Status:Ongoing analysis Material from: Linus, Esti, Ivan
Picture
1. Impact
On 10 august the summer storm Johanne hit south-western Scandinavia with strong winds and rainfall. However, earlier forecasts predicted the storm to hit the Netherlands.
2. Description of the event
The series of plots below show analysis of MSLP and 6-hour precipitation (top) and Z500 and T850 (bottom) from 9 Aug 00z to 10 Aug 12z.
The plot below shows the maximum wind gusts in the Netherlands on 9 August.
3. Predictability
3.1 Data assimilation
The plot below show the increment for the analysis 9 August 12UTC, which decreased the magnitude of the cyclone.
3.2 HRES
The plot below show observed 24-hour wind gusts (first plot) valid for 10 August and HRES forecasts for 24-hour maximum wind gusts (shade) and MSLP valid 10 August 12UTC (contour). The forecast from 8 August 12UTC gave much strong winds, and the next set of plots focus on 9 August.
The plot below show observed 24-hour wind gusts (first plot) valid for 9 August 12UTC to 10 August 12UTC and HRES forecasts for 24-hour maximum wind gusts (shade) and MSLP valid 10 August 00UTC (contour).
3.3 ENS
The plots below shows EFI and SOT for wind gusts valid 10 August.
The plots below show cyclone feature maps for 1 km maximum wind within 300 km radius, valid for 10 August 12UTC.
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
- False alarm for the windstorm to hit the Netherlands.
- Big jump in signal from 6 to 7 August