Status: Finalised Material from: Linus
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Discussed in the following Daily reports: |
1. Impact
On 9 November Stockholm, Sweden was hit by a severe blizzard. The city got around 40 cm of snow. The snow accumulation over 2 days was the largest since at least 1950 for Stockholm (all winter months included).
2. Description of the event
The plots below show the analyses of z500 and t850 for 6 November to 10 November.
The plots below shows 12-hour forecasts of MSLP and precipitation from the same period as the plots above.
The plots below shows the evolution of the snow depth in Sweden from 8 November 06z to 10 November 06z. The accumulation in Stockholm was almost 40 cm during this period.
The plot below shows an example of radar image during the snowfall (9 Nov 10z)
24-hour radar accumulations for 8 Nov 06z - 9 Nov 06z (left) and 9 Nov 06z - 10 Nov 06z (right), provided by Karin Jonsson, SHMI.
3. Predictability
3.1 Data assimilation
3.2 HRES
The plots below show the 24-hour precipitation from 8 November 18z to 9 November 18z for ECMWF HRES. The first plot shows the observations. Please note the observation of 37 mm over Stockholm, either indicating a very localised maximum or observation errors for that observations or the nearby ones (heavy snowfall is problematic for automatic stations). The model developed convection over the warm sea in all forecasts but missed the amplitude of the event over Stockholm.
3.3 ENS
The plots below show the evolution of the ensemble (blue) and HRES forecasts (red) for precipitation (left) and 2-metre temperature (right) for 8 November 00z to 10 November 00z. The cold anomaly was captured from 24 October, while the precipitation event was 'captured' from 5 October.
The plots below show the EFI and SOT for snowfall on 8 November. The right panels show the values of the 99th percentile of the model climate.
The plots below shows the EFI and SOT for snowfall on 9 November.
3.4 Monthly forecasts
The plots below show the MSL anomalies for 7-13 November.
The plots below show the 2-metre temperature anomalies for 7-13 November.
3.5 Comparison with other centres
The plots below show the 24-hour precipitation from control forecast of DMI limited area ensemble.
Comparison of limited area models from SMHI and ECMWF for 12-hour precipitation (provided by Karin Jonsson, SMHI).
4. Experience from general performance/other cases
5. Good and bad aspects of the forecasts for the event
- Early detection of cold anomaly for the period
- The model captured the development of convection over the Baltic Sea
- The model missed the amplitude of the event over Stockholm
6. Additional material
Status:Ongoing analysis Material from: Linus
| Show If | ||
|---|---|---|
| ||
Discussed in the following Daily reports: |
1. Impact
On 9 November Stockholm, Sweden was hit by a severe blizzard. The city got around 40 cm of snow. The snow accumulation over 2 days was the largest since at least 1950 for Stockholm (all winter months included).
2. Description of the event
The plots below show the analyses of z500 and t850 for 6 November to 10 November.
...
24-hour radar accumulations for 8 Nov 06z - 9 Nov 06z (left) and 9 Nov 06z - 10 Nov 06z (right), provided by Karin Jonsson, SHMI.
3. Predictability
3.1 Data assimilation
3.2 HRES
The plots below show the 24-hour precipitation from 8 November 18z to 9 November 18z for ECMWF HRES. The first plot shows the observations. Please note the observation of 37 mm over Stockholm, either indicating a very localised maximum or observation errors for that observations or the nearby ones (heavy snowfall is problematic for automatic stations). The model developed convection over the warm sea in all forecasts but missed the amplitude of the event over Stockholm.
3.3 ENS
The plots below show the evolution of the ensemble (blue) and HRES forecasts (red) for precipitation (left) and 2-metre temperature (right) for 8 November 00z to 10 November 00z. The cold anomaly was captured from 24 October, while the precipitation event was 'captured' from 5 October.
...
The plots below shows the EFI and SOT for snowfall on 9 November.
3.4 Monthly forecasts
The plots below show the MSL anomalies for 7-13 November.
...
The plots below show the 2-metre temperature anomalies for 7-13 November.
3.5 Comparison with other centres
The plots below show the 24-hour precipitation from control forecast of DMI limited area ensemble.
...
Comparison of limited area models from SMHI and ECMWF for 12-hour precipitation (provided by Karin Jonsson, SMHI).
4. Experience from general performance/other cases
...
5. Good and bad aspects of the forecasts for the event
- Early detection of cold anomaly for the period
- The model captured the development of convection over the Baltic Sea
- The model missed the amplitude of the event over Stockholm