The example below details an event that happened in Cumbria. It would have generated a red warning of rain with the new warning service.
Weather situation on 19 November 2009
The weather had been generally wet and disturbed for a number of weeks prior to this event with autumn rains causing increasing ground saturation and a seasonal rise in river levels. A south-westerly air stream brought very mild air across the UK during this period. As this mild, moist air arrived over the Cumbrian mountains, it resulted in exceptionally large amounts of rainfall over three to four days.
Rainfall totals across Cumbria for the period 0900 GMT on 17 November to 0900 GMT on 20 November included:
|High Snab Farm||401.4mm|
|Mickleden, Middle Fell||309.2mm|
|Grassmere, Tanner Croft||294.7mm|
|St Johns Beck||265.8mm|
The key feature of this event was the prolonged nature of the heavy rainfall over several days.
Floodwater flows under a bridge
Based on the new warning system the following assessments would have been made:
This would have resulted in a red warning for rain: