Status:Finalized Material from: Fernando, Linus
Discussed in the following Daily reports:
Picture
1. Impact
On the 31 March 2015 a strong windstorm hit north-western Europe.the cyclones was named Niklas. At least 9 people were killed by the severe winds.
http://en.wikipedia.org/wiki/Cyclone_Niklas
http://www.bbc.co.uk/news/world-europe-32138213
2. Description of the event
Cyclone Niklas was the third cyclone over the last days in March, associated with a positive phase of NAO. The figures below show short forecasts (12h) of MSLP and precipitation. Niklas passed over northern Germany around 12z on 31 March.
MSLP and precipitation (12h forecasts)
The plot below show 24-hour maximum winds on the 31 March. Observations of more than 25 m/s in the gusts over land spread from Ireland to Poland.
3. Predictability
3.1 Data assimilation
3.2 HRES
The plots below show 24-hour maximum wind gusts valid 31 March and MSLP valid at 12z on 31 March.
24-hour max wind gusts 31 March
3.3 ENS
Cyclone feature 1km wind 600 km
Cyclone feature 1km wind 600 km |
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The plots below show the cyclone feature plots for maximum wind speed at 1 km height inside a 600 km radius for 31 March 12z.
The plots below show the EFI and SOT for winds gusts valid 31 March.
EFI and SOT wind gusts 31 March
The next plot shows the probabilities of exceeding 10-year return period of maximum wind gusts. The top-left panel shows the verification based on ERA Interim.
As mentioned in Section 2, the windy days in the end of March were associated with a strong positive NAO. The figure below shows the distribution of projections onto the positive NAO regime, averaged over 29-31 March. The strong phase of the NAO was well predicted 6-7 days in advance and all issued forecasts (up to 15 days in advance) was for a positive NAO.
3.4 Monthly forecasts
3.5 Comparison with other centres
4. Experience from general performance/other cases