Status:Finalised Material from: Linus
Discussed in the following Daily reports:
Picture
1. Impact
On the 14 March strong wind and precipitation hit northern Scandinavia together wind precipitation. The station Stora Sjofallet in Sweden measured 36 m/s in mean wind and 47 m/s in the gusts (purple and black in the plots). After the storm, a ski resort in the area had a major avalanche, probably an effect of the snowfall and wind.
2. Description of the event
The figures above show the 24-hour maximum wind speed (left) and wind gusts (right) for the 14 February. Along the Norwegian coast several stations had gusts more than 35 m/s. The Stora Sjofallet station is the purple and black dots respectively in the figures. The station is on the eastern end of a lake. On the western side the station Ritsem is located, with much lower wind speeds.
3. Predictability
3.1 Data assimilation
3.2 HRES
Gallery includeLabel hres_wg title HRES 24-hour wind gusts and MSLP
| includeLabel | hres_wg |
|---|---|
| title | HRES 24-hour wind gusts and MSLP |
The figures above show example of wind gusts forecast for 1, 2 and 3 days before the event. Also the three day forecast was good for the event.
...
The figures above show the orography from T1279 (HRES, left) and T3999 (right). In the left plot the observation stations are plotted where Ritsem is in the western end and Stora Sjofallet on the eastern end of the narrow lake (although I think Stora Sjofallet should be somewhat more left than plotted). Here we see that the lake is not properly resolved in the orography for T1279, while it looks better in T3999. My experience is that 5 km is not enough resolution for this gap, one rather need 1 km or 500m.
3.3 ENS
The CDF is for wind speed (left) and wind gusts (right) for Stora Sjofallet, valid on the 14 March. Here we see that the wind was extreme for the area.
3.4 Monthly forecasts
3.5 Comparison with other centres
4. Experience from general performance/other cases
5. Good and bad aspects of the forecasts for the event
- The synoptic forcing of the event was well forecast 2-3 days before the event.
- For Stora Sjofallet, the mean wind was far too low but the wind gusts were ok
- For Ritsem, the mean wind was not very strong, as in the forecast, but the wind gusts were too high.
- Is this an effect of sub-grid variability or a more general mountain problem?
- Is the gust/mean wind ratio realistic for this case?