The example below details an event that happened in southern England. It would have generated an amber warning of fog with the new warning service.
A large area of high pressure became slow moving for several days over central, southern and south-eastern England. This allowed widespread and persistent, locally freezing fog to form across much of this area, which in some locations persisted for three to five days.
In many places, visibility was reduced to below 100 metres and in some cases to below 30 metres. Transport hubs, including the major London airports in the South East were particularly badly affected.
Had this weather type been a one-day event it may well have been a yellow event. However the longevity of the fog, once established, means this would have been an amber event.
An Aircraft in the fog
Based on the new warning system the following assessments would have been made:
This would have resulted in an amber warning for fog: