Status:Ongoing analysis Material from: Linus, Fernando, Ervin
Discussed in the following Daily reports:
http://intra.ecmwf.int/daily/d/dreport/2016/01/28/sc/
http://intra.ecmwf.int/daily/d/dreport/2016/01/29/sc/
http://intra.ecmwf.int/daily/d/dreport/2016/02/01/sc/
1. Impact
On 29 January a severe windstorm swept from northern British Isles to Norway. It was named as Gertrude and in Norway as Tor. The storm managed to break the all-time wind speed measurement record setting a new value of 48.9 m/s at Krakenes lighthouse north of Bergen on the coast. Here are an English and a Norwegian article. The second one has a long list of the observations (wind speed and gust).
http://www.newsinenglish.no/2016/01/30/dangerous-storms-winds-set-record/
http://www.yr.no/artikkel/_-har-aldri-for-opplevd-slik-pagang-1.12778465
2. Description of the event
The figure below shows the warnings for this event. Red warnings were issued for the Shetlands and southern half of Norway.
The plot below shows 24-hour maximum wind gusts for 29 January 12z to 30 January 12z.
The plot below shows significant wave height from one buoy west of Norway. (from magicseaweed.com)
3. Predictability
3.1 Data assimilation
3.2 HRES
24-hour wind gusts (29 Jan 12z - 30 Jan 12z) for o-suite (observations in the first panel):
Same as above but for e-suite:
3.3 ENS
The series of plot below shows cyclonic features where the colour indicates the maximum wind at 300 km radius.
The plot below show the EFI and SOT for wind gusts valid 29 January from 00z forecasts.
To see it more quantitatively the evolution of the forecasts, the values for a box around the strongest windgusts observed as [64.5, -5, 56.5, 9.5] including most of Scotland, the Shetland Islands and SW of Norway. The following values are area averages over this box from the HRES, the ENS-control and the Q0, Q25, Q59, Q75 and Q100 of the ENS. The observation is unknown, but the shortest range forecast's 34-35 m/s looks realistic based on the observed wind gust values. The HRES even up to the 00z run on the 24th looks pretty high, only slightly less windy than the latest run on the 29th. In earlier runs the values started to decrease bit faster. All in all the model was able to get continuously closer to the very high values without any major jumpiness, at least on this larger areal average scale. In terms of difference between the operational and e-suite they look very similar. The only maybe systematic difference I can see is the median of the ENS where the e-suite looks higher than the median of the oper forecasts almost in all runs making it slightly better.
3.4 Monthly forecasts
3.5 Comparison with other centres
4. Experience from general performance/other cases