds on the northern side of Pyrenees, shown as the brighter areas of cloud on both the Airmass and Severe Convection images in Figure 3. On the Severe Convection RGB the bright yellow area indicates the presence of small ice particles in the lee clouds.

At the same time, on the rear side of the cyclone, in a northerly flow, cold and drier polar air arrived from higher latitudes.

On 21 November, with the southerly flow, strong foehn were observed in Switzerland, Austria and southern Germany. At the southern end of the lake of Lucerne in Switzerland the average wind speed for 48 hours was 50 km/h (31 mph), with gusts above 100 km/h (61 mph), while at Jungfraujoch in the Bernese Alps (3580 m) the average wind speed was 100 km/h (61 mph) with maximum gusts of 163 km/h (101 mph). In Salzburg the temperature reached 21 °C.

Image comparison

Severe Convection RGB, 21 November 12:00 UTC compare1
compare2
 

Figure 3: Comparison of Meteosat-10 Airmass and Severe Convection images.