## 3 Results and Discussion
### Strong-Wind Events
The synoptic situation during the Ylva storm event can be described by a strong low-pressure system (970 mbar) located in the Norwegian sea and a high-pressure system (1025 mbar) over the Kola peninsula to the east of North Norway [41]. The counterclockwise wind around the low-pressure system created strong wind from the southeast as the system moved north along the Norwegian coast. Figure 8: Measured and modelled wind speeds during Ylva storm. RMSE for this event is shown in legend for each model. Figure 10 shows the wind speed of 80 magl in D04 in two instances during the Ylva event, on 23 November at 00:00 and 20.20, respectively. The first instance is at the start of the event (Figure 10a), when the wind speed builds up at Fakken as the low-pressure systems come closer. The two large fjords south of Fakken are separated by the Lyngen Alps that direct the wind north on its eastern side, which then turns more easterly and against Fakken as it passes this mountain range. The next instance is in the middle of the storm (Figure 10b), when the measurements show the highest wind speeds. The overall wind direction has now turned slightly anticlockwise, but the fjords and mountains around Fakken make the wind direction at the measurement mast location very similar. The Lyngen Alps still lead some wind east of the mountain range in a northerly direction along the fjord, and a high-wind-speed location can be seen at the ocean in front of the Fakken wind park location. The complex terrain creates localised shadowing and tunnelling effects, and lee-side amplification indicates mountain waves in several places in the region, as also discussed in [27]. The wind speeds around Fakken for WRF D04 and WRF LES are shown in Figure 11, in the upper and lower rows, respectively. The upper left plot shows wind using WRF D04 on 23 November at 00:00, the same as in Figure 10a, but now zoomed in at Fakken wind park. The D04 results show a smooth wind field around Fakken wind park, with some blocking of wind in front of the mountain to the left of the wind park. The LES model, in the lower left plot, has higher wind speeds near the red circle that marks the location of the measurement mast, as well as reduced wind speeds in front of the low hill where the turbines are mounted. Closer to the mountains, the steeper terrain in the LES model also creates stronger shadowing effects, and we find indications of a mixed wind situation behind the mountain east of the mast. Turning to the right-hand plots, on 23 November at 20:20 in the middle of the storm, note that the wind speed colour range is now 0-52 m/s. The differences between D04 and LES are similar to those earlier in time. The terrain effects  
Figure 9: Surface-level pressure in WRF D01 23 November at 20:20 shown as red dashed contour lines. Wind barbs from lowest model level. of blocking are much clearer in LESs compared to D04, and the speed increase along the low hills inside the Fakken wind park is clearly visible. The strong wind speed-up effects behind the eastern mountain are more distinct at this time, indicating lee wind behind this mountain. Figure 11: Wind at 80 magl from WRF D04 (**upper** row) and WRF LES (**lower** row). Red circle: Location of measurement mast. Left plots: 23 November at 00:00; right plots: 23 November at 20:20. Contour lines every 100 m, starting at 50 masl. Figure 10: Wind speed and wind barbs at 80 magl from WRF D04. Red dot: Location of measurement mast. Colour: Wind speed; note different scales. Contour lines every 200 m, starting at sea level.