Status:
...
Finalised Material from: Linus, Mohamed, Fernando, Tim
Discussed in the following Daily reports:
...
http://intra.ecmwf.int/daily/d/dreport/2015/01/09/sc/
...
http://intra.ecmwf.int/daily/d/dreport/2015/01/12/sc/
1. Impact
| Excerpt |
|---|
On 9-10 January 3 severe |
cyclones hit north-western Europe. The first (named Elon -DE, Dagmar - DK) hit Scotland early on Friday 9 January with mean wind of 46 m/s and wind gusts up to |
63 m/s in Cairngorm and later hit Denmark and Germany. |
The evalution evaluation below is both for the Friday 9 January and Saturday 10 January.
Facts from: http://artikkel.yr.no/sa-sint-var-nina-1.12143639 and http://www.smhi.se/nyhetsarkiv/egon-sasongens-forsta-ordentliga-storm-1.83408
2. Description of the event
...
Gallery includeLabel mslp_12 sort comment title MSLP and precip 12-hour fc
Looking back at satellite imagery sequences for both Elon and Felix, and in both there was some evidence, from evaporating fingers of cloud head particulate, of sting jet activity, with model profiles, at least in 2-3 day forecasts, also supportive. For Elon sting jet activity and duration look to have been limited; Felix looked a bit more clearcut. The sequence below is probably after a short sting jet phase for Elon, given that the cloud head tip is already advancing around the cyclone, in 'hammerhead' format. So any strong winds associated were probably due to the 'cold jet' that typically follows.
3. Predictability
3.1 Data assimilation
...
Gallery includeLabel hres_wg_sat sort comment title 14-hour max wind gusts Saturday
The plots below shows the error in MSLP (shades), forecast (black contours) and analysis (green contours) for the forecast issued 8 Jan 12z. As reference, the NCEP forecast is also included, which for the Saturday storm was almost perfect (not the Friday one). The plots suggests that the ECMWF developed the cyclone somewhat too far north-east.
Gallery includeLabel fcerr_0812_ecmf sort comment title MSLP error 8 Jan 12z forecast ECMWF
Gallery includeLabel fcerr_0812_ncep sort comment title MSLP error 8 Jan 12z forecast NCEP
3.3 ENS
Cyclone feature 1km wind 600 km Friday 00z
...
Gallery includeLabel dal_600_fri sort comment title 1 km wind 600 km Friday
Cyclone feature 1km wind 600 km Saturday 12z
...
Gallery includeLabel dal_600_sat sort comment title 1 km wind 600 km Saturday
EFI Friday
The plots below show EFI and SOT for wind gusts valid 9 January.
...
CDF for Bergen, Norway valid 10 January (observed 37.7 m/s in town)
CDF for Lysekil, Sweden valid 10 January (observed 38 m/s, Private)
CDF for Vaxjo, Sweden valid 10 January (observed 29 m/s)
...
First plot: 8 January 06z - 9 January 06z. Second plot: 9 January 06z - 10 January 06z. Third plot: 10 January 06z - 11 January 06z.
Regime forecasts
...
Gallery includeLabel ws_9_prob25_dmi sort comment title Prob ws>25 m/s DMI-HIRLAM Friday
Gallery includeLabel ws_9_prob25_glameps sort comment title Prob ws>25 m/s GLAMEPS Friday
The plots below are the same as above but for 10 January.
...
Gallery includeLabel ws_10_prob25_dmi sort comment title Prob ws>25 m/s DMI Saturday
Gallery includeLabel ws_10_prob25_glameps sort comment title Prob ws>25 m/s GLAMEPS Saturday
4. Experience from general performance/other cases
...
- Early signal for transition to strong positive NAO
- Good predictability for the Friday storm over Scotland
- More problems for Saturday storms
6. Additional material
- Presentation from Fernando FD/RD March 2015 about the 10-metre wind difference in HRES and CF during Elon.
Obs/Fc scatter plot
The figure below shows the scatter plot of observations and short forecasts of 24-hour maximum wind gusts for 9 January (blue), 10 January (red) and 11 January (green). Tim found that there is a maximum in the SYNOP code (99 knot) for wind gusts, which seems to have been hit by 6 stations during this event.
