Status Status:Ongoing analysisFinalized Material from: Fernando, Linus
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Discussed in the following Daily reports:
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http://intra.ecmwf.int/daily/d/dreport/2015/03/31/sc/ |
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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
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Cyclone Niklas was the third intense 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.
Gallery includeLabel mslp_an sort comment title 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
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Gallery includeLabel wg_hres sort comment title 24-hour max wind gusts 31 March
3.3 ENS
Gallery includeLabel dal_wind sort comment title Cyclone feature 1km wind 600 km
| includeLabel | dal_wind |
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| title | Cyclone feature 1km wind 600 km |
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.
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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
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