Case studies
Storm Desmond
Storm Desmond caused severe flooding, travel disruption and a power outage across northern England, parts of Scotland and Ireland on 5 December 2015. Cumbria in northwestern part of England is one of the worst affected regions with more than 200 mm of rain in 24 hours recorded in that area. Storm Desmond broke the United Kingdom's 24-hour rainfall record, with 341.4 mm of rain falling in Honister Pass, Cumbria. On Saturday, 5 December, UK Met office issued a red warning of heavy rain for Cumbria. The cyclone also led to flooding in southern Norway.
Orographical enhancement of precipitation played a major role in the event and the operational model of the ECMWF picked well the highest rainfall amounts over the orographical barriers. However, the forecast underestimated the peak values of about 100 mm in 24 hours in Cumbria and overestimated the precipitation amount in lee of the hills (Figure 1).
| Observations | Forecast |
|
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Figure 1: 24-hour precipitation amount (mm) between 5 December 6 UTC and 6 December 6 UTC, based on observations (left) and ECMWF operational IFS forecast (right). | |
Several experiments have been conducted with OpenIFS for this case with the aim to test the effect of starting date and forecast length, initial condition as well as spatial resolution to the forecast quality. The details of experiments are summarized in Table 1.
Table 1: Settings of the experiments achieved for Storm Desmond. | |||||
| Initial condition | Resolution | Starting date | Time step | Output frequency | |
|---|---|---|---|---|---|
| 1. | ERA-Interim | T255L91 |
| 2700 s | 3h |
| 2. | ERA-Interim | T639L137 |
| 900 s | 3h |
| 3. | ERA-Interim | T1279L137 |
| 600 s | 3h |
| 4. | ERA5 | T255L91 |
| 2700 s | 3h |
| 5. | ERA5 | T639L137 |
| 900 s | 3h |
- download from download.ecmwf.int/openifs/evalution
Storm Xavier
On the 5 December 2013 the cyclone swept from Scotland, over the North Sea and hit Denmark, Germany and Sweden. Problems were caused both by the wind and the following storm surge. The surged reached 6 metres in Hamburg for example and was the highest along the England east-coast for 60 years. In the aftermaths of the cyclone a blizzard hit Sweden. The cyclone was presented in the forecasts 8-9 days before the event and the forecasts indicated the very strong winds 3-4 days in advance.
Several OpenIFS experiments have been conducted for this case with the aim to test the effect of starting date and forecast length, initial condition as well as spatial resolution to the forecast quality. The details of experiments are summarized in Table 2.
Table 2: Settings of the experiments achieved for Storm Xavier.
| Initial condition | Resolution | Starting date | Time step | Output frequency | |
|---|---|---|---|---|---|
| 1. | ERA-Interim | T255L91 | 2700 s | 3h | |
| 2. | ERA-Interim | T639L137 | 900 s | 3h | |
| 3. | ERA5 | T255L91 | 2700 s | 3h | |
| 4. | ERA5 | T639L137 | 900 s | 3h |
Post-processing step
- how to prepare data for plotting
- precipitation.
Metview macros
- where they are, how to set them up .. etc