The example below details an event that happened in northwest England. It would have generated a yellow warning of rain with the new warning service.
Weather situation on 21 January 2008
An area of low pressure with bands of heavy rain moved eastwards from Northern Ireland to Northern England. It was the latest in a series of rainfall events that had affected the area in the preceding weeks. Although rainfall amounts were relatively modest, impacts occurred as the result of already almost saturated ground and raised river levels.
Combined rainfall totals for 20 and 21 January included:
|Rochdale (Greater Manchester)||41mm|
This particular example has been chosen to illustrate what can happen when a relatively modest amount of rain falls on land that has been brought to virtual saturation by well above average rainfall in the preceding weeks. The period leading up to the event had been very wet with roughly twice the average rainfall for January.
A flooded street
Based on the new warning system the following assessments would have been made:
This would have resulted in a yellow warning for rain: