Status:Ongoing analysis Material from: Ivan, Linus
Discussed in the following Daily reports:
http://intra.ecmwf.int/daily/d/dreport/2015/12/07/sc/
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1. Impact
Storm Desmond, the fourth named storm of the season, caused severe flooding, travel disruption and a power outage across northern England and parts of Scotland. Flooding and travel disruptions were reported from Ireland as well. Cumbria in NW England is one of the worst affected regions with more than 200 mm of rain in 24 hours recorded in that area. On Saturday, 5 December, UK Met office issued a red warning of heavy rain for Cumbria.
2. Description of the event
3. Predictability
3.1 Data assimilation
3.2 HRES
Both the O-and E-suite forecasts are similar with peak values of the rainfall of about 100 mm in 24 hours in Cumbria. The E-suite looks marginally better. The UKMO global model was a bit better in terms of precipitation amounts but generally all three forecasts were quite a lot below the observed peak values. It's worth mentioning that orographical enhancement of precipitation played a major role and the models picked well the highest amounts over the orographical barriers.
Much higher resolution MOGREPS picked much better the extreme values of precipitation compared to HRES. The maximum value of precipitation over Cumbria in MOGREPS is 202 mm/24h.
3.3 ENS
The EFI values were above 90% more than 3 days in advance. High values of the EFI and SOT show pretty well the potential of extreme rainfall in the affected areas. For the ENS the extreme rainfall values were lower compared to HRES.
3.4 Monthly forecasts
3.5 Comparison with other centres
4. Experience from general performance/other cases
5. Good and bad aspects of the forecasts for the event
- Underestimation of the orographic precipitation and overestimation in lee of the the hills