Status: Finalised Material from: Ivan, Esti, Linus
1. Impact
On 19 December an event of freezing rain affected northern Sweden, and caused power outages and some traffic difficulties. It was the first time SMHI put out an amber warning for freezing rain. At the same time there was some observation in Germany.
2. Description of the event
The plot below shows the situation on 15z on 19 December, with MSLP (contour), T925 (shade) and precipitation type (also shaded). The freezing rain (red) appear in the warm air advection over northern Sweden.
3. Predictability
3.1 Data assimilation
3.2 HRES
3.3 ENS
Plot figure below includes plot showing the probability of the most likely precipitation type from 4 forecasts compared to observations for 18 UTC on 19 Dec. The event in northern Sweden was well captured, while the event in Germany was missed.
The plots below show the metgram product for precipitation type (probabilities of each category of precipitation with different intensities) for Vidsel (65.9N, 20.2E) in northern Sweden. The event was well captured at least 3-4 days in advance with some signal also present 6-7 days in advance.
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
- Good predictability of the event in northern Sweden in the medium-range