In autumn/winter 2015-16 the UK Met Office partnered with the Irish met service, Met Éireann, to run a pilot scheme naming autumn/winter wind storms with the potential to cause substantial impacts.  The names of the storms were chosen by the public.

Storms from the east form over the Atlantic and in the autumn/winter period can bring severe weather to the UK and Ireland. The UK and Irish met services found linking the weather warnings to a named storm was a success, so they also decided to do it in 2016-17.

Storm Angus captured by Metop B on 20/11/2016

Storm Angus captured by Metop B on 20/11/2016

Storm Angus was the first named storm of the period. It brought wet and windy weather to England and Wales on 20 November, with 59 mm of rain recorded in Exeter, Devon and maximum gusts of 81mph at recorded in Langdon Bay, Kent. Serious flooding as a result of the storm left thousands of homes in southeast England without power.

The storm developed near the Bay of Biscay and moved towards the coast of Brittany in France and on to southern parts of the UK. Warm and cold air colliding over the Atlantic Ocean to the west of the UK provided the seeds an area of low pressure to form. When this low pressure combined with the jet stream Storm Angus was formed.

RGB airmass Angus

Satellites watch the storm

Using satellite imagery it was easy to see the development and journey of this storm.  On the Meteosat-10 Airmass RGB imagery animation (MP4, 2 MB) the large white area moving across southern England is the storm as it passed over southern parts of the UK overnight 19/20 November, bringing torrential rains to many areas. The curve or hook on the Airmass image from 05:00 UTC (Figure 1) shows strong convection — a common feature of storms.

The storm system can also be seen sitting over the south-eastern parts of the UK on the Metop-B Natural Colour RGB. The image is actually two sets of images joined together, taken at 20 November 09:27 and 11:07 UTC (Figure 2). The cyan or turquoise colour of the clouds indicates these are ice clouds, so very cold and with strong convection.

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, (MP4, 4 MB) the dry air appears as the black/brown coloured areas.

 

Posted by Sancha Lancaster

Leave a reply

Your email address will not be published. Required fields are marked *